active

Hydroquinone

INCI: HYDROQUINONE

CAS 123-31-9 EC 204-617-8

Hydroquinone

Limited Data

Insufficient safety data available. Consider enriching this ingredient.

Details

Description

Hydroquinone

Purpose

Function

Tyrosinase inhibitor; competitive inhibitor and cytotoxic agent to melanocytes; inhibits both melanin synthesis and DNA synthesis in melanocytes; benchmark for all modern depigmenting actives

Profile

Properties

Silicone

Silicone free

Compliance

Regulatory Status

Banned

Safety

POOR

Restricted

Absorptionhigh

Sensitizationhigh

MoSnot established

NOAEL25 mg/kg

ConcernHigh

Flags

eu-bannedannex-ii-prohibitedus-prescription-onlycares-act-2020rx-4pct-usochronosis-riskleukoderma-riskcytotoxiccarcinogenicity-concernmutagenicity-concernpara-benzoquinone-intermediatebanned-japan-australia-nzbenchmark-onlynot-for-cosmetic-formulationavoidminamata-public-health-concernendocrine_disruptoreu_banned_cosmeticseu_cosing_listed

Verdict

Hydroquinone is a historical gold-standard depigmenting agent now prohibited in EU cosmetics and restricted to prescription-only in the US due to unacceptable risk profile including exogenous ochronosis, leukoderma, and potential carcinogenicity; modern alternatives offer superior safety with comparable efficacy.

US Note

Reclassified from OTC to prescription-only under MoCRA/CARES Act 2020. FDA has not issued final Rx rule; interim: OTC products without NDA receive warning letters. CIR concluded safe at ≤1% in rinse-off only. Rx 4% available under physician supervision. Saudi Arabia 2025 study found HQ in 80% of unregulated skin-lightening samples despite prescription restrictions. Banned or Rx-only in Japan, Australia, New Zealand, and multiple African and Asian markets.

Assessment

Ratings

Comedogenic0/5

LowHigh

Irritancy0/5

LowHigh

Reference

Identifiers

CAS Number

123-31-9

EC Number

204-617-8

INCI

HYDROQUINONE