Dermatologists have long considered hydroquinone the most effective medication for treating skin discoloration. Recent studies have caused some to question its safety. Most still consider it safe for temporary use, but long-term use is associated with serious side effects.
Hydroquinone is a skin-lightening agent used in topical creams to reduce unwanted pigmentation. It works by inhibiting the production of tyrosinase, an enzyme used in the synthesis of melanin, or dark skin pigment. It doesn't bleach the existing skin pigment but stops new dark pigment from forming.
Hydroquinone products range in strength from half a percent up to eight percent, but the most common strengths are two or four percent. To use hydroquinone, rub the product on the affected area once a day. Hydroquinone is intended for use on relatively small areas of discoloration. Using it as an all-over skin lightener increases your risk of serious side effects.
Hydroquinone works by stopping new melanin from forming. This means you won't see results from the product until the old melanin in your skin has worked its way to the surface and been sloughed off as dead skin cells. This process can take six to eight weeks.
After about four months, you should begin to taper off from daily use of hydroquinone. You may go down to three times a week for a maintenance period and eventually stop use altogether. Most cases of serious side effects happened when patients used the product for longer periods, sometimes for years.
Common side effects of hydroquinone include irritation, redness or burning of the treated skin. This can be worse if you combine hydroquinone with a product such as alpha-hydroxy to speed the process of sloughing dead skin cells.
Ochronosis is a potentially more serious side effect of hydroquinone. This condition causes areas of dark blue or black pigmentation on the skin. It's generally only seen in patients who use hydroquinone for long term use and over large areas of the body. Higher strengths of the medication increase your risk.
Some studies showed that mice exposed to high doses of hydroquinone developed cancer. This is probably not a concern at the concentrations generally prescribed, but it requires more study. Long-term use at higher concentrations is probably not wise.
In 2006, the U.S. Food and Drug Administration proposed a ban on over-the-counter sales of products containing hydroquinone. Under the ban, these products would have to apply for approval with the FDA as a new drug and go through a rigorous testing process. If you want to use hydroquinone for your skin pigmentation problems, discuss it with your doctor and get a prescription. Given the uncertainty surrounding the use of hydroquinone, this is probably safer.