Thioglycolic Acid

Benefits
Body Hair Removal

What is Thioglycolic Acid?

Thioglycolic acid, chemically known as mercaptoacetic acid, is a synthetic organic compound featuring a thiol (-SH) group linked to a carboxylic acid backbone (HS-CH2-COOH). It belongs to the class of reducing agents commonly found in hair care and depilatory cosmetics. In products like cream hair removers, it functions by penetrating the hair shaft and cleaving the disulfide cross-links in keratin proteins, which softens and dissolves hair at the skin surface for easy wipe-off removal. In hair waving or straightening treatments, it similarly disrupts these bonds, allowing hair to be reshaped before an oxidizing step locks in the new form. Its antioxidant role involves scavenging free radicals to preserve formulation stability against oxidation. Formulations balance its activity with alkaline pH and limit concentrations to manage reactivity on skin.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 2-5 View on EWG →
PubChem View on PubChem →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Antioxidant
Slows oxidation of oils, fragrances, and sensitive actives to improve shelf life and reduce rancidity or color change; sometimes also supports skin protection from oxidative stress.
Depilating agent
Chemically breaks down hair’s keratin structure (commonly via thiol chemistry) to enable painless hair removal at the skin surface in depilatory creams.
Hair waving or straightening
Reshapes hair by breaking and reforming bonds in the fiber (often via reducing/oxidizing steps), enabling permanent waves or straightening services/products.
Reducing agent
Causes reduction reactions, often used in hair perming.

Benefits

Facilitates painless surface-level body hair removal by weakening hair structure.

Enables reshaping of hair fibers for waving or straightening effects.

Helps maintain product stability as an antioxidant against oxidation.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Individuals looking for chemical hair removal alternatives to shaving or waxing.
Those with sensitive or compromised skin barriers.
People undergoing professional hair perming or straightening services.
People experiencing thiol or sulfide sensitivities.
Users of formulations where oxidation protection extends shelf life.
Individuals with open wounds or recent skin treatments in application areas.

Safety Notes

  • Follow product instructions including patch testing to assess tolerance.
  • Rinse thoroughly if contact occurs with eyes or mucous membranes.

Frequently Asked Questions about Thioglycolic Acid

What does thioglycolic acid do in cosmetics?

It acts as a reducing agent to break disulfide bonds in hair keratin, aiding removal or reshaping.

Is thioglycolic acid safe for skin?

Safe in regulated cosmetic uses with precautions like patch testing due to irritation potential.

Can it clog pores?

Rated non-comedogenic, unlikely to contribute to pore blockage.