Cited skincare — every flag names its source, no upsell.What it does
Hydroquinone inhibits tyrosinase, the rate-limiting enzyme in melanin synthesis. Effective for melasma and post-inflammatory hyperpigmentation, typically used in 2–4% formulations. Use is time-bounded — extended continuous use risks rebound pigmentation and exogenous ochronosis (paradoxical darkening). Published cycling guidance runs roughly 3–4 months on, 2 months off [H4]; your prescriber sets yours.
The evidence, graded
expert consensusHydroquinone-treated skin is more prone to UV-driven pigmentation. Daily broad-spectrum SPF 30+ is required during use; without it, hyperpigmentation can rebound worse than baseline.Schwartz 2023 · StatPearls [Internet] ↗ expert consensusHydroquinone is absorbed through skin at 35–45% — much higher than most topicals. Pregnancy and breastfeeding guidance is to avoid it, even though existing studies have not shown harm.Bozzo 2011 · Canadian Family Physician ↗ expert consensusHydroquinone shows pigmentation reduction in 4–8 weeks. Use in cycles of 3–4 months on followed by 2 months off; continuous long-term use risks rebound hyperpigmentation and exogenous ochronosis.Sarkar 2014 · Indian Dermatology Online Journal ↗ Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
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