
Niacinamide, also known as nicotinamide, is a water-soluble form of vitamin B3 (molecular formula: C₆H₆N₂O) that has become a popular skincare ingredient due to its versatility and proven efficacy. Numerous clinical studies support its beneficial effects, contributing to its rise in popularity in the past few years.

It is interesting to note that despite the numerous documented benefits, niacinamide is officially listed only under the function "smoothing" in the EU's CosIng database. This limited categorization reflects regulatory classification rather than the comprehensive scientific evidence available.

### Benefits of Niacinamide in Skincare

**1. Anti-inflammatory and Acne Management**  
Niacinamide exhibits significant anti-inflammatory properties, which help reduce redness and irritation associated with acne and rosacea. Studies have shown that topical niacinamide can effectively decrease inflammatory lesions and sebum production, making it an excellent choice for acne-prone skin (1)(5)(8). One clinical trial even found it to be as effective as clindamycin in treating inflammatory acne (8).

**2. Improving Skin Barrier Function**  
A healthy skin barrier prevents moisture loss and shields against irritants. Niacinamide enhances barrier function by stimulating the synthesis of ceramides and fatty acids, thus helping to reduce transepidermal water loss (TEWL) and improving skin hydration (2).

**3. Reduction of Hyperpigmentation**  
Niacinamide can effectively lighten dark spots and hyperpigmentation by inhibiting melanosome transfer from melanocytes to keratinocytes. Clinical trials demonstrated significant improvements in hyperpigmentation after consistent topical application of niacinamide (3),(4),(7). In one study, niacinamide 4% showed comparable efficacy to hydroquinone 4% in treating melasma, with fewer side effects (7).

**4. Anti-aging Effects**  
Niacinamide contributes to anti-aging by enhancing collagen production, reducing fine lines and wrinkles, and improving skin elasticity. One double-blind clinical trial found visible improvements in wrinkle reduction and skin elasticity after 12 weeks of niacinamide treatment (4).

**5. Sebum Regulation**  
In addition to reducing inflammation, niacinamide regulates sebum production, beneficial for managing oily skin. A study demonstrated that applying 2% niacinamide significantly reduced sebum excretion rates after two weeks (1).

### Optimal Concentrations and Usage

The optimal concentration of niacinamide for skincare ranges between 2% and 5%, with higher concentrations generally well-tolerated but occasionally causing mild irritation in sensitive skin. Daily use is safe and often recommended for ongoing skin improvement (6).

### Potential Side Effects

Niacinamide is generally well-tolerated; however, in rare cases, high concentrations may cause redness or irritation. To minimize potential side effects, it is advisable to begin with lower concentrations and gradually increase if needed (6).

### Conclusion

Niacinamide is a scientifically supported skincare ingredient offering multiple dermatological benefits, including anti-inflammatory, skin barrier enhancement, hyperpigmentation reduction, anti-aging effects, and sebum regulation. Its proven **safety profile and broad-spectrum efficacy** make it an excellent choice for inclusion in skincare routines targeting diverse skin concerns.

### References

1. **Draelos, Z. D., Matsubara, A., & Smiles, K. (2006).** The effect of 2% niacinamide on facial sebum production. *Journal of Cosmetic and Laser Therapy, 8*(2), 96-101. [The effect of 2% niacinamide on facial sebum production: Journal of Cosmetic and Laser Therapy: Vol 8 , No 2 - Get Access](https://doi.org/10.1080/14764170600717704)
  
2. **Tanno, O., Ota, Y., Kitamura, N., Katsube, T., & Inoue, S. (2000).** Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier. *British Journal of Dermatology, 143*(3), 524-531. [https://academic.oup.com/bjd/article-abstract/143/3/524/6691624?redirectedFrom=fulltext](https://academic.oup.com/bjd/article-abstract/143/3/524/6691624?redirectedFrom=fulltext)
  
3. **Hakozaki, T., Minwalla, L., Zhuang, J., et al. (2002).** The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. *British Journal of Dermatology, 147*(1), 20-31. [https://doi.org/10.1046/j.1365-2133.2002.04834.x](https://doi.org/10.1046/j.1365-2133.2002.04834.x)
  
4. **Bissett, D. L., Miyamoto, K., Sun, P., Li, J., & Berge, C. A. (2004).** Topical niacinamide reduces yellowing, wrinkling, red blotchiness, and hyperpigmented spots in aging facial skin. *International Journal of Cosmetic Science, 26*(5), 231-238. [Topical niacinamide reduces yellowing, wrinkling, red blotchiness, and hyperpigmented spots in aging facial skin - PubMed](https://pubmed.ncbi.nlm.nih.gov/18492135/)
  
5. **Walocko, F. M., et al. (2017).** The role of nicotinamide in acne treatment. *Dermatologic Therapy, 30*(5), e12481. [The role of nicotinamide in acne treatment - Walocko - 2017 - Dermatologic Therapy - Wiley Online Library](https://doi.org/10.1111/dth.12481)
  
6. **Rolfe, H. M. (2014).** A review of nicotinamide: treatment of skin diseases and potential side effects. *Journal of Cosmetic Dermatology, 13*(4), 324–328.  [https://pubmed.ncbi.nlm.nih.gov/25399625](https://pubmed.ncbi.nlm.nih.gov/25399625)
  
7. **Navarrete-Solís, J., et al. (2011).** A double-blind, randomized clinical trial of niacinamide 4% versus hydroquinone 4% in the treatment of melasma. *Dermatology Research and Practice, 2011*, 379173. [A Double‐Blind, Randomized Clinical Trial of Niacinamide 4% versus Hydroquinone 4% in the Treatment of Melasma - Navarrete-Solís - 2011 - Dermatology Research and Practice - Wiley Online Library](https://doi.org/10.1155/2011/379173)
  
8. **Shalita, A. R., et al. (1995).** Topical nicotinamide compared with clindamycin gel in the treatment of inflammatory acne vulgaris. *International Journal of Dermatology, 34*(6), 434-437. [TOPICAL NICOTINAMIDE COMPARED WITH CLINDAMYCIN GEL IN THE TREATMENT OF INELAMMATORY ACNE VULGARIS - SHALITA - 1995 - International Journal of Dermatology - Wiley Online Library](https://doi.org/10.1111/j.1365-4362.1995.tb04449.x)  


A versatile, well-tolerated ingredient with proven benefits for acne, pigmentation, skin barrier repair, and aging.

Niacinamide


Farnesol (C₁₅H₂₆O) is a naturally occurring substance found in essential oils such as rose, jasmine, and neroli. In cosmetics, it is primarily used as a fragrance compound and is listed in the EU’s CosIng database under “**deodorant**” and “**perfuming**” functions. Beyond its aromatic appeal, farnesol exhibits bioactive properties—most notably antimicrobial effects—which have drawn interest for dermatological applications.

