Specific site involvement in fixed drug eruption.

A total of 105 patients with established fixed drug eruption (FDE) by oral provocation were evaluated with regard to a drug-related site involvement. Cotrimoxazole was the leading causative agent (63.8%), followed by naproxen sodium (23.8%), dipyrone (5.7%), oxicams (4.8%) and other rare causes (1.9%). Cotrimoxazole most frequently induced lesions on genital mucosa; naproxen and oxicams on lips; and dipyrone on trunk and extremities. Isolated FDE on male genitalia (n = 16) was exclusively because of cotrimoxazole. A highly significant association could be established between naproxen and FDE on lips (chi-square = 28.3; corrected P =.000002). As this study represents the largest series of patients with naproxen-induced FDE, we would suggest that naproxen should be considered as an important potential cause of FDE on lips.