Butylene Glycol
Also known as 1,3-Butanediol, 1,3-Butylene glycol, Butane-1,3-diol, beta-Butylene glycol
“CIR Expert Panel says: safe as used in cosmetics.”
Butylene Glycol (1,3-butanediol; CAS 107-88-0; C4H10O2) is a small aliphatic diol used in cosmetic formulations as a humectant, emulsifier, plasticizer, and solvent — often as a less-greasy alternative to glycerin or propylene glycol in hydrating toners, essences, and lightweight moisturizers. The Cosmetic Ingredient Review Expert Panel assessed butylene glycol together with hexylene glycol, ethoxydiglycol, and dipropylene glycol and concluded all four glycols are safe as cosmetic ingredients in the present practices of use (J Am Coll Toxicol 4(5):223-48, 1985; reaffirmed without reopening the assessment in 2004, republished Int J Toxicol 25(Suppl 2):1-26, 2006). Acute, subchronic, and chronic oral, parenteral, inhalation, and cutaneous toxicity studies across multiple animal species demonstrated a low order of toxicity. Butylene glycol produced only minimal to mild skin irritation in rabbit patch tests and mild to severe ocular irritation in rabbit eye tests (the latter shared with other low-MW glycols and not a concern for leave-on skin contact). The QRT row carries no conditions or concentration limits.
Humectant that draws and retains moisture in the stratum corneum with a lighter, less-greasy skin feel than glycerin
Solvent and emulsifier that improves the penetration and spreadability of water-soluble actives in hydrating formulations
CIR Expert Panel concluded safe as used in cosmetics:223-48, 1985; reaffirmed 2004)
Small aliphatic diol with a long history of safe cosmetic use; the same CIR assessment also clears hexylene glycol, ethoxydiglycol, and dipropylene glycol
- · Minimal to mild skin irritation observed at high concentrations in rabbit patch tests; not a clinical concern at typical cosmetic use levels (CIR 1985)
- · Mild to severe ocular irritation in rabbit eye tests — standard caution for avoiding direct eye contact shared with other low-MW glycols
CIR Quick Reference Table (12/2017, revised 07/2018) - Butylene Glycol row: Finding 'S' (Safe), Citation 'JACT 4(5):223-48, 1985 confirme…
“Butylene Glycol | S | [no detail column entry] | JACT 4(5):223-48, 1985 confirmed 02/04 IJT 25(S2):1-26, 2006”— QRT-122017revised072018.pdf, p. 14