## Antimicrobial and Antifungal Properties

Farnesol has been shown to inhibit the growth of several **human skin pathogens**, especially those associated with biofilm formation and chronic infections. A 2023 study demonstrated that a farnesol emulsion was effective against biofilms of *Klebsiella pneumoniae*, *Enterococcus faecium*, and *Enterobacter cloacae* on ex vivo human skin, suggesting a **potential role in topical antimicrobial formulations**. These effects, however, have only been tested in controlled laboratory environments and not in clinical skincare products [1]. Another 2024 publication explored farnesol's use against *Acinetobacter baumannii*, a multidrug-resistant skin pathogen, showing that it significantly impaired biofilm development and microbial viability [2].

Farnesol also shows potent antifungal effects, particularly against *Candida albicans* [3]. While not yet used in commercial antifungal skin treatments, these findings support further development.

## Allergenicity and Safety Concerns

Despite its benefits, farnesol is a **well-documented contact allergen**. It is one of the 26 fragrance allergens that must be declared on cosmetic labels in the European Union. Its structure allows it to bind to skin proteins, leading to sensitization in some individuals. Repeated exposure may result in **allergic contact dermatitis**, particularly in those with existing skin conditions or sensitivities [4].

In a dermatological risk assessment framework, farnesol is categorized as a **moderate to strong sensitizer**. Therefore, its inclusion in skincare products—especially leave-on formulations—should be limited to **low concentrations**, and preferably used in rinse-off products or paired with allergen mitigation strategies.

## References

1. **Tan, L., Ma, R., Katz, A. J., & Levi, N. (2024).** Farnesol emulsion as an effective broad-spectrum agent against ESKAPE biofilms. *Antibiotics, 13*(8), 778.  
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11352207](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11352207)
  
2. **Tan, L., Ma, R., Katz, A. J., & Levi, N. (2024).** Farnesol repurposing for prevention and treatment of *Acinetobacter baumannii* biofilms. *Biofilm, 7*, 100198.  
[https://pubmed.ncbi.nlm.nih.gov/38706984](https://pubmed.ncbi.nlm.nih.gov/38706984)
  
3. **Shen, T., Tian, B., Liu, W., Yang, X., Sheng, Q., Li, M., Wang, H., Wang, X., Zhou, H., Han, Y., Ding, C., & Sai, S. (2024).** Transdermal administration of farnesol-ethosomes enhances the treatment of cutaneous candidiasis induced by *Candida albicans* in mice. *Microbiology Spectrum, 12*(4), e0424723.  
  [https://pubmed.ncbi.nlm.nih.gov/38415658](https://pubmed.ncbi.nlm.nih.gov/38415658)
  
4. **Farnesol – An Overview.** *ScienceDirect Topics.* [https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/farnesol](https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/farnesol)  


A substance that offers antimicrobial benefits but poses a risk of skin sensitization

Farnesol


**Linalool** (C₁₀H₁₈O) is a naturally occurring **monoterpene alcohol** found in essential oils such as lavender, coriander, basil, and thyme. In cosmetics, it is primarily used as a **fragrance ingredient**, prized for its floral, slightly citrusy scent. While linalool is widespread in personal care products, its biological activity and safety profile warrant closer scrutiny.

## Antimicrobial Activity

Linalool has demonstrated **antimicrobial properties**, particularly against Gram-negative bacteria such as *Pseudomonas fluorescens*. Its mechanism of action appears to involve the disruption of bacterial membranes and interference with key metabolic processes. These findings suggest that linalool may contribute to the microbial stability of cosmetic formulations [1].

## Safety and Sensitization Concerns

Despite being commonly used, linalool poses **safety concerns** related to **oxidation**. When exposed to air, linalool can oxidize and form **hydroperoxides**, which are recognized as **potent skin sensitizers**. These oxidation products, rather than linalool itself, are responsible for most allergic reactions associated with linalool exposure [2].

In clinical settings, linalool is one of the 26 fragrance allergens that must be labeled on cosmetic packaging in the European Union. Sensitization typically occurs with repeated exposure, especially in leave-on products or when formulations are poorly stabilized.

## Conclusion

Linalool is a widely used fragrance compound with **some antimicrobial potential**, but its **oxidation byproducts are well-established allergens**. Formulas should ensure antioxidant protection or encapsulation strategies to reduce oxidation, and consumers with sensitive skin may benefit from avoiding products containing linalool.

## References

1. **Guo, F., Chen, Q., Liang, Q., Zhang, M., Chen, W., Chen, H., Yun, Y., Zhong, Q., & Chen, W. (2021).** Antimicrobial activity and proposed action mechanism of linalool against *Pseudomonas fluorescens*. *Frontiers in Microbiology, 12*, 562094.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875898](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875898)
  
2. **Kuresepi, S., Vileno, B., Lepoittevin, J.-P., & Giménez-Arnau, E. (2020).** Mechanistic insights on skin sensitization to linalool hydroperoxides: EPR evidence on radical intermediates formation in reconstructed human epidermis and 13C NMR reactivity studies with thiol residues. *Chemical Research in Toxicology, 33*(7), 1922–1932.  
  [https://pubmed.ncbi.nlm.nih.gov/32441093](https://pubmed.ncbi.nlm.nih.gov/32441093)  


A fragrance compound with mild antimicrobial effects, but its oxidized forms are known skin sensitizers.

Linalool


**Squalane**, a hydrogenated derivative of squalene, is a skincare ingredient known for its emollient properties, chemical stability, and compatibility with various skin types [1]. It is primarily derived from plant sources such as olives [1] and can also be produced biotechnologically from sugarcane through microbial fermentation [5]. Its precursor, squalene, is naturally present in human skin sebum, making squalane structurally similar to natural skin lipids [4].

## Skincare Benefits

### Moisturization and Skin Barrier Enhancement

Squalane functions effectively as a moisturizer due to its emollient characteristics. Its lightweight texture allows it to be suitable for oily and acne-prone skin types, improving skin elasticity and brightness with consistent use [2].

### Enhanced Penetration of Active Ingredient

Squalane-based emulsions have been shown to increase the skin penetration of polyphenolic compounds, indicating its ability to enhance the delivery of certain active ingredients in skincare formulations [3].

### Antioxidant Properties

Squalane has demonstrated antioxidant properties, which may contribute to protecting the skin from environmental stressors [4].

## Safety Profile and Stability

Squalane has a documented safety profile, confirmed as non-irritating, non-sensitizing, and safe for topical cosmetic use [1]. Its saturated chemical structure provides resistance to oxidation, making squalane stable for inclusion in skincare products [1].

