Hydroquinone has long been used as the gold standard treatment for hyperpigmentation, yet despite its effectiveness, it has been associated with a severe adverse reaction known as exogenous ochronosis, where blue-black discoloration develops after long-term topical use. For decades, this condition was believed to occur through the same mechanism as endogenous ochronosis seen in alkaptonuria, a genetic disorder caused by mutations in homogentisate 1,2-dioxygenase (HGD) that lead to the accumulation of homogentisic acid.
This article was originally published on MedicalXpress.com
