Hypertensive emergencies require blood pressure reduction within 60 minutes to halt target organ damage. Definitive treatment of eclampsia is delivery. Temporizing measures include magnesium sulfate, hydralazine or labetalol. In a patient with aortic dissection and hypertension, labetalol, a combined alpha- and beta-blocker, is given with nitroprusside to reduce the blood pressure and aortic pressure wave. Nitroglycerin for hypertension associated with pulmonary edema lowers blood pressure and preload while dilating coronary arteries. Nitroprusside has been described as having a coronary steal phenomenon, which makes it less attractive in this setting. Nitroprusside however is the drug of choice for hypertensive encephalopathy. Pheochromocytoma requires both alpha and beta blockade to lower blood pressure, and propranolol would result in unopposed alpha stimulation, paradoxically increasing the blood pressure.