Squalane is preferred over squalene in skincare formulations due to its superior chemical stability. Squalene contains unsaturated double bonds, making it prone to oxidation, which can cause skin irritation and shorten product shelf life. In contrast, squalane's fully saturated chemical structure significantly reduces oxidation, resulting in greater stability, safety, and suitability for long-term cosmetic use [1].

## Conclusion

Scientific evidence supports squalane as a skincare ingredient with moisturizing properties, the ability to enhance ingredient penetration, stability in formulations, and a reliable safety profile. Its antioxidant activity further underscores its potential usefulness in skincare formulations. Additionally, its structural similarity to naturally occurring skin sebum supports its compatibility with the skin.

## References

1. **Cosmetic Ingredient Review Expert Panel. (2010).** Final report on the safety assessment of squalane and squalene. *International Journal of Toxicology, 29*(3_suppl), 94S–115S.  
[https://journals.sagepub.com/doi/pdf/10.3109/10915818209013146](https://journals.sagepub.com/doi/pdf/10.3109/10915818209013146)
  
2. **Rastogi, R., & Gholap, A. (2023).** Daily use of a bakuchiol and squalane-containing face serum impacts skin esthetics. *CosmoDerma, 3*, 182.  
[https://cosmoderma.org/daily-use-of-a-bakuchiol-and-squalane-containing-face-serum-impacts-skin-esthetics/](https://cosmoderma.org/daily-use-of-a-bakuchiol-and-squalane-containing-face-serum-impacts-skin-esthetics/).
  
3. **Oliveira, A. L. S., Valente, D., Moreira, H. R., Pintado, M., & Costa, P. (2022).** Effect of squalane-based emulsion on polyphenols skin penetration: Ex vivo skin study. *Colloids and Surfaces B: Biointerfaces, 218*, 112779.  
[https://pubmed.ncbi.nlm.nih.gov/35994992](https://pubmed.ncbi.nlm.nih.gov/35994992)
  
4. **Kim, S.-K., & Karadeniz, F. (2012).** Biological importance and applications of squalene and squalane. *Advances in Food and Nutrition Research, 65*, 223–233.  
  [https://pubmed.ncbi.nlm.nih.gov/22361190/](https://pubmed.ncbi.nlm.nih.gov/22361190/)
  
5. **Paramasivan, K., & Mutturi, S. (2022).** Recent advances in the microbial production of squalene. *World Journal of Microbiology and Biotechnology, 38*(5), 91.  
  [https://pubmed.ncbi.nlm.nih.gov/35426523/](https://pubmed.ncbi.nlm.nih.gov/35426523/)
  

A stable, skin-identical emollient that supports moisturization, enhances active delivery, and is well-tolerated by all skin types.

Squalane


**Glycerin** (also known as **glycerol**) is a naturally occurring **trihydroxy alcohol** (C₃H₈O₃) derived from plant oils or animal fats. Clear, odorless, and viscous, glycerin is widely used in skincare for its powerful moisturizing effects. Its primary cosmetic function is as a **humectant**, meaning it draws water into the outermost layer of the skin to support hydration and barrier function.

## Skin Benefits

### Hydration and Moisture Retention

Glycerin is one of the most effective humectants available in skincare. It binds water from the environment and deeper skin layers to the stratum corneum, improving skin hydration, softness, and plumpness. A 2016 review identified glycerin as outperforming other common humectants like urea and hyaluronic acid in terms of efficacy [1].

### Enhancement of Skin Barrier Function

By maintaining optimal moisture levels in the outer skin layer, glycerin supports the integrity of the skin barrier. This reduces transepidermal water loss (TEWL) and improves resistance to irritants and environmental stressors [2].

### Wound Healing and Protective Effects

Glycerin has been shown to contribute to skin healing and soothe irritations. Its hydrating and barrier-protecting properties make it beneficial for individuals with dry, sensitive, or inflamed skin, including those with eczema or psoriasis [1] [2].

## Safety Profile

Glycerin has an excellent safety profile and is considered non-toxic, non-comedogenic, and non-irritating. It is well tolerated across all skin types, including sensitive and acne-prone skin. It is one of the most universally accepted and skin-compatible ingredients used in cosmetics.

## References

1. **Sethi, A., Kaur, T., Malhotra, S. K., & Gambhir, M. L. (2016)**. Moisturizers: The Slippery Road. *Indian Journal of Dermatology, 61*(3), 279–287. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4885180/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4885180/)
  
2. **Fluhr, J. W., Darlenski, R., & Surber, C. (2008).** Glycerol and the skin: holistic approach to its origin and functions. *British Journal of Dermatology, 159*(1), 23–34.  
[https://pubmed.ncbi.nlm.nih.gov/18510666](https://pubmed.ncbi.nlm.nih.gov/18510666)
  

A powerful, skin-compatible humectant that hydrates, protects the barrier, and suits even the most sensitive skin.

Glycerin


Salicylic acid is a [beta-hydroxy acid (BHA)](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/bha-beta-hydroxy-acid-) used in dermatology to treat various skin conditions, most notably acne vulgaris.

## Mechanism of Action

Salicylic acid works by loosening the bonds between skin cells in the outermost layer of the skin. This helps dead cells shed more easily and prevents them from building up and clogging pores — one of the main causes of acne [1].

## Skincare Benefits

### Efficacy in Acne Treatment

Multiple clinical studies support the use of salicylic acid for acne. A placebo-controlled trial using a 2% salicylic acid cleanser over 8 weeks reported statistically significant reductions in both inflammatory and non-inflammatory lesions [2]. Comparative trials have also shown its effectiveness is on par with other superficial chemical peels, including glycolic acid and [Jessner’s solution](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/jessner-s-solution) [3].

### Exfoliation and Skin Renewal

In addition to acne treatment, salicylic acid enhances epidermal turnover and smooths skin texture. It has been used to treat melasma, freckles and other forms of photodamage by accelerating cell renewal and removing superficial pigment [1, 4].

### Anti-Inflammatory Properties

Salicylic acid exhibits anti-inflammatory activity, the concentration at which the anti-inflammatory action is most pronounced being between 0.5% and 5%. This makes it beneficial for inflamed acne lesions [1].

## Safety and Considerations

Salicylic acid is generally well-tolerated at concentrations of 0.5% to 2% in over-the-counter skincare. Potential side effects include mild irritation, dryness, or skin peeling, especially in individuals with sensitive skin [1].

Although exfoliating agents like alpha-hydroxy acids are known to increase sensitivity to ultraviolet radiation, available evidence suggests that salicylic acid may not share this effect [5]. Nonetheless, the use of daily sun protection is still advisable during salicylic acid treatment.

## Conclusion

Salicylic acid is a well-studied and effective topical agent for the treatment of acne and superficial skin disorders. Its ability to exfoliate within pores, reduce inflammation, and promote epidermal turnover makes it a valuable and evidence-based component in many dermatological and cosmetic formulations.

