1,2-hexanediol
Also known as Hexane-1,2-diol, 1,2-Dihydroxyhexane, Hexylene-alpha-glycol
“CIR Expert Panel says: safe as used in cosmetics.”
1,2-Hexanediol (hexane-1,2-diol; CAS 6920-22-5; C6H14O2) is a C6 alkane-1,2-diol used in cosmetic formulations as a preservative booster, humectant, and solvent. Together with caprylyl glycol, pentylene glycol, and C15-18 glycol, it is one of the four members of the 1,2-glycol series in current cosmetic use. It is commonly combined with phenoxyethanol or organic-acid preservatives to enhance antimicrobial efficacy and enable lower total preservative loads, particularly in K-beauty-style lightweight essences and serums. The Cosmetic Ingredient Review Expert Panel reviewed 1,2-hexanediol and 15 other 1,2-alkane-diols and concluded they are safe in the present practices of use and concentration described in the assessment (Johnson, Bergfeld, Belsito et al., Int J Toxicol 31(5 Suppl):147S-168S, 2012, PMID 23064773). The Panel noted dermal absorption of 1,2-glycols occurs but decreases for longer-chain members of the series; 1,2-hexanediol sits in the middle of the series (C6), and combined with negative oral toxicity and genotoxicity data on the shorter-chain homologues the Panel judged the safety margin adequate. The QRT row carries no conditions or concentration limits.
Preservative booster that enhances phenoxyethanol and organic-acid preservative efficacy, enabling lower total preservative concentrations
Humectant and solvent that improves lightweight formulation texture; commonly used in Korean-beauty toners, essences, and watery serums
CIR Expert Panel concluded safe as used in cosmetics (Johnson et al., IJT 2012, PMID 23064773) — same assessment clears caprylyl glycol, pentylene glycol, and C15-18 glycol
Intermediate chain length in the 1,2-glycol series means more favorable dermal absorption profile than shorter homologues like 1,2-butanediol
- · No documented concerns at typical cosmetic use levels; contact allergy reports are uncommon compared with ethylhexylglycerin
Small aliphatic diols (including 1,2-hexanediol) are dermally absorbed; the CIR 2012 assessment relied on modeling and homologue toxicity data rather than dedicated dermal kinetics studies on 1,2-hexanediol itself
CIR Quick Reference Table (12/2017, revised 07/2018) - 1,2-Hexanediol row: Finding 'S' (Safe), Citation 'IJT 31(S2):147-168, 2012'
“1,2-Hexanediol | S | [no detail column entry] | IJT 31(S2):147-168, 2012”— QRT-122017revised072018.pdf, p. 1