Localized Morbilliform Drug Eruption Following Sildenafil Exposure: A Case Report

Sildenafil is a commonly used medication for the treatment of erectile dysfunction and is generally well-tolerated. Cutaneous adverse drug reactions associated with sildenafil are uncommon and have been described in various clinical forms. We report a case of a 34-year-old man with no significant medical history who developed an asymptomatic, localized morbilliform eruption four days after taking a single 100 mg dose of sildenafil, representing his first reported exposure. The eruption consisted of erythematous macules and papules confined to the back, without mucosal involvement, facial edema, vesiculation, bullae formation, purpura, desquamation, or systemic symptoms. Complete blood count and serum biochemical investigations were unremarkable, with no eosinophilia or evidence of hepatic, renal, or hematologic abnormalities. No other medications, supplements, recent infectious illness, or other apparent triggers were identified. Based on the clinical presentation and temporal relationship, a sildenafil-associated morbilliform drug eruption was considered. The Naranjo Adverse Drug Reaction Probability Scale yielded a score of 6, indicating a probable adverse drug reaction. The patient was treated conservatively with antihistamines, and the eruption resolved spontaneously without corticosteroid therapy or other specific interventions. This case highlights an uncommon localized morbilliform eruption following sildenafil exposure and emphasizes the importance of recognizing this potential adverse reaction.