## References

1. **Arif, T. (2015).** Salicylic acid as a peeling agent: a comprehensive review. *Clinical, Cosmetic and Investigational Dermatology, 8*, 455–461.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4554394/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4554394/)
  
2. **Woodruff, J., & Appa, Y. (2013).** A double-blind, placebo-controlled evaluation of a 2% salicylic acid cleanser for improvement of acne vulgaris. *Journal of the American Academy of Dermatology, 68*(4), AB12.  
  [https://www.jaad.org/article/S0190-9622(12)01331-X/fulltext](https://www.jaad.org/article/S0190-9622(12)01331-X/fulltext)]
  
3. **Bae, B. G., et al. (2013).** Salicylic acid peels versus Jessner's solution for acne vulgaris: a comparative study. *Dermatologic Surgery, 39*(2), 248–253.  
  [https://pubmed.ncbi.nlm.nih.gov/23121256/](https://pubmed.ncbi.nlm.nih.gov/23121256/)
  
4. **Kligman, D. E., & Kligman, A. M. (1998).** Salicylic acid peels for the treatment of photoaging. *Dermatologic Surgery, 24*(3), 325–328.  
  [https://pubmed.ncbi.nlm.nih.gov/9537006/](https://pubmed.ncbi.nlm.nih.gov/9537006/)
  
5. **Kornhauser, A., Wei, R. R., Yamaguchi, Y., Coelho, S. G., Kaidbey, K., Barton, C., Takahashi, K., Beer, J. Z., Miller, S. A., & Hearing, V. J. (2009).** The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin. *Journal of Dermatological Science, 55*(1), 10–17.  
[https://pubmed.ncbi.nlm.nih.gov/19411163](https://pubmed.ncbi.nlm.nih.gov/19411163)
  

A pore-clearing exfoliant with and acne-fighting benefits.

Salicylic Acid


Caffeine (1,3,7-trimethylxanthine) is a naturally occurring alkaloid found in coffee, tea, and cocoa. In skincare, it is used for its potential vasoconstrictive, antioxidant, and lipolytic properties. It is commonly included in formulations targeting under-eye puffiness, dark circles, and cellulite.

## Clinical Evidence of the Effects on Under-Eye Puffiness

A randomized, double-blind, placebo-controlled study evaluated the efficacy of a 3% caffeine gel in reducing under-eye puffiness [1]. The study involved 34 volunteers who applied either the caffeine gel or a placebo gel. Both groups experienced reduced puffiness, but the **difference between them was not statistically significant.** However, 23.5% of participants responded better to the caffeine gel than to the placebo, suggesting individual variation. The authors concluded that the reduction in puffiness was more likely due to the cooling action of the gel base than to caffeine itself.

## Cellulite and Lipolysis

Caffeine is frequently used in topical products marketed for the appearance of cellulite. Mechanistically, it is thought to promote lipolysis (the breakdown of stored fat) by inhibiting phosphodiesterase (an enzyme that deactivates fat-burning signals), which increases intracellular levels of cyclic adenosine monophosphate, or cAMP (a chemical messenger that activates fat metabolism). Elevated cAMP levels can trigger the breakdown of triglycerides (fat molecules stored in cells). [2].

Clinical studies evaluating its effect on cellulite include:

- **Byun et al. (2015):** In a six-week open-label study, 15 women applied a cream containing 3.5% water-soluble caffeine and xanthenes to their thighs and upper arms twice daily. Statistically significant reductions in thigh (−0.7 cm) and upper-arm (−0.8 cm) circumference were reported, along with improved cellulite grading scores. The study lacked a control group and had a small sample size [3].
  
- **Dupont et al. (2014):** In a double-blind, randomized, placebo-controlled trial, 44 women applied a topical gel containing caffeine and multiple other actives twice daily for 84 days. Compared to the placebo group, the active gel significantly improved skin tonicity and reduced the orange-peel appearance and stubborn cellulite. Circumference measurements also decreased. No adverse events were reported. The contribution of caffeine alone could not be determined due to the presence of multiple actives [4].
  

The current evidence suggests that topical formulations containing caffeine may improve the appearance of cellulite in some users, but results depend on formulation, treatment duration, and the presence of additional ingredients. Studies specifically isolating caffeine’s contribution are limited.

## Antioxidant Activity

Caffeine has demonstrated antioxidant activity in both in vitro and in vivo models. It can scavenge reactive oxygen species (ROS) and reduce oxidative stress in skin cells exposed to ultraviolet radiation or pollution [5].

## Safety and Irritation

Topical caffeine is generally well tolerated. Mild irritation or dryness may occur, particularly in alcohol-based formulas or at high concentrations. No systemic effects have been reported in cosmetic use. In safety assessments, caffeine showed low irritation and sensitization potential [6].

## Conclusion

Caffeine has documented biological actions on the skin like lipolysis and antioxidant activity. Its effect on under-eye puffiness has been studied, but clinical evidence remains limited and results vary. Studies on cellulite reduction show small but measurable improvements in some individuals, though effects are formulation-dependent and often modest. Caffeine is generally safe for topical use and continues to be widely used in formulations targeting transient puffiness, localized fat, and oxidative stress.

## References

1. **Amnuaikit, T., Maneenuan, D., & Boonme, P. (2011).** Evaluation of caffeine gels on physicochemical characteristics and in vivo efficacy in reducing puffy eyes. *Journal of Applied Pharmaceutical Science, 1*(2), 56–59.  
  [https://www.japsonline.com/admin/php/uploads/20_pdf.pdf](https://www.japsonline.com/admin/php/uploads/20_pdf.pdf)
  
2. **Elias, M. L., Israeli, A. F., & Madan, R. (2023).** Caffeine in skincare: Its role in skin cancer, sun protection, and cosmetics. *Indian Journal of Dermatology, 68*(5), 546–550.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10718232/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10718232/)
  
3. **Byun, S.-Y., Kwon, S.-H., Heo, S.-H., Shim, J.-S., Du, M.-H., & Na, J.-I. (2015).** Efficacy of slimming cream containing 3.5% water-soluble caffeine and xanthenes for the treatment of cellulite: Clinical study and literature review. *Annals of Dermatology, 27*(3), 243–249.  
   [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4466275/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4466275/)
  
4. **Dupont, E., Journet, M., Oula, M.-L., Gomez, J., Léveillé, C., Loing, E., & Bilodeau, D. (2014).** An integral topical gel for cellulite reduction: Results from a double-blind, randomized, placebo-controlled evaluation of efficacy. *Clinical, Cosmetic and Investigational Dermatology, 7*, 73–88.  
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3933246](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3933246)
  
5. **Herman, A. (2013).** Caffeine's mechanisms of action and its cosmetic use. *Skin Pharmacology and Physiology, 26*(1), 8–14.  
   [https://pubmed.ncbi.nlm.nih.gov/23075568/](https://pubmed.ncbi.nlm.nih.gov/23075568/)
  
6. **Cherian, P. A., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., Liebler, D. C., Marks, J. G. Jr., Shank, R. C., Slaga, T. J., Snyder, P. W., Fiume, M., & Heldreth, B. (2024).** Safety Assessment of Methylxanthines as Used in Cosmetics. *International Journal of Toxicology, 43*(4_suppl), 42S–77S.  
  [https://journals.sagepub.com/doi/10.1177/10915818241260282](https://journals.sagepub.com/doi/10.1177/10915818241260282)
  

A circulation-boosting compound that may help reduce the appearance of cellulite and protects against oxidative stress.

Caffeine


Zinc oxide is a white, inorganic compound used extensively in topical skincare, most notably as a **broad-spectrum UV filter**. It is a mineral sunscreen agent that reflects and scatters both **UVA and UVB radiation**, protecting the skin from sunburn and long-term photodamage [1]. In addition to its sun-protective properties, it has recognized **anti-inflammatory** effects [2].

---

### UV Protection

Zinc oxide functions as a **physical (mineral) sunscreen**, forming a protective barrier on the skin’s surface that blocks and scatters UV rays. It provides **broad-spectrum protection**, covering both **UVB (290–320 nm)** and **UVA (320–400 nm)** wavelengths [1]. Unlike chemical filters, zinc oxide starts working immediately after application and is photostable — it does not degrade significantly upon sun exposure [3].

Micronized or nano-sized forms of zinc oxide are commonly used to reduce the white cast on skin without compromising UV protection. Studies have confirmed that these particles remain on the skin's surface and pose minimal risk of systemic absorption when used in cosmetic formulations [4].

### Anti-Inflammatory and Wound Healing Properties

Zinc oxide has been shown to reduce inflammation, making it useful in treating skin irritation, diaper rash, and acne lesions [5]. It promotes epithelialization and granulation tissue formation, supporting skin regeneration in wound care settings [6]. Some studies also suggest that zinc oxide has antimicrobial properties, helping reduce bacterial colonization in compromised skin [7].

### Safety Profile

Zinc oxide is considered **safe and well-tolerated**, even for sensitive skin. The Cosmetic Ingredient Review (CIR) and the U.S. FDA classify zinc oxide as safe for use in OTC sunscreen products at concentrations up to **25%** [8]. Studies show negligible systemic absorption, even when applied to damaged skin [4].

### Conclusion

Zinc oxide is a highly effective, broad-spectrum UV filter with additional benefits for inflamed or irritated skin. Its safety, photostability, and low risk of systemic exposure make it a reliable option in both daily sun protection and therapeutic skincare.

---

## References

1. **Beasley, D. G., & Meyer, T. A. (2010).** Characterization of the UVA protection provided by avobenzone, zinc oxide, and titanium dioxide in broad-spectrum sunscreen products. *American Journal of Clinical Dermatology, 11*(6), 413–421.  
  [https://pubmed.ncbi.nlm.nih.gov/20806994/](https://pubmed.ncbi.nlm.nih.gov/20806994/)
  
2. **Ågren, M. S., Phothong, N., Burian, E. A., Mogensen, M., Hædersdal, M., & Jorgensen, L. N. (2021).** Topical zinc oxide assessed in two human wound-healing models. *Acta Dermato-Venereologica, 101*, adv00400.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9367036/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9367036/)
  
3. **Mitchnick, M. A., Fairhurst, D., & Pinnell, S. R. (1999).** Microfine zinc oxide (Z-Cote) as a photostable UVA/UVB sunblock agent. *Journal of the American Academy of Dermatology, 40*(1), 85–90.  
  [https://doi.org/10.1016/S0190-9622(99)70532-3](https://doi.org/10.1016/S0190-9622(99)70532-3)
  
4. **Gulson, B., et al. (2010).** Small amounts of zinc from zinc oxide particles in sunscreens applied outdoors are absorbed through human skin. *Toxicological Sciences, 118*(1), 140–149.  
  [https://academic.oup.com/toxsci/article/118/1/140/1658967](https://academic.oup.com/toxsci/article/118/1/140/1658967)
  
5. **Gupta, M., Mahajan, V. K., Mehta, K. S., & Chauhan, P. S. (2014).** Zinc therapy in dermatology: a review. *Dermatology Research and Practice, 2014*, 709152.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4120804/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4120804/)
  
6. **Ågren, M. S. (1990).** Studies on zinc in wound healing. *Acta Dermato-Venereologica. Supplementum, 154*, 1–36.  
  [https://www.medicaljournals.se/acta/content/issue/70-154](https://www.medicaljournals.se/acta/content/issue/70-154)
  
7. **Reddy, K. M., et al. (2007).** Selective toxicity of zinc oxide nanoparticles to prokaryotic and eukaryotic systems. *Applied Physics Letters, 90*(213902).  
  [https://aip.scitation.org/doi/10.1063/1.2742324](https://aip.scitation.org/doi/10.1063/1.2742324)
  
8. **Kim, K.-B., Kim, Y. W., Lim, S. K., Roh, T. H., Bang, D. Y., et al. (2017).** Risk assessment of zinc oxide, a cosmetic ingredient used as a UV filter of sunscreens. *Journal of Toxicology and Environmental Health, Part B: Critical Reviews, 20*(3), 155–182.  
  [https://pubmed.ncbi.nlm.nih.gov/28509652/](https://pubmed.ncbi.nlm.nih.gov/28509652/)

A broad-spectrum mineral UV filter with additional skin-soothing and antimicrobial benefits.

Zinc Oxide


Tocopherol, commonly known as **vitamin E**, is a fat-soluble [antioxidant](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/antioxidant) widely used in dermatology and cosmetic formulations. Among its various forms, alpha-tocopherol is the most biologically active and is recognized for its ability to protect the skin from oxidative stress, support barrier function, and enhance moisturization [1].

## Skincare Benefits

### Antioxidant and Photoprotective Properties

Tocopherol acts as a potent antioxidant, neutralizing free radicals generated by environmental stressors such as ultraviolet (UV) radiation and pollution. This activity helps prevent lipid peroxidation in cell membranes, thereby protecting skin cells from oxidative damage [2]. When combined with vitamin C, tocopherol has been shown to provide synergistic photoprotection, reducing UV-induced [erythema](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/erythema) and DNA damage [3].

### Skin Barrier Support and Moisturization

Topical application of tocopherol has been demonstrated to improve skin hydration by enhancing the water-binding capacity of the [stratum corneum](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/stratum-corneum). This effect contributes to the maintenance of skin elasticity and smoothness [4]. Additionally, tocopherol supports the integrity of the skin barrier, reducing transepidermal water loss and improving overall skin resilience [1].

