Hydroquinone

Also known as: HQ, 1,4-dihydroxybenzene, Tri-Luma (in triple combination)

Hydroquinone is the reference-standard skin lightener, used for melasma and stubborn dark patches for over 50 years. Meta-analyses of randomized trials consistently rank hydroquinone alone, and especially triple combination cream (hydroquinone plus tretinoin plus a corticosteroid), as the most effective self-applied melasma treatments. It moved to prescription-only status in the US in 2020, reflecting real but manageable risks: irritation, rebound pigmentation, and rare ochronosis (a paradoxical blue-black darkening) with prolonged unsupervised use.

How it works

Hydroquinone blocks tyrosinase, the rate-limiting enzyme in melanin production, and is mildly toxic to overactive melanocytes. Pigment fades over weeks as existing melanin is shed and less new pigment is made. Because it suppresses rather than removes pigment cells, patches typically return if treatment stops and sun exposure continues.

What the evidence says, claim by claim

These are the results measured in studies, not the results shown in ads. Where the research is weak, the grade says so.

For melasma

Strong evidence

A 2022 meta-analysis of randomized, investigator-blinded trials found hydroquinone and triple combination cream effective at lightening melasma, with the triple combination consistently outperforming monotherapies. A 2020 evidence-based review covering 113 studies and 6,897 participants reached the same conclusion: triple combination cream is the most effective topical treatment, with hydroquinone alone close behind. Typical regimens are 4% once or twice daily for 8 to 12 weeks.

Multiple randomized controlled trials or a meta-analysis support this use. The effect is real and repeatable.

Self-applied topical interventions for melasma: a systematic review and meta-analysis of data from randomized, investigator-blinded clinical trials (British Journal of Dermatology, 2022; meta-analysis)
Melasma Treatment: An Evidence-Based Review (American Journal of Clinical Dermatology, 2020; systematic-review)

For dark spots and hyperpigmentation

Moderate evidence

For post-inflammatory hyperpigmentation, hydroquinone remains a first-line agent in systematic reviews of treatment in skin of color, but outcome data are humbling: across the 2024 JEADV review of PIH treatments, topicals achieved complete clearance in only 5.4% of patients, with partial improvement in about 72%. It lightens marks; it rarely erases them, and marketing that promises full removal overshoots the data.

Randomized trials support this use, but they are few, small, or short. The effect is probably real. The size of it is less certain.

Treatment of Post-Inflammatory Hyperpigmentation in Skin of Colour: A Systematic Review (Journal of Cutaneous Medicine and Surgery, 2024; systematic-review)
Post-inflammatory hyperpigmentation: A systematic review of treatment outcomes (Journal of the European Academy of Dermatology and Venereology, 2024; systematic-review)

Risks and what can go wrong

Common: irritation, redness, and contact dermatitis (in the Espinal-Perez trial, side effects hit 68.7% of hydroquinone-treated sides versus 6.2% for vitamin C). Rare but serious: exogenous ochronosis with long, high-dose, unsupervised use, seen mostly with unregulated products in darker skin. Standard practice caps continuous use at 3 to 4 months followed by a break or maintenance switch. Avoid in pregnancy and breastfeeding because a relatively large fraction is absorbed systemically. Halo depigmentation of surrounding normal skin can occur with sloppy application.

The practical details

Prescription-only in the US since 2020, typically 4% cream alone or in Tri-Luma (fluocinolone 0.01%, hydroquinone 4%, tretinoin 0.05%). Applied nightly to affected patches only, always with strict daily broad-spectrum sunscreen, without which treatment fails. Dermatologists usually cycle it: 12 weeks on, then transition to azelaic acid, tranexamic acid, or other maintenance agents.