Minoxidil is an orally active vasodilator for treatment of severe hypertension. In combination with diuretics and beta-adrenergic blocking agents, it is effective treatment for more than 80% of patients whose blood pressure has been inadequately controlled with combinations of other been inadequately controlled with combinations of other antihypertensive drugs. Major adverse reactions include reflex activation of the adrenergic nervous system, renal sodium retention, and hypertrichosis. Despite the possibility of adverse reactions, minoxidil is indicated in patients whose blood pressure cannot be controlled with conventional therapy, in persons with major adverse reactions to other drugs, and in patients who are candidates for bilateral nephrectomy for control of hypertension.