Side effects from topical application of hydroquinone include mild burning, redness, stinging or dryness, according to WebMd. Hydroquinone is not proscribed for oral use and can cause poisoning if ingested. Hydroquinone is a topical medication commonly used to lighten skin discolorations, such as dark spots or freckles.Continue Reading
Topical gels and ointments containing hydroquinone are available over the counter in the United States in low concentration and with prescription for higher concentrations, medically used as a skin bleaching agent. The American Society for Dermatologic Surgery advocates its safety when used topically.
In 2006 the FDA responded to studies in which the drug was administered orally to rats, finding that it was debatable whether or not to rule it out as a carcinogenic agent. The FDA recommended hydroquinone for further testing to determine whether or not it should qualify as "GRASE" or Generally Recognized As Safe and Effective. As of 2015, it remains on the market as a topical medication in the meantime, and the ASDS states that there is no link between its topical use and cancer.
The concern over hydroquinone's potential carcinogenic properties lies when it is ingested, notes the ASDS. Ingestion of hydroquinone may cause poisoning or intoxication. Severe poisoning symptoms include dark urine, vomiting, abdominal pain, tachycardia, tremors, coma and potentially death. There is no known therapeutic value in ingesting hydroquinone.Learn more about Medications & Vitamins