### Anti-Inflammatory Effects and Wound Healing

Tocopherol exhibits anti-inflammatory properties by inhibiting the release of pro-inflammatory cytokines and reducing oxidative stress in the skin. These effects can aid in the management of inflammatory skin conditions and support the wound healing process [2]. However, clinical evidence regarding its efficacy in scar reduction remains inconclusive [5], with some evidence that topical vitamin E may worsen the appearance of scars or cause contact dermatitis in certain individuals.

## Safety Profile

The Cosmetic Ingredient Review (CIR) Expert Panel has assessed tocopherol and its derivatives, concluding that they are safe for use in cosmetics at concentrations up to 5% [6]. While tocopherol is generally well-tolerated, rare cases of allergic contact dermatitis have been reported, particularly with tocopheryl acetate [7].

## Conclusion

Tocopherol is a well-established ingredient in skincare, offering antioxidant protection, barrier support, and moisturization. Its inclusion in topical formulations can enhance skin health and resilience.

## References

1. **Pinto, C. A. S. de O., Martins, T. E. A., Martinez, R. M., Freire, T. B., Velasco, M. V. R., & Baby, A. R. (2021).** Vitamin E in Human Skin: Functionality and Topical Products. *IntechOpen*.  
   [https://www.researchgate.net/publication/352470124_Vitamin_E_in_Human_Skin_Functionality_and_Topical_Products](https://www.researchgate.net/publication/352470124_Vitamin_E_in_Human_Skin_Functionality_and_Topical_Products)
  
2. **Keen, M. A., & Hassan, I. (2016).** Vitamin E in dermatology. *Indian Dermatology Online Journal, 7*(4), 311–315.  
   [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4976416/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4976416/)
  
3. **Lin, J. Y., Selim, M. A., Shea, C. R., Grichnik, J. M., Omar, M. M., Monteiro-Riviere, N. A., & Pinnell, S. R. (2003).** UV photoprotection by combination topical antioxidants vitamin C and vitamin E. *Journal of the American Academy of Dermatology, 48*(6), 866–874.  
  [https://www.jaad.org/article/S0190-9622(03)00781-3/fulltext](https://www.jaad.org/article/S0190-9622(03)00781-3/fulltext)
  
4. **Gehring, W., Fluhr, J., & Gloor, M. (1998).** Influence of vitamin E acetate on stratum corneum hydration. *Arzneimittelforschung, 48*(7), 772–775.  
  [https://pubmed.ncbi.nlm.nih.gov/9706379/](https://pubmed.ncbi.nlm.nih.gov/9706379/)
  
5. **Baumann, L., & Spencer, J.(1999).** The effects of topical vitamin E on the cosmetic appearance of scars. *Dermatologic Surgery, 25*(4), 311–315.  
  [https://journals.lww.com/dermatologicsurgery/Abstract/1999/04000/The_Effects_of_Topical_Vitamin_E_on_the_Cosmetic.13.aspx](https://journals.lww.com/dermatologicsurgery/Abstract/1999/04000/The_Effects_of_Topical_Vitamin_E_on_the_Cosmetic.13.aspx)
  
6. **Fiume, M. M., Bergfeld, W. F., Belsito, D. V., et al. (2018).** Safety Assessment of Tocopherols and Tocotrienols as Used in Cosmetics. *International Journal of Toxicology, 37*(2_suppl), 61S–94S.  
  [https://journals.sagepub.com/doi/pdf/10.1177/1091581818794455](https://journals.sagepub.com/doi/pdf/10.1177/1091581818794455)
  
7. **Kosari, P., Alikhan, A., Sockolov, M., & Feldman, S. R. (2010).** Vitamin E and allergic contact dermatitis. *Dermatitis, 21*(3), 148–153.  
  [https://pubmed.ncbi.nlm.nih.gov/20487657/](https://pubmed.ncbi.nlm.nih.gov/20487657/)
  

A skin-protecting antioxidant that supports the skin barrier and fights oxidative damage.

Tocopherol


Glycolic acid is the smallest alpha-hydroxy acid ([AHA](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/aha-alpha-hydroxy-acid-)) and is used in dermatology for its exfoliating properties and its ability to improve skin texture and tone. Its small molecular size allows it to penetrate the skin more effectively than other AHAs [1,2].

## Mechanism of Action

Glycolic acid reduces the cohesion between corneocytes in the outermost layer of the skin, promoting exfoliation and accelerating cell turnover [1]. This action results in smoother skin and improved radiance.

## Benefits

- **Acne Treatment:** Glycolic acid helps clear comedones and reduces inflammatory acne lesions through its exfoliating effect [2].
  
- **Hyperpigmentation Reduction:** It facilitates the removal of pigmented [keratinocytes](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/keratinocytes), aiding in the treatment of [melasma](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/melasma), post-inflammatory hyperpigmentation, and uneven skin tone [2].
  
- **Anti-Aging Effects:** Glycolic acid stimulates collagen production and improves skin elasticity, which can reduce the appearance of fine lines and wrinkles [3].
  

## Safety and Considerations

Glycolic acid is generally well-tolerated at concentrations up to 10% in over-the-counter skincare products. Side effects may include mild irritation, stinging, and [erythema](https://www.skinclasshub.com/theknowledgehub/cosmetic-glossary/erythema), especially in sensitive skin. It increases the skin’s sensitivity to ultraviolet radiation, so **daily sun protection** is recommended during use [4, 5].

## References

1. **Fartasch, M., Teal, J., & Menon, G. K. (1997).** Mode of action of glycolic acid on human stratum corneum: ultrastructural and functional evaluation of the epidermal barrier. *Archives of Dermatological Research, 289*(7), 404–409.  
  [https://pubmed.ncbi.nlm.nih.gov/9248619/](https://pubmed.ncbi.nlm.nih.gov/9248619/)
  
2. **Sharad, J. (2013).** Glycolic acid peel therapy – a current review. *Clinical, Cosmetic and Investigational Dermatology, 6*, 281–288.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3875240/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3875240/)
  
3. **Ditre, C. M., Griffin, T.D., Murphy, G. F., Sueki, H., Telegan, B., Johnson, W. C., Yu, R. J., & Van Scott, E. J. (1996).** Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study. *Journal of the American Academy of Dermatology, 34*(2 Pt 1), 187–195.  
[https://pubmed.ncbi.nlm.nih.gov/8642081](https://pubmed.ncbi.nlm.nih.gov/8642081)
  
4. **Andersen, F. A. (1998).** Final report on the safety assessment of glycolic acid, ammonium, calcium, potassium, and sodium glycolates, methyl, ethyl, propyl, and butyl glycolates. *International Journal of Toxicology, 17*(1_suppl), 1–241.  
  [https://journals.sagepub.com/doi/abs/10.1177/109158189801700101](https://journals.sagepub.com/doi/abs/10.1177/109158189801700101)
  
5. **Kornhauser, A., Wei, R. R., Yamaguchi, Y., Coelho, S. G., Kaidbey, K., Barton, C., Takahashi, K., Beer, J. Z., Miller, S. A., & Hearing, V. J. (2009).** The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage, and sunburn cell formation in human skin. *Journal of Dermatological Science, 55*(1), 10–17.  
  [https://pubmed.ncbi.nlm.nih.gov/19411163/](https://pubmed.ncbi.nlm.nih.gov/19411163/)
  

An effective exfoliant that enhances skin texture, diminishes hyperpigmentation, and reduces signs of aging.

Glycolic Acid


Avobenzone (INCI: Butyl Methoxydibenzoylmethane) is a synthetic oil-soluble sunscreen agent used in topical formulations to absorb **UVA radiation** (320–400 nm) [1]. It is currently one of the most widely used filters providing **broad-spectrum UVA protection**, essential for preventing long-term photodamage, photoaging, and skin cancer.

### Mechanism of Action

Avobenzone is a **dibenzoylmethane derivative** that absorbs UVA radiation by converting it into less harmful infrared radiation (heat). Its primary strength lies in its ability to absorb **long UVA1 wavelengths up to 400 nm**, which many other filters cannot efficiently block [2,3].

### Photostability and Formulation Concerns

Avobenzone is **photounstable**, meaning it degrades when exposed to sunlight. Within one hour of UV exposure, it can lose up to **36% of its protective ability** unless stabilized [4]. This instability can compromise sunscreen performance and lead to the generation of reactive oxygen species (ROS) [5], which are highly reactive molecules that can damage cellular components such as DNA, proteins, and lipids, contributing to oxidative stress and accelerating skin aging and inflammation.

To prevent degradation, avobenzone is often combined with photostabilizers such as:

- [**Octocrylene**](https://www.skinclasshub.com/theknowledgehub/ingredient-dictionary/octocrylene)
  
- [**Homosalate**](https://www.skinclasshub.com/theknowledgehub/ingredient-dictionary/homosalate)
  
- [**Tocopherol (Vitamin E)**](https://www.skinclasshub.com/theknowledgehub/ingredient-dictionary/tocopherol)
  
- **Diethylhexyl syringylidene malonate (Oxynex ST)** [6]
  

It is **incompatible with mineral filters** like zinc oxide and titanium dioxide in their untreated forms, as they can accelerate avobenzone breakdown unless encapsulated or coated [7].

### Safety and Regulatory Status

Avobenzone is generally well-tolerated and has **low skin penetration**. In vivo and in vitro studies show that it rarely causes irritation or sensitization in humans [8].

#### Regulatory Limits

- **United States (FDA):** Approved for use in sunscreens up to **3%** concentration [9]
  
- **European Union:** Approved up to **5%** [10]
  

### Conclusion

Avobenzone remains one of the most effective UVA filters available in cosmetic formulations. While it is photounstable on its own, formulations that include stabilizing agents can deliver broad-spectrum protection. Awareness of ingredient compatibility and regulatory limits is essential for effective and safe sunscreen formulation.

---

### References

1. **Beasley, D. G., & Meyer, T. A. (2010).** Characterization of the UVA protection provided by avobenzone, zinc oxide, and titanium dioxide in broad-spectrum sunscreen products. *American Journal of Clinical Dermatology, 11*(6), 413–421.  
  [https://pubmed.ncbi.nlm.nih.gov/20806994/](https://pubmed.ncbi.nlm.nih.gov/20806994/)
  
2. **Cowden, A. M., Whittock, A. L., Holt, E. L., Stavros, V. G., & Wills, M. (2023).** Synthesis and characterisation of novel composite sunscreens containing both avobenzone and octocrylene motifs. *RSC Advances, 13*(25), 17017–17027.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10245224/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10245224/)
  
3. **Sander, M., Burbidge, T., Sander, M., & Beecker, J. (2020).** The efficacy and safety of sunscreen use for the prevention of skin cancer. *CMAJ: Canadian Medical Association Journal, 192*(50), E1802–E1808.  
  [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7759112/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7759112/)
  
4. **Abdassah, M., Aryani, R., Surachman, E., & Muchtaridi, M. (2015).** In-vitro Assessment of Effectiveness and Photostability Avobenzone in Cream Formulations by Combination Ethyl Ascorbic Acid and Alpha Tocopherol Acetate. *Journal of Applied Pharmaceutical Science, 5*(06), 070–074.  
  [https://japsonline.com/admin/php/uploads/1532_pdf.pdf](https://japsonline.com/admin/php/uploads/1532_pdf.pdf)
  
5. **Silva, J. P. S., Afonso, S., Horita, K., Almeida, I. F., Amaral, M. H., Lobão, P. A., Costa, P. C., & Bahia, M. F. (2024).** Evaluation of the photoprotective and antioxidant potential of an avobenzone derivative. *Frontiers in Physiology, 15*, Article 1347414.  
  [https://www.frontiersin.org/articles/10.3389/fphys.2024.1347414/full](https://www.frontiersin.org/articles/10.3389/fphys.2024.1347414/full)
  
6. **Chaudhuri, R. K., Lascu, Z., Puccetti, G., Deshpande, A. A., & Paknikar, S. K. (2006).** Design of a photostabilizer having built-in antioxidant functionality and its utility in obtaining broad-spectrum sunscreen formulations. *Photochemistry and Photobiology, 82*(3), 823–828.  
  [https://doi.org/10.1562/2005-07-15-RA-612](https://doi.org/10.1562/2005-07-15-RA-612)
  
7. **Kockler, J., Oelgemöller, M., Robertson, S., & Glass, B. D. (2014).** Influence of titanium dioxide particle size on the photostability of the chemical UV-filters butyl methoxy dibenzoylmethane and octocrylene in a microemulsion. *Cosmetics, 1*(2), 128–139.  
  [https://www.mdpi.com/2079-9284/1/2/128](https://www.mdpi.com/2079-9284/1/2/128)
  
8. **U.S. Food and Drug Administration (FDA). (2021).** Sunscreen Drug Products for Over-the-Counter Human Use. Safety Data Submission on Avobenzone.  
  [https://downloads.regulations.gov/FDA-1978-N-0018-15718/attachment_1.pdf](https://downloads.regulations.gov/FDA-1978-N-0018-15718/attachment_1.pdf)
  
9. **U.S. Food & Drug Administration (FDA). (2021).** Final Administrative Order (OTC000006): Over-the-Counter Sunscreen Drug Products for Human Use.  
  [https://dps-admin.fda.gov/omuf/omuf/sites/omuf/files/primary-documents/2022-09/Final%20Administrative%20Order%20OTC000006_M020-Sunscreen%20Drug%20Products%20for%20OTC%20Human%20Use.pdf](https://dps-admin.fda.gov/omuf/omuf/sites/omuf/files/primary-documents/2022-09/Final%20Administrative%20Order%20OTC000006_M020-Sunscreen%20Drug%20Products%20for%20OTC%20Human%20Use.pdf)
  
10. **European Commission. (2024).** Annex VI – UV Filters Allowed in Cosmetic Products. Entry 15: Butyl Methoxydibenzoylmethane (Avobenzone) – Maximum concentration allowed: 5%. In *Cosmetic Products Regulation (EC) No 1223/2009*.  
  [https://ec.europa.eu/growth/tools-databases/cosing/reference/annexes/list/VI](https://ec.europa.eu/growth/tools-databases/cosing/reference/annexes/list/VI)

A chemical UVA filter that uniquely protects against long-range rays up to 400 nm.

Avobenzone


Octocrylene is a UV filter used in sunscreen formulations to absorb UVB and short UVA radiation, typically between 280–320 nm [1]. It is oil-soluble and contributes to product water-resistance [2] and improved photostability of less stable filters like [avobenzone](https://www.skinclasshub.com/theknowledgehub/ingredient-dictionary/avobenzone) [3].

### Safety and Regulatory Status

Toxicological reviews have concluded that octocrylene is **not genotoxic or carcinogenic** at concentrations allowed in cosmetics [4,5]. It is generally well tolerated, and allergic contact dermatitis has rarely been reported [4]. Some in vivo studies suggest potential **endocrine-disrupting effects, but the current evidence is not conclusive** [5].

In the EU, octocrylene is permitted in cosmetic formulations at concentrations up to 10% [5].

#### Environmental Impact

Octocrylene has been found in a wide range of aquatic environments, including swimming pools and coastal waters [1,6]:

- There is scientific evidence that octocrylene can harm certain marine invertebrates, such as sea urchins and mussels. In these species, environmental concentrations of octocrylene have been shown to exceed the 'No Observed Effect Concentration' (NOEC), which is the highest concentration at which no harmful effects are observed in toxicity tests [6].
  
- In corals, some laboratory studies have reported biological changes — like disruptions in metabolism and mitochondrial function — but these effects have not yet been confirmed in real-world reef environments. Therefore, current environmental concerns about octocrylene are based on early laboratory evidence and remain precautionary until further research is done [6].
  

### Conclusion

Octocrylene is a widely used and photostable UVB filter that plays a key role in stabilizing other filters like avobenzone. It is approved for use at up to 10% in the EU and considered safe in that range, although research is ongoing into its environmental impact.

---

### References

1. **Medici, A., Saviano, L., Siciliano, A., et al. (2022).** Octocrylene: From sunscreens to the degradation pathway during chlorination processes: Formation of byproducts and their ecotoxicity assessment. *Molecules, 27*(16), 5286.  
  [https://www.mdpi.com/1420-3049/27/16/5286](https://www.mdpi.com/1420-3049/27/16/5286)
  
2. **Choquenet, B., Couteau, C., Paparis, E., & Coiffard, L. (2008).** Development of an in vitro test to determine the water-resistance of sunscreens. *Die Pharmazie – An International Journal of Pharmaceutical Sciences, 63*(7), 494–496. 
  [https://www.ingentaconnect.com/contentone/govi/pharmaz/2008/00000063/00000007/art00009](https://www.ingentaconnect.com/contentone/govi/pharmaz/2008/00000063/00000007/art00009)
  
3. **Gaspar, L. R., & Maia Campos, P. M. B. G. (2006).** Evaluation of the photostability of different UV filter combinations in a sunscreen. *International Journal of Pharmaceutics, 307*(2), 123–128.  
  [https://pubmed.ncbi.nlm.nih.gov/16289662/](https://pubmed.ncbi.nlm.nih.gov/16289662/)
  
4. **Berardesca, E., Zuberbier, T., Sanchez Viera, M., & Marinovich, M. (2019).** Review of the safety of octocrylene used as an ultraviolet filter in cosmetics. *Journal of the European Academy of Dermatology and Venereology, 33*(Suppl 7), 25–33.  
  [https://pubmed.ncbi.nlm.nih.gov/31588614/](https://pubmed.ncbi.nlm.nih.gov/31588614/)
  
5. **Scientific Committee on Consumer Safety (SCCS). (2021).** Opinion on Octocrylene (CAS No 6197-30-4, EC No 228-250-8), Final version adopted at the plenary meeting on 30–31 March 2021. SCCS/1627/21.  
  [https://health.ec.europa.eu/document/download/2928185b-f8b7-474e-937a-052a90a90970_en](https://health.ec.europa.eu/document/download/2928185b-f8b7-474e-937a-052a90a90970_en)
  
6. **Watkins, Y. S. D., & Sallach, J. B. (2021).** Investigating the exposure and impact of chemical UV filters on coral reef ecosystems: Review and research gap prioritization. *Integrated Environmental Assessment and Management, 17*(5), 967–981.  
  [https://doi.org/10.1002/ieam.4411](https://doi.org/10.1002/ieam.4411)
  

A chemical UVB filter that is photostable and stabilizes avobenzone, but raises environmental concerns due to aquatic persistence.

Niacinamide - A versatile, well-tolerated ingredient with proven benefits for acne, pigmentation, skin barrier repair, and aging.
Farnesol - A substance that offers antimicrobial benefits but poses a risk of skin sensitization
Linalool - A fragrance compound with mild antimicrobial effects, but its oxidized forms are known skin sensitizers.
Squalane - A stable, skin-identical emollient that supports moisturization, enhances active delivery, and is well-tolerated by all skin types.
Glycerin - A powerful, skin-compatible humectant that hydrates, protects the barrier, and suits even the most sensitive skin.
Salicylic Acid - A pore-clearing exfoliant with and acne-fighting benefits.
Caffeine - A circulation-boosting compound that may help reduce the appearance of cellulite and protects against oxidative stress.
Zinc Oxide - A broad-spectrum mineral UV filter with additional skin-soothing and antimicrobial benefits.
Tocopherol - A skin-protecting antioxidant that supports the skin barrier and fights oxidative damage.
Glycolic Acid - An effective exfoliant that enhances skin texture, diminishes hyperpigmentation, and reduces signs of aging.
Avobenzone - A chemical UVA filter that uniquely protects against long-range rays up to 400 nm.
Octocrylene - A chemical UVB filter that is photostable and stabilizes avobenzone, but raises environmental concerns due to aquatic persistence.

The Knowledge Hub

Ingredient Dictionary