murphyThioglycolic Acid
AKA: Mercaptoacetic acid, 68-11-1, 2-Mercaptoacetic acid, Sulfanylacetic acid, 2-Thioglycolic acid, Thioglycollic acid, Acetic acid, Thiovanic acid, Mercaptoessigsaeure
Synthetic
Antioxidant
Acid
Not Clean
OriginSynthesized from mercaptoacetic acid, a compound in the thiol chemical family containing a sulfhydryl group. Produced through the reaction of chloroacetic acid with sodium hydrosulfide under controlled conditions.
Based on the available data, the CIR Expert Panel concluded that ... Thioglycolic Acid is safe for use in hair straighteners, permanent waves, tonics, dressings, and so forth, wave sets, other non-coloring hair products, and hair dyes and colors, as described in this safety assessment, at concentrations up to 15.2% (as Thioglycolic Acid). Hairdressers should avoid skin contact and minimize consumer skin exposure. ... Thioglycolic Acid in depilatories is safe when formulated to be non-irritating under conditions of recommended use.
Solubility greater than or equal to 100 mg/mL at 64 °F (NTP, 1992)
Formula
C2H4O2S
Mol. Weight
92.12
CAS #
68-11-1
Form
Liquid
State
Thioglycolic acid appears as a colorless liquid with an unpleasant odor. Density 1.325 g / cm3. Used to make permanent wave solutions and depilatories. Corrosive to metals and tissue.
Skin Types
●all-skin-types
Best For
Uneven Texture
Pregnancy & Breastfeeding Safe
Caution
Functions
Antioxidant
Fights free radicals — the unstable molecules from UV, pollution, and stress that break down collagen and cause premature aging.
Depilatory
Hair Waving Or Straightening
Reducing
Supports cell turnover
Smooths skin texture
Brightens uneven skin tone
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
6
CIR
Safe as used
Pregnancy
Caution
CIR Safety Findings
Not a Sensitizer
4 studies / 4 not sensitizing (CIR 128)
Mixed Skin Irritation Results
6 studies / 3 irritating / 1 mixed / 2 not irritating / reactions slight to corrosive (CIR 128 and 347)
Concentration Guide
0%50%100%
Reg. limit 14.4%
EU/SCCS limit: 14.4% in cosmetic products. Opinion: SCCS/1520/13
Regulatory Agencies
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR