What are common physical findings of fixed drug eruptions (FDE)?

Updated: Oct 09, 2020
  • Author: David F Butler, MD; Chief Editor: Dirk M Elston, MD  more...
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Initially, a single lesion or a few lesions develop, but, with reexposure, additional lesions occur. The vast majority of patients present with 1-30 lesions, ranging in size of 0.5-5 cm, but reports of lesions greater than 10 cm have been published. Lesions may be generalized. The most common reported site is the lips, and these may be seen in up to half of all cases. [1]

Medications may also follow a site-specific eruption pattern. For example, trimethoprim-sulfamethoxazole (Bactrim) has been shown to favor the genital region (especially in males) and naproxen and the oxicams involve the lips. [2]

Resting/inactive lesions tend to appear as round or oval, gray, hyperpigmented macules.

Upon reexposure, the resting hyperpigmented macules activate, developing a violaceous center encircled by concentric rings of erythema. Re-administration of the medication poses the risk of increased pigmentation, size, and number of lesions.

Individuals with darker pigmentation may develop postinflammatory hypopigmented macules once the lesions have resolved. [13]

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