hydroquinone

Hydroquinone, also known as 1,4-dihydroxybenzene, is an aromatic organic compound with the formula C6H4(OH)2. It appears as a colorless to pale white crystalline solid that can sublimate at moderate temperatures. It occurs in trace amounts in some natural products but is produced industrially for commercial use. It is the reduced form of benzoquinone and serves as a building block and reducing agent in various chemical processes.

In industry, hydroquinone is used as an antioxidant and stabilizer for certain polymers and as a reducing agent in organic synthesis. It has also historically been used in photography as a developing agent and as a starting material for the synthesis of other chemicals, including dyes and pigments.

In dermatology, hydroquinone is used as a depigmenting or skin-lightening agent. It inhibits the enzyme tyrosinase, which is involved in melanin production, and is prescribed or formulated for treatment of hyperpigmentation such as melasma, age spots, and post-inflammatory hyperpigmentation. Usage guidelines vary by country, with some jurisdictions allowing over-the-counter products at low concentrations and others restricting or banning non-prescription use due to safety concerns.

Safety and regulation: Hydroquinone can cause irritation and contact dermatitis in some individuals. Prolonged use has been associated with ochronosis, a bluish-black skin discoloration that can be difficult to reverse. Because of safety concerns, many regulatory agencies regulate its cosmetic use, with restrictions or bans on non-prescription products in some regions and medical supervision recommended in others.

Environmental and handling considerations: It is hazardous to aquatic life with potential persistence. Proper handling, storage, and disposal as a chemical reagent are advised to minimize exposure and environmental impact.