Final answer:
A fixed drug eruption is an allergic skin reaction that occurs at the same site each time a specific drug is taken. It presents as a localized area of redness and inflammation, which may leave behind hyperpigmentation. Management typically involves stopping the drug and symptomatic treatment.
Step-by-step explanation:
A fixed drug eruption is a type of allergic reaction to a medication. It presents as a localized area of skin inflammation and discoloration that occurs at the same site each time the offending drug is taken. Typically, a fixed drug eruption begins as a red, itchy, or burning patch of skin, which then evolves into a well-demarcated, round or oval patch. After the drug is discontinued, the lesion usually heals with residual hyperpigmentation. If the drug is taken again, the same spot will often react. Common drugs that may cause these reactions include certain antibiotics, anti-inflammatory drugs, and anticonvulsants, though many others can also be responsible.
Diagnosis often involves taking a patient history to identify medication exposure, and may occasionally require skin biopsy or patch testing. Treatment usually involves cessation of the offending drug and managing symptoms with topical steroids or oral antihistamines, as necessary. It is crucial for patients to be aware of which medication caused their reaction to prevent recurrence.