What is a fixed drug eruption?

Fixed drug eruption is a common type of drug eruption. It refers to a drug eruption that repeatedly occurs at a certain fixed site. The normal appearance of the rash is circular or oval purple-red erythema. Sometimes it is accompanied by blisters. Under normal circumstances, erythema or blisters easily occur on mucosal sites, such as the back of the hand, lips, vulva, etc., which are induced by antipyretic analgesics or antibiotics.