Hydralazine‐Induced Fixed Drug Eruption

Abstract

A 62‐year‐old man had known hypertension for the past 6 years and had been under medical supervision for its control. Three years ago, his therapeutic regimen had included dihydralazine sulfate for the control of hypertension. He had responded favorably for the initial 3 months. Subsequently, he noticed an erythematous eruption confined to the nose and upper lip. It was preceded and accompanied by the burning sensation. The attending physician took cognizance of this episode and henceforth stopped dihydralazine sulfate. In a couple of weeks, symptoms and signs subsided, leaving behind pigmentation. The patient did not consume this particular drug for a couple of years. Two days prior to reporting to us, he had once again taken the same drug and had a flare‐up precisely confined to the earlier site.Examination of skin surface revealed a bluish‐black, edematous, irregular macule surrounded by an erythematous halo. It was confined to the bridge of the nose, extending to involve the right ala nasi, nasolabial fold, and adjoining part of the upper lip.Before embarking on a provocation test, a detailed drug history was elicited again. It was revealed that the patient had been taking propranolol and diazepam regularly. Dihydralazine sulfate was taken only as a complement to the regular treatment without any instruction from the attending physician, who was surprised this time by the exacerbation of the lesion. This prompted us to identify dihydralazine sulfate as the offending drug. Accordingly, the provocation with this drug was initiated with 12.5 mg orally, and the dose was increased to 37.5 mg on the third day. With the latter dose, 2 hours after the administration of drug, the patient experienced burning, erythema, and edema in the lesion, and an erythematous halo appeared around the lesion, corresponding to the previous site. The other drugs did not evoke any positive response.