Erythema multiforme and urticaria. Eruptions induced by chemically related ophthalmic anticholinergic agents.

Erythema multiforme developed in an 80-year-old man following the use of scopolamine hydrobromide ophthalmic drops. The erythema multiforme cleared when the medication was discontinued and recurred on challenge. Later, he was given tropicamide, an anticholinergic ophthalmic preparation that, like scopolamine, has a tropic acid residue. Within 15 minutes an immediate hypersensitivity reaction with generalized urticaria developed in the patient.