Common Name(s): Thiol/sulfide reducing agent,keratin disulfide reducer,perm or depilatory active

CAS Number: N/a

DESCRIPTION

What It Does: Reduces cystine disulfide crosslinks in keratin allowing hair reshaping (perm) or shaft dissolution (depilatory) through thiol-disulfide exchange chemistry.

Why It's Used: Eu annex iii regulates thioglycolate perm actives (8% max) and depilatory metal sulfides at specific concentrations and ph ranges — functional concentration must be balanced against skin safety within regulatory limits.

How It Works: Thiolate (rs⁻) at alkaline ph attacks cystine disulfide: rs⁻ + ker-ss-ker → ker-s-sr + ker-s⁻ → 2 ker-sh. complete disulfide reduction at ~ph 9 with thioglycolate allows hair cortex protein chain movement for reshaping. metal sulfides (s²⁻) hydrolyse to h₂s at alkaline ph providing stronger, faster reduction for depilatory dissolution.

Typically Found In: Permanent waves,depilatories

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Typical Concentration Range: Per eu annex iii limits

SOURCING & ETHICS

Vegan Status: Yes

Halal Status: Yes

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Eu annex iii: ammonium thioglycolate max 8% at ph 7–9.5 for perm; 5% at ph 7–12.7 for depilatory. calcium thioglycolate hydroxide and strontium sulfide restricted to depilatory use at defined concentrations.

Last Verified: Cosing database,eu annex iii perm depilatory reducing agent

Primary Sources: 2026-03-12