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Hydroquinone in skincare
Most potent OTC/prescription hyperpigmentation treatment; banned in EU and several countries.
PM use strongly preferred. Hydroquinone is photosensitizing and some formulations photodegrade under UV. AM application without thorough SPF dramatically increases irritation risk, paradoxical darkening risk (PIH), and systemic absorption. Always apply at night, followed by a broad-spectrum SPF 30+ every single morning. Some dermatologists prescribe AM and PM use under supervision. Only in strict combination with SPF.
What it is
Hydroquinone (para-dihydroxybenzene) competitively inhibits tyrosinase and is cytotoxic to melanocytes at higher concentrations. FDA-approved OTC at 2% (Rx up to 4%); prescription-only in UK. Banned for cosmetic use in EU, Australia, Japan. Safety concerns: ochronosis (paradoxical permanent darkening with prolonged high-dose use), potential mutagenicity in rodent studies at oral doses, systemic absorption increases with facial application. Limit use to 3–5 months under dermatologist supervision. Always use SPF.
The facts
| Category | Depigmenting Agent / Skin Lightener |
| Typical use | Evening |
| Concentration YARAI treats as a full dose | 0.02% |
| EU maximum permitted concentration | 0.02% (0.02% (after mixing for use)) |
| EU Cosmetics Regulation annex | II |
| EU status | prohibited |
| EU and US differ | FDA permits up to 2% OTC for skin lightening. EU has prohibited it since 2001 and will not reconsider without new SCCS-approved safety data. |
| Also listed as | quinol, 1,4-dihydroxybenzene, benzene-1,4-diol |
Why the amount matters, not just the presence
Most ingredient checkers tell you whether something is in the bottle. That is a smaller question than it sounds. Hydroquinone at 0.02% and hydroquinone at a trace level are not the same ingredient in any way that affects your skin.
An ingredient list is ordered by quantity, so position carries real information. YARAI reads that position and scores accordingly, which is why the same ingredient can land differently in two different products.
The honest limit: a list gives order, not percentages. Estimating concentration from position is an estimate. It is a better estimate than ignoring position, and it is still an estimate. We would rather tell you that than let a number look more certain than it is.
Regulatory status
Banned in EU cosmetics (Annex II). SCCS found insufficient safety data for skin-lightening use; concerns include carcinogenicity and genotoxicity.
Common questions
What does hydroquinone do in a skincare product?
Most potent OTC/prescription hyperpigmentation treatment; banned in EU and several countries.
How much hydroquinone should a product contain?
YARAI treats 0.02% as a full dose for this ingredient. Below that, the ingredient is present but is scored as contributing less. An ingredient list gives you the order of ingredients, not their percentages, so this is an estimate read from position rather than a measurement.
Is hydroquinone restricted in the EU?
The EU Cosmetics Regulation permits this ingredient up to 0.02% in leave-on cosmetics, listed under II. 0.02% (after mixing for use)
When should I use hydroquinone?
PM use strongly preferred. Hydroquinone is photosensitizing and some formulations photodegrade under UV. AM application without thorough SPF dramatically increases irritation risk, paradoxical darkening risk (PIH), and systemic absorption. Always apply at night, followed by a broad-spectrum SPF 30+ every single morning. Some dermatologists prescribe AM and PM use under supervision. Only in strict combination with SPF.
Check your own products
Point your camera at a product. YARAI identifies it from the label, finds that product's full ingredient list from published sources, and scores it. No barcode and no box needed, which is how it handles imported and small-brand products.
Concern level, category and thresholds on this page are read directly from the same data the YARAI app scores with, so this page and the app cannot disagree. EU figures cite Regulation (EC) No 1223/2009. Last built 2026-09-09. Nothing here is medical advice.