Nonpigmenting fixed drug eruption as a distinctive reaction pattern: examples caused by sensitivity to pseudoephedrine hydrochloride and tetrahydrozoline.

Nonpigmenting fixed drug eruption is a distinctive, clinically recognizable entity. Characteristically, the lesions are large, symmetrical, well-circumscribed tender erythematous plaques that suddenly appear and reappear in exactly the same sites. They fade without pigmentation or any other trace over a 2- to 3-week period. Management requires recognition and avoidance of the responsible drug. Acute attacks may call for short-term systemic steroid therapy. Three examples of this overlooked reaction pattern are presented. The first case was associated with Night-Time cold formula and was proved by specific component challenge to be due to d-pseudoephedrine hydrochloride. The second case was due to PediaCare 3 Children's Cough Syrup, also containing d-pseudoephedrine hydrochloride. The third case was due to Visine eye drops, which contain an imidazole derivative, tetrahydrozoline. There is a need to increase our awareness that fixed drug eruptions come in two very different clinical forms: the classic pigmenting asymmetrical form, and the nonpigmenting symmetrical erythematous plaque form, in both of which the patient will give a history of the eruption being recurrent in the same area.