Oral mucosal lichenoid reaction to sulfamethoxazole.

A clinical case of oral mucosal lichenoid reaction to sulfamethoxazole in a dental patient with complicating medical conditions is described. Although the relationship between oral mucosal lichenoid reaction and sulfa drugs has not been documented previously, the patient's lichenoid reaction corresponded with sulfamethoxazole use, and improved when the drug was discontinued. Reactions of this type should be monitored so that treatment and preventive measures may be instituted.