Hydroquinone
✕ EU ProhibitedIdentification
CAS Number 123-31-9
EINECS / EC 204-617-8
CosIng Ref 76687
Chemical Name benzene-1,4-diol
IUPAC Name —
Formula C6H6O2
Mol. Weight 110.11 g/mol
InChIKey QIGBRXMKCJKVMJ-UHFFFAOYSA-N
Function & Classification
Primary Function Skin Conditioning
Secondary Functions BLEACHING; HAIR DYEING; FRAGRANCE; REDUCING
Origin Synthetic
EU Regulatory Status
Max Leave-on 0.02%
Restrictions Prohibited substance under EU Regulation 1223/2009 Annex II.
Conditions of Use PROHIBITED in cosmetic products (Annex II). Professional nail hardeners only: max 0.02% under strict conditions (not for general consumer use).
Mandatory Warning PROHIBITED. Not permitted in cosmetic products for general consumer use.
SCCS Opinion View SCCS opinion →
Safety Profile
10 / 10
Skin Type Compatibility
Sensitive Skin ✕ Potential Irritant
Fungal Acne Safe ✓ Safe
Toxicology Profile
NOAEL 25 mg/kg bw/day (oral, rat) SCCS/0893/05 — PROHIBITED Annex II
Sensitization Moderate
Genotoxicity Inconclusive
Phototoxicity Non-phototoxic
Dermal Absorption 45%
LD₅₀ Oral 302 mg/kg (rat)
Skin Irritation (Draize) 2.0 / 4.0 ⚠
Eye Irritation (Draize) 2.5 / 4.0 ⚠
Source SCCS Opinion ↗
Formulation Guidelines
Usage level, pH range, solubility and addition phase not yet available.
Usage Level % · Addition Phase · Solubility
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