Cetyl Alcohol

Cetyl alcohol serves many functions in cosmetics, acting as an emollient, opacifier, stabilizer, thickener and foam boosting agent, among others. It is not irritating to the skin, but may be moderately comedogenic.

Scientific Research

Caution: Please read wisderm.com's medical disclaimer.

Table of contents:

1. Sources

Cetyl alcohol is a fatty alcohol that appears as a white, waxy solid in flake or powder form.[1] It was originally discovered in 1813 by the French chemist Michel Chevreul, who obtained it by saponifying spermaceti, a wax-like substance obtained from sperm whale head oil.[2][3]

Cetyl alcohol is a multifunctional cosmetic ingredient and is used as a emollient, emulsifier, emulsion stabilizer, foam booster, masking agent, opacifier, surfactant and viscosity control agent.[4] In 2006, cetyl alcohol was reportedly used in 2,931 cosmetic products, with data from 2005 indicating that it was included up to a concentration of 15%.[5]

Cetyl alcohol is also permitted by the US FDA as a direct and indirect food additive.[6][7]

2. Bioavailability

Cetyl alcohol has a relatively low molar mass and is oil-soluble,[1] which may enable it to pass through the stratum corneum. It has been mentioned that cetyl alcohol penetrates the skin like active substances.[8] A paper published in 1985 stated that it was unlikely that cetyl alcohol penetrates intact skin in allergicologically relevant concentrations but that a marked percutaneous absorption is expected with diseased skin.[9] Unfortunately, we were unable to obtain any further details on the experiments conducted to reach this conclusion.

Another paper described a water-in-oil microemulsion that was able to deliver cetyl alcohol into the skin 2-6 times faster and at least twice as much as 2 macroemulsion formulations, namely a cream and a lotion.[10]

Interestingly, cetyl alcohol can act as a penetration enhancer. It moderately enhanced the penetration of the pain reliever fentanyl and the vasodilator nitroglycerin, from drug-in-adhesive patches into excised rat abdominal skin in 2 separate studies.[11][12]

If cetyl alcohol is able to reach viable skin, it may be oxidized to palmitic acid by the enzyme fatty alcohol:NAD+ oxidoreductase in human fibroblasts, as has been shown to occur in vitro.[13] The palmitic acid so formed may then become part of the skin barrier, since palmitic acid is known to be a component of the epidermis.[14]

3. Effects on the skin

3.1 Increased hydration

Cetyl alcohol is said to be used as an emollient to prevent skin from drying and chapping because of its water-binding property.[1] It has also been lumped together with occlusive moisturizing ingredients such as petrolatum, lanolin and mineral oil elsewhere.[15] We were not able to find any experimental data to substantiate these claims however, save for one study which found that a combination of cetyl alcohol, isostearyl isostearate, potassium cetyl phosphate, cetyl behenate and behenic acid improved the visible signs of skin dryness more effectively than a comparable vehicle containing mineral oil.[16]

3.2 Psoriasis treatment

Cetyl alcohol has apparently been tested for its effects on psoriatic scales, but no further information was available.[17]

4. Side Effects

Cetyl alcohol was first assessed by the Cosmetic Ingredient Review (CIR) Expert Panel in 1988, which concluded that it was safe for use.[1] In 2005, the CIR Expert Panel evaluated new data that had become available since the first review, and reaffirmed its original conclusion.[5]

4.1 Dermal toxicity

When cetyl alcohol was applied full-strength to the clipped intact or abdominal skin of rabbits, one of the four animals dosed with 3.16 ml/kg (the highest dose tested) had decreased activity and laboured respiration. The acute dermal toxicity was reported to be > 2.6 g/kg in this study, and > 2 g/kg in another similar study.[1][18]

Subchronic dermal toxicity studies have also been performed. In one, 30% cetyl alcohol in methanol and propylene glycol was applied to 5 rabbits daily for 30 days, after which infiltrates of lymphomononuclear cells and histiocytes were observed in the superficial portions of the dermis.[19] 2 other studies utilized creams containing 11.5% cetyl alcohol, which was applied 5 times daily to 20 and 48 rabbits for 20 days. All the rabbits developed visible signs of exfoliative dermatitis within 2-3 days, characterized by acanthosis, parakeratosis, hyperkeratosis, and papillary projections of the epidermis.[20] A 3-month dermal toxicity study, also on rabbits, of a moisturizer containing 2% cetyl alcohol found only mild inflammation at the application site however, and no evidence of systemic toxicity.[1]

4.2 Skin irritation and sensitization

Animal studies concur that cetyl alcohol has low skin irritation potential, reporting either no irritation or only very slight to well-defined erythema, slight to mild edema and slight desquamation even when 100% cetyl alcohol was applied under occlusive conditions for 24 hours.[1]

Cetyl alcohol has also been tested extensively for its skin irritation and skin sensitization potential in humans. Of the human studies submitted to the Cosmetic Ingredient Review Expert Panel for its initial safety assessment, the vast majority were unpublished experimental data on cosmetic products such as creams, lotions, lipsticks, cleansers and conditioners, that contained low concentrations (<10%) of cetyl alcohol. All identified no or only slight irritation and/or sensitization, and 2 concluded that products containing 1% and 4% cetyl alcohol did not induce photosensitization.[1][21][22] When 82 patients in Colombia who had suspected photoallergic contact dermatitis were patch-tested, only 1 had a positive contact reaction to cetyl alcohol.[23]

Although one study analyzing the results of 3 years of patch tests in 330 dermatological patients revealed that 11.2% had allergic reactions to cetyl alcohol, the authors acknowledged that this figure was not consistent with those from other studies in the literature.[24] For example, Hjorth and Trolle-Lassen identified only 2 positive reactions among 1,664 consecutive patients,[1] while Fisher et .al. did not identify any positive reactions among 100 patients.[25] It has been suggested that the anomalously large number of positive patch tests in the first study may be due to the preferential choice of creams containing cetyl alcohol for the treatment of outpatients.[1]

This agrees with the case reports in the literature of contact allergy and contact dermatitis to cetyl alcohol, most of which were due to its presence in topical medications[26][27][28][29][30][31][32][33] and only a few of which were attributed to cetyl alcohol-containing cosmetic products.[34][35]

Paradoxically, paraffin wax in cetyl alcohol has been found to statistically significantly reduce allergic rashes produced by the oil urushiol, a condition termed Rhus allergic contact dermatitis.[36][37]

4.3 Comedogenicity

A paper published in 1989 classified cetyl alcohol as moderately comedogenic, with a grade of 2 out of 5 for comedogenicity, indicating that it caused a moderate increase in follicular keratosis when applied daily 5 days per week for 2 weeks to rabbit ear skin.[38] A more recent study also using the rabbit external ear canal found that cetyl alcohol was not comedogenic, however.[39]

4.4 No evidence of mutagenicity

Mutagenicity tests on cetyl alcohol using 5 mutant strains of S. typhimurium indicate that cetyl alcohol is not mutagenic to any of the strains, regardless of metabolic activation status.[40][41]

Scientific References

  1. Cosmetic Ingredient Review Expert Panel. Final Report on the Safety Assessment of Cetearyl Alcohol, Cetyl Alcohol, Isostearyl Alcohol, Myristyl Alcohol, and Behenyl Alcohol. Int J Toxicol. (1988)
  2. Fukushima S, Yamaguchi M. Physical Chemistry of Cetyl Alcohol: Occurrence and Function of Liquid Crystals in O/W Creams. Surface and Colloid Science, Volume 16. (2001)
  3. Mayer J, Hanson SD. Michel Eugene Chevreul - A Biographical Sketch. J Nutr. (1960)
  4. European Commission. Cetyl Alcohol. CosIng. (2014)
  5. Cosmetic Ingredient Review Expert Panel. Annual Review of Cosmetic Ingredient Safety Assessments: 2005/2006. Int J Toxicol. (2008)
  6. US Food and Drug Administration. CFR - Code of Federal Regulations Title 21, Part 172, Subpart I, Section 172.864. Code of Federal Regulations. (2013)
  7. US Food and Drug Administration. CFR - Code of Federal Regulations Title 21, Part 178, Subpart D, Section 178.3480. Code of Federal Regulations. (2013)
  8. Zesch A. Adverse reactions of externally applied drugs and inert substances. Derm Beruf Umwelt. (1988)
  9. Zesch A, Bauer E. Quantitative aspects of the percutaneous uptake of wool wax alcohols (cetyl alcohol) and paraffins (octadecane) from different ointment bases. Derm Beruf Umwelt. (1985)
  10. Linn EE, Pohland RC, Byrd TK. Microemulsion for intradermal delivery of cetyl alcohol and octyl dimethyl PABA. Drug Dev Ind Pharm. (1990)
  11. Mehdizadeh A, et. al. Effects of pressure sensitive adhesives and chemical permeation enhancers on the permeability of fentanyl through excised rat skin. Acta Pharm. (2006)
  12. Savoji H, Mehdizadeh A, Ramazani Saadat Abadi A. Transdermal nitroglycerin delivery using acrylic matrices: design, formulation, and in vitro characterization. ISRN Pharm. (2014)
  13. Rizzo WB, et. al. Fatty alcohol metabolism in cultured human fibroblasts. Evidence for a fatty alcohol cycle. J Biol Chem. (1987)
  14. Gray GM. Phosphatidyl-(N-acyl)-ethanolamine. A lipid component of mammalian epidermis. Biochim Biophys Acta. (1976)
  15. Yokota M, Maibach HI. Moisturizer effect on irritant dermatitis: an overview. Contact Dermatitis. (2006)
  16. Pennick G, et. al. The effect of an amphiphilic self-assembled lipid lamellar phase on the relief of dry skin. Int J Cosmet Sci. (2012)
  17. Kimmig J. Demonstration of cetyl alcohol in psoriasis scales. Arch Klin Exp Dermatol. (1966)
  18. Scala RA, Burtis EG. Acute toxicity of a homologous series of branched-chain primary alcohols. Am Ind Hyg Assoc J. (1973)
  19. Rantuccio F, et. al. Histological changes in rabbits after application of medicaments and cosmetic bases. Contact Dermatitis. (1979)
  20. Elliott GA, Gray JE. Morphologic effects of mildly irritating topical agents. Toxicol Appl Pharmacol. (1970)
  21. Wilkinson DS, et. al. Terminology of contact dermatitis. Acta Derm Venereol. (1970)
  22. Phillips L 2nd, et. al. A comparison of rabbit and human skin response to certain irritants. Toxicol Appl Pharmacol. (1972)
  23. Rodríguez E, et. al. Causal agents of photoallergic contact dermatitis diagnosed in the national institute of dermatology of Colombia. Photodermatol Photoimmunol Photomed. (2006)
  24. Blondeel A, Oleffe J, Achten G. Contact allergy in 330 dermatological patients. Contact Dermatitis. (1978)
  25. Fisher AA, Pascher F, Kanof NB. Allergic contact dermatitis due to ingredients of vehicles. A "vehicle tray" for patch testing. Arch Dermatol. (1971)
  26. van Ketel WG. Allergy to cetylalcohol. Contact Dermatitis. (1984)
  27. Hausen BM, Kulenkamp D. Contact allergy to fludroxycortid and cetyl alcohol. Derm Beruf Umwelt. (1985)
  28. Degreef H, Dooms-Goossens A. Patch testing with silver sulfadiazine cream. Contact Dermatitis. (1985)
  29. Schmoll M, Hausen BM. Allergic contact dermatitis to prednisolone-21-trimethyl acetate. Z Hautkr. (1988)
  30. Fraser-Moodie A. Sensitivity to silver in a patient treated with silver sulphadiazine (Flamazine). Burns. (1992)
  31. Komamura H, et. al. A case of contact dermatitis due to impurities of cetyl alcohol. Contact Dermatitis. (1997)
  32. Oiso N, Fukai K, Ishii M. Concomitant allergic reaction to cetyl alcohol and crotamiton. Contact Dermatitis. (2003)
  33. Soga F, Katoh N, Kishimoto S. Contact dermatitis due to lanoconazole, cetyl alcohol and diethyl sebacate in lanoconazole cream. Contact Dermatitis. (2004)
  34. Kiec-Swierczynska M, Krecisz B, Swierczynska-Machura D. Photoallergic and allergic reaction to 2-hydroxy-4-methoxybenzophenone (sunscreen) and allergy to cetyl alcohol in cosmetic cream. Contact Dermatitis. (2005)
  35. Aakhus AE, Warshaw EM. Allergic contact dermatitis from cetyl alcohol. Dermatitis. (2011)
  36. Zhai H, Willard P, Maibach HI. Evaluating skin-protective materials against contact irritants and allergens. An in vivo screening human model. Contact Dermatitis. (1998)
  37. Zhai H, Willard P, Maibach HI. Putative skin-protective formulations in preventing and/or inhibiting experimentally-produced irritant and allergic contact dermatitis. Contact Dermatitis. (1999)
  38. Fulton JE. Comedogenicity and irritancy of commonly used ingredients in skin care products. J Soc Cosmet Chem. (1989)
  39. Nguyen SH, Dang TP, Maibach HI. Comedogenicity in rabbit: some cosmetic ingredients/vehicles. Cutan Ocul Toxicol. (2007)
  40. Ames BN, Mccann J, Yamasaki E. Methods for detecting carcinogens and mutagens with the Salmonella/mammalian-microsome mutagenicity test. Mutat Res. (1975)
  41. Blevins RD, Taylor DE. Mutagenicity screening of twenty‐five cosmetic ingredients with the salmonella/microsome test. J Env Sci Health, Part A. (1982)