Mequinol is a chemical compound used in the pharmaceutical and cosmetic industries. It is a skin lightening agent that inhibits melanin synthesis and employs depigmenting activity. Mequinol is also used to treat hyperpigmentation disorders like melasma. 

Mequinol is a common active ingredient in topical drugs used for skin depigmentation. It is often mixed with a topical retinoid. Mequinol is the main alternative prescription alternative to hydroquinone. 

Mequinol can cause redness or dryness of the skin. Some cases have also been reported where using hydroquinone developed ochronosis, which are papules with bluish-black pigmentations. 

Mequinol and tretinoin combination solution is used together with a comprehensive skin care and sun avoidance program to treat areas of the skin that have become darker after repeated exposure to the sun. These areas are called solar lentigines, or age or liver spots.