What are the fastest-acting antihypertensive medications, listed from quickest to longest onset of action?

From the Guidelines

The fastest-acting antihypertensive medications are Nitroprusside, Esmolol, Metoprolol, Phentolamine, and Nitroglycerine, with onset of action ranging from immediate to 2 minutes.

Fastest-Acting Antihypertensive Medications

• Nitroprusside: immediate onset of action, used for acute cardiogenic pulmonary edema and acute aortic disease 1
• Esmolol: 1-2 minutes onset of action, used for acute aortic disease and hypertensive emergencies 1
• Metoprolol: 1-2 minutes onset of action, used for hypertensive emergencies 1
• Phentolamine: 1-2 minutes onset of action, used for hypertensive emergencies induced by catecholamine excess 1
• Nitroglycerine: 1-5 minutes onset of action, used for acute coronary events and acute cardiogenic pulmonary edema 1

Other Antihypertensive Medications

• Labetalol: 5-10 minutes onset of action, used for malignant hypertension, hypertensive encephalopathy, and acute ischemic stroke 1
• Nicardipine: 5-15 minutes onset of action, used for hypertensive emergencies and acute ischemic stroke 1
• Clevidipine: 2-3 minutes onset of action, used for hypertensive emergencies 1
• Fenoldopam: 5-15 minutes onset of action, used for hypertensive emergencies 1
• Urapidil: 3-5 minutes onset of action, used for hypertensive emergencies and acute hemorrhagic stroke 1
• Enalaprilat: 5-15 minutes onset of action, used for hypertensive emergencies 1
• Clonidine: 30 minutes onset of action, used for hypertensive emergencies, but not recommended as first-line treatment due to its slow onset of action 1

From the Research

Fastest-Acting Antihypertensive Medications

The following list outlines the fastest-acting antihypertensive medications, from quickest to longest onset of action, based on available evidence:

• Nifedipine and captopril: onset of action within 0.5-1 hour 2
• Clonidine and labetalol: maximal blood pressure lowering effects at 2-4 hours 2 Other antihypertensive medications, such as diuretics, angiotensin II receptor blockers, and beta-blockers, may have a slower onset of action, but are still effective in lowering blood pressure 3, 4, 5, 6

Onset of Action for Specific Medications

The onset of action for specific antihypertensive medications is as follows:

• Nifedipine: within 0.5-1 hour 2
• Captopril: within 0.5-1 hour 2
• Clonidine: 2-4 hours 2
• Labetalol: 2-4 hours 2
• Losartan: does not persist throughout 24 hours 6
• Telmisartan: persists over 24 hours when administered once daily in the morning 6