Octyldodecanol
Also known as 2-Octyldodecanol, 2-Octyldodecan-1-ol, C20 branched fatty alcohol
“CIR Expert Panel says: safe as used in cosmetics.”
Octyldodecanol (2-octyldodecan-1-ol, CAS 5333-42-6) is a branched C20 fatty alcohol used as an emollient and solvent in cosmetics. The CIR Expert Panel assessed it as safe (Finding=S, no conditions) under JACT 4(5):1-29, 1985, with the finding confirmed in 03/2004 and an updated assessment published in IJT 25(S2), 2006. Notably, unlike straight-chain fatty alcohols (cetyl, stearyl, behenyl), octyldodecanol has a documented patch-test literature showing ingredient-specific allergic contact dermatitis: case reports in Contact Dermatitis and Clinical and Experimental Dermatology identify octyldodecanol as the causative allergen in antifungal creams, anti-itch preparations, and anti-aging cosmetics (PMIDs 9165214, 12653724, 17441857). This distinguishes it from the broader fatty alcohol class where sensitization is typically impurity-driven. A 2006 permeation study with transdermal patches (PMID 16880631) measured mild primary irritation indices (1.29-1.46 vs. 0.21 control) in animal models, consistent with mild irritant potential at pharmaceutical patch concentrations.
Emollient, spreading agent, and solvent with excellent compatibility across skin, lip, and hair care formulations
CIR Expert Panel found safe as used in cosmetics:1-29, 1985; confirmed 03/04; IJT 25(S2), 2006)
Branched chain structure provides lighter skin feel and better spreadability than equivalent straight-chain fatty alcohols; low polarity and good solubilizing properties make it effective for fragrance and active solubilization
Long history of cosmetic use at typical concentrations of 1-20%; EWG hazard rating of 1 (low concern)
Patch-test-confirmed allergic contact dermatitis to octyldodecanol specifically (not attributed to impurities): documented in clotrimazole cream (Dharmagunawardena & Charles-Holmes 1997, PMID 9165214), anti-itch cream (Singh et al. 2007, PMID 17441857), and as the cause of genital swelling (Dawn & Forsyth 2003, PMID 12653724)
Mild primary irritation indices measured in animal transdermal patch models at pharmaceutical patch concentrations (Kakubari et al. 2006, PMID 16880631); relevance to typical leave-on cosmetic concentrations is uncertain
CIR Quick Reference Table (12/2017, revised 07/2018) — Octyldodecanol row: Finding=S, Citation=JACT 4(5):1-29, 1985 confirmed 03/04; IJT …
“Octyldodecanol | S | [no detail column entry] | JACT 4(5):1-29, 1985 confirmed 03/04; IJT 25(S2), 2006”— QRT-122017revised072018.pdf, p. 79