An update on the safety of hydroquinone.

Hydroquinone has been used for years for multiple conditions, including melasma, post-inflammatory hyperpigmentation, dyschromia from photoaging, and solar lentigines. It is known to be a very effective lightening agent, but several concerns have been raised about this widely used agent. The recent U.S. ban on over-the-counter skin lightening products containing hydroquinone has prompted further questioning of the safety of this widely used agent. While there have been prior informative, large-scale reviews on the safety of hydroquinone, new findings have since been reported. Here, we provide an updated review of studies published in the past 15 years on hydroquinone safety.