Ingredients Glossary / H

Hydroquinone

A potent depigmenting medicine used for stubborn pigmentation; available on prescription or from a pharmacy, depending on the country, not in cosmetic skincare.

hydroquinone, HQ, 1,4-dihydroxybenzene, benzene-1,4-diol, quinol

Pigmentation & dark spots

    What it does

    Hydroquinone is a potent depigmenting medicine used for stubborn pigmentation. Depending on the country and strength, it is available on prescription or from a pharmacy, and it isn't used in cosmetic skincare. It can irritate the skin, and doctors usually prescribe it in limited courses, with breaks in between. Daily sun protection is essential while using it, as UV exposure quickly undoes results and triggers new pigment.

    How it works

    A medicine rather than a cosmetic ingredient, hydroquinone is itself a phenolic compound. It blocks tyrosinase, the enzyme pigment cells (melanocytes) use to make melanin, and at higher strengths it also slows the pigment cells themselves. Any change is gradual, and pigment can return once treatment stops, especially without strict sun protection. Arbutin, a much gentler brightener, is a hydroquinone molecule bound to a sugar; EU and Australian rules cap how much of it can be used.

    MG says

    A potent tyrosinase inhibitor, hydroquinone should only be used under strict guidance from a doctor or dermatologist, and avoided during pregnancy and breastfeeding. Gentler everyday options include tranexamic acid, azelaic acid, vitamin C and niacinamide. For stubborn pigmentation, we offer the Cosmelan and Dermamelan depigmentation treatments in the studio, and Biologique Recherche's PIGM 400 range is formulated for uneven tone without hydroquinone.

    Cautions

    Use hydroquinone only as prescribed or directed by your doctor or pharmacist. It can cause redness, dryness and stinging, and prolonged or unsupervised use has been linked to ochronosis, a rare, stubborn blue-grey darkening of the skin. Avoid it during pregnancy and breastfeeding. Wear SPF daily, and steer clear of unregulated creams bought online, which can contain undeclared hydroquinone.

    Regional notes

    Australia: Hydroquinone skin products are medicines: pharmacy-only at 2% or less, and prescription-only above that.

    United States: Hydroquinone has been prescription-only since September 2020, when the CARES Act ended legal over-the-counter sales.

    United Kingdom: Hydroquinone isn't permitted in cosmetic skincare and is available only as a prescription medicine.