months to resolve Although usually solitary, multiple or very large lesions may form in fixed drug eruption following repeated exposure to the triggering medication The lesions can be pruritic, burning, or asymptomatic Initially, lesions appear within weeks of starting a medication, but with repeated exposure, onset can occur in minutes to hours Sulfonamides, particularly trimethoprim-sulfamethoxazole, are the most common causes of fixed drug eruption in children ( Fig 68.7 ), though NSAIDs and tetracycline are also frequent causes Some foods and food additives have also been reported to cause fixed drug reactions Fixed drug eruption can often be confused for arthropod bites, urticaria, or EM The history of recurrence in the exact same location with prominent postinflammatory hyperpigmentation is more suggestive of a fixed drug eruption rather than arthropod bites Similarly, fixed drug eruption is typically not as pruritic as arthropod bites As noted above, urticaria is transient, so individual lesions resolve within 24 hours, with any residual pigmentation or purpura resolving within days rather than the months that fixed drug eruption hyperpigmentation may last As compared to EM, the lesions of fixed drug eruption are larger and fewer and occur in a different distribution Stopping and avoiding the causative medication allows for resolution of the fixed drug eruption and prevents recurrence A fixed drug eruption does not progress to more severe drug eruptions, like DHR or Stevens–Johnson syndrome (SJS) If needed, a topical steroid can treat pruritus