Related

Melanin is made in melanocytes by tyrosinase, packaged into melanosomes, and transferred to surrounding keratinocytes. An active can intervene at any of those stages.

Stage	Approach	Ingredients
Tyrosinase inhibition	Block the rate-limiting enzyme	Kojic acid, arbutin, azelaic acid, tranexamic acid, resorcinol derivatives
Antioxidant / reduction	Interrupt oxidation steps, lighten existing pigment	Vitamin C, thiamidol, glutathione (topical)
Transfer blocking	Stop melanosomes reaching keratinocytes	Niacinamide
Turnover	Shed pigmented cells faster	Retinoids, AHAs
Prevention	Stop new pigment being triggered	Sunscreen — the largest single lever

Sunscreen is not a supporting act here. UV and visible light drive the pigment being treated, and a brightening routine without daily Facial Sunscreen is a bucket with a hole in it. For melasma specifically, visible light matters, which is the argument for a tinted mineral sunscreen containing iron oxides.

Hydroquinone is the most effective topical depigmenting agent and the most restricted. In the US it was available OTC at 2% for decades under a proposed monograph that was never finalised; the CARES Act of 2020 removed OTC hydroquinone from the market, and it is now available only by prescription. The EU banned it in general cosmetics long before that — it appears in Annex II, the prohibited list, with a narrow exception for professional artificial nail systems.

The reason for the caution is exogenous ochronosis, a paradoxical blue-black discoloration seen with long-term high-concentration use, alongside irritation and ring-shaped depigmentation from misuse.

A large global market sells lightening products in a context of colourism, and it is worth stating plainly rather than skirting. Two hard facts attach to it:

• Mercury. Mercury compounds are among the eleven entries FDA specifically restricts, permitted only in eye-area products at ≤65 ppm where no other effective preservative exists. Skin-lightening creams containing mercury salts are illegal in the US and the EU, are repeatedly found in imported and online-sold products, and cause real neurological and renal harm — including to household members through secondary exposure.
• Illegal steroids. Unlabelled potent corticosteroids appear in the same market and produce skin atrophy, telangiectasia and adrenal suppression.

Buying this category from unregulated sources is the highest-risk act in consumer cosmetics. It is not a matter of efficacy but of adulteration.

Cosmetic brightening and appearance of dark spots claims keep a product in FDA primary category (14). A claim to lighten skin, to treat melasma, or to affect pigmentation as a physiological process is a drug claim, and FDA has issued warning letters on exactly that wording. Hydroquinone is prescription-only in the US and prohibited in the EU.

Antioxidant-based formulas — vitamin C above all — are the shortest-lived. Three months for unencapsulated L-ascorbic acid; six to twelve for niacinamide, arbutin, tranexamic acid and azelaic. Discoloration is the tell, and in this category discoloration is also visible: a brightening serum that has gone brown is self-refuting.

• Skincare — the shelf this sits on, and the rest of it.
• Cosmetics — what the label is legally allowed to say, and the full catalogue.
• The rest of Treating — Facial Serum · Ampoule · Facial Oil · Spot Treatment · Blemish Patch · Retinoid Treatment.
• Facial Sunscreen — the half of the routine that does the most work.
• The FDA Isn't That Great — the sceptical read on the agency policing all of this.
• Regulatory statements here follow the FDA and EU sources listed on Cosmetics, read 16 August 2026.