Hydroquinone works by suppressing the production of melanin, the brown substance that regulates skin pigmentation. Over time, blemishes, scars, or other colored areas fad. However, the effect is reversible; stopping treatment and exposure to sunlight can reverse the condition. Since too much hydroquinone can cause side-effects, dermatologists typically prescribe daily treatments for three to six months, followed by periods in which less frequent dosing is needed.