What are the contraindications for hydralazine?

Hydralazine Contraindications

Hydralazine is absolutely contraindicated in patients with coronary artery disease and mitral valvular rheumatic heart disease, and should not be used in pregnancy (ACE inhibitor class effect). 1

Absolute Contraindications

Based on FDA labeling and major guidelines, hydralazine must not be used in:

• Coronary artery disease - Hydralazine causes myocardial stimulation that can precipitate anginal attacks, ECG changes of myocardial ischemia, and has been implicated in producing myocardial infarction 1

• Mitral valvular rheumatic heart disease - The hyperdynamic circulation caused by hydralazine may increase pulmonary artery pressure in patients with mitral valvular disease 1

• Hypersensitivity to hydralazine 1

Specific Clinical Situations Where Hydralazine Should Not Be Used

Acute Settings (IV Hydralazine)

According to the 