Possible side effects include redness, dryness, peeling, itching, burning, and irritation at the application side. Hydroquinone may produce exogenous ochronosis, a blue-black discoloration of the skin. The risk of ochronosis increases with prolonged use of hydroquinone and continued sun-exposure. To avoid this, periodic breaks from hydroquinone are needed. Always make sure to follow your doctor’s instructions on use. There have been no reported incidences of cancer from topical application of hydroquinone in humans. Though health concerns are related to oral ingestion of hydroquinone, concerns over topical toxicity and carcinogenesis have been raised but not validated when the product is used correctly as directed under the supervision of an appropriately trained, licensed physician.
This is not a complete list of side effects and others may occur. Contact your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.