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How much hydroquinone do you need? 4%+

The effective hydroquinone percentage, by the vehicle-controlled trials, starts at 4%; no published dose comparison sets a ceiling.

Reckon on four to eight weeks. No trial pins the exact point down; that is the standard clinical expectation.

how it was measured

Measured on Visible lightening of melasma and hyperpigmented patches, investigator-graded (MASI); the clinical consensus; no trial pins the point.

See it on the timeline, beside the others →

Written by Maya Faour, founder and sole writer; not a dermatologistHow we work →Published Reviewed

Dose line for Hydroquinone: the trials worked from 4% with no measured ceiling; ticks at 2%, 4%, 5% where the named trials worked; the highest dose tested 5% in a melasma cream with 0.1% tretinoin and 1% hydrocortisone, applied twice a week (Kang 1998): more irritation; banned from EU cosmetics. Linear scale.2%, Wattanakrai 20224%, Haddad 20035%, the highest dose tested in leave-on use on human skin (Kang 1998): more irritation2%4%5%, combinedmore irritationWattanakrai 2022Haddad 2003highest tested, Kang 19980%

2%, Wattanakrai 2022.

2% has no vehicle-controlled trial: against 1.4% silymarin it cut mMASI 18% in 3 months, split-face in 23 completers (Wattanakrai 2022).

The rose band is where the vehicle-controlled trials worked, open to the right because no dose comparison sets a ceiling; each tick is a concentration a named trial used, with its author and year; the last tick is the highest dose tested in leave-on use on human skin, 5% in a melasma cream with 0.1% tretinoin and 1% hydrocortisone, applied twice a week (Kang 1998), where the paper reports: more irritation; the regulator’s answer is a ban, so there is no line to draw; no product in our catalogue declares a percentage on the name. The scale is linear.

What hydroquinone percentage is effective?

Floor 4%: 4% hydroquinone cream beat placebo cream on the opposite side of the face in 25 completers with melasma over 3 months, 76.9% improvement as two observers graded it, with 25% side effects (Haddad 2003, double-blind), and beat placebo on MASI and mexameter in a three-arm trial of 45 Filipinos over 8 weeks, with the steepest fall between weeks 2 and 6 (Mendoza 2014).

4%+

The trials, and what they used
  • 2% has no vehicle-controlled trial: against 1.4% silymarin it cut mMASI 18% in 3 months, split-face in 23 completers (Wattanakrai 2022).
  • No comparison of 2% with 4% found.
  • The ceilings are regulatory: banned from EU cosmetics (Annex II, 0.02% in nail systems only), 2% over-the-counter products withdrawn in the US in 2020 with 4% kept on prescription, and the cosmetic safety panel against any leave-on use (Andersen 2010).

Is more than 4% hydroquinone better?

Nobody has measured it: no published dose comparison sets a ceiling for hydroquinone, so a percentage above 4% is above the trials' floor, not above a measured maximum. The highest dose tested in leave-on use was 5% in a melasma cream with 0.1% tretinoin and 1% hydrocortisone, applied twice a week (Kang 1998), and the paper reports more irritation there.

To minimize unavoidable side effects (erythema or peeling), we applied RHQ twice a week instead of the usual daily application.

The highest dose tested, in the paper’s words
  • To minimize unavoidable side effects (erythema or peeling), we applied RHQ twice a week instead of the usual daily application.

No published dose comparison sets a ceiling for hydroquinone. A declared percentage above 4% is above the trials' floor, not above a measured maximum: the trials say from 4% it works, and say nothing about whether more does more.

What does the hydroquinone percentage on a label tell you?

A name that states a percentage ("Hydroquinone 4%") is the only amount a cosmetic label ever declares, so it is the one number that can be read against the trials: at or above the 4% floor, or below it.

A name without a percentage leaves the position. The rules make a brand list ingredients in descending order of amount down to 1%, and in any order below it, so hydroquinone above the 1% line is at least 1% and hydroquinone below it can be any trace the brand likes. The floor the trials worked from is 4%, and a position alone cannot tell you whether a label reaches it.

The hydroquinone percentages in our catalogue

No product in our catalogue is sold on hydroquinone yet.

Read on

Other actives with a dose the trials pinned:

The range column was researched and verified in September 2026 (this row last changed 22 September 2026). The number is the trials' and the reasoning is the knowledge base's; neither is advice about your skin. How we score.