Methyl Thioglycolate
AKA “2365-48-2, Methyl mercaptoacetate, Methyl 2-mercaptoacetate, Thioglycolic acid methyl ester, Methylthioglycolate, Acetic acid, mercapto-, methyl ester, 2-mercapto-, Methanethiol, methoxy-, Methylmercaptoacetate
Ingredient
Ingredient Facts
Methyl thioglycolate
AKA: 2365-48-2, Methyl mercaptoacetate, Methyl 2-mercaptoacetate, Thioglycolic acid methyl ester, Methylthioglycolate, Acetic acid, Mercapto-, Methyl ester, 2-mercapto-, Methanethiol, Methoxy-, Methylmercaptoacetate
Ingredient · Hair Waving Or Straightening · EWG: 4
Synthetic
Not Clean
Based on the available data, the CIR Expert Panel concluded that ... Methyl Thioglycolate 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.
Formula
C3H6O2S
Mol. Weight
106.15
CAS #
2365-48-2
Form
Liquid
State
Colorless liquid with a stench; [MSDSonline]
See origin →
Functions
Hair Waving Or Straightening
Anti-Aging Benefits
Antioxidant Protection
Reduces Inflammation
Changes hair texture
Traditional Use
Developed in the mid-20th century as a chemical depilatory and permanent wave setting agent. Created to replace safer but less effective historical hair-removal methods like sulfides and lyes.
Skin Types
all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
EWG
4
CIR
Safe as used
Pregnancy
Caution
CIR Safety Findings
medical-approval
all-shades-safe
Mild Irritant
Regulatory Status
USApermitted
EUpermitted
JAPANpermitted
CANADApermitted
RIFM fragrance ingredient safety assessment, pentanedioic acid, 1,5-dimethyl ester, CAS Registry Number 1119-40-0.
Api AM, Belsito D, Botelho D, Browne D, Bruze M et al.
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2018
Safety Assessment of Tetrasodium Glutamate Diacetate and Beta-Alanine Diacetic Acid as Used in Cosmetics.
Burnett CL, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2025
Safety Assessment of Tetrasodium Glutamate Diacetate and Beta-Alanine Diacetic Acid as Used in Cosmetics.
Burnett CL, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2025
Sodium Dehydroacetate and Dehydroacetic Acid.
Cherian P, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2024
Sodium Dehydroacetate and Dehydroacetic Acid.
Cherian P, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2024
Final Report on the Safety Assessment of 4-Methoxy-m-Phenylenediamine, 4-Methoxy-m-Phenylenediamine Sulfate, and 4-Methoxy-m-Phenylenediamine-HCI
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of Sodium Dehydroacetate and Dehydroacetic Acid
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Safety Assessment of Tetrasodium Glutamate Diacetate and Beta-Alanine Diacetic Acid as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Sodium Dehydroacetate and Dehydroacetic Acid
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Acetic Acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
Beta-Alanine Diacetic Acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
dehydroacetic acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
Methyl Thioglycolate
European Commission
EU Cosmetic Ingredient Database (CosIng)
Acetic acid and the skin: a review of vinegar in dermatology.
Elhage KG, St Claire K, Daveluy S
International journal of dermatology, 2022
Acetic acid and the skin: a review of vinegar in dermatology.
Elhage KG, St Claire K, Daveluy S
International journal of dermatology, 2022
Acetic Acid
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
dehydroacetic acid
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Potential application of novel liquid crystal nanoparticles of isostearyl glyceryl ether for transdermal delivery of 4-biphenyl acetic acid.
Fujii MY, Asakawa Y, Fukami T
International journal of pharmaceutics, 2020
Preparation of (13)C-labeled ceramide by acetic acid bacteria and its incorporation in mice.
Fukami H, Tachimoto H, Kishi M, Kaga T, Waki H et al.
Journal of lipid research, 2010
1-Methoxy-2,4-diaminobenzene and its salts
Health Canada
Health Canada Cosmetic Ingredient Hotlist
1-Methoxy-2,5-diaminobenzene and their salts
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4-Methoxy-m-phenylenediamine and its sulfate salts
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4-Methoxy-m-phenylenediamine-HCl
Health Canada
Health Canada Cosmetic Ingredient Hotlist
Trichloroacetic acid
Health Canada
Health Canada Cosmetic Ingredient Hotlist
Synthesis of mixed esters of ascorbic acid using methyl esters of palm and soybean oils.
Hsieh HJ, Chen JW, Giridhar R, Wu WT
Preparative biochemistry & biotechnology, 2005
[Pharmacological studies of N-(2-mercapto-2-methylpropionyl)-L-cysteine (SA 96). VI. Effects on vitamin B6, metals and skin collagen in rats].
Yamauchi H, Morikawa K, Kuwano M, Hikida M, Fujimura K et al.
Nihon yakurigaku zasshi. Folia pharmacologica Japonica, 1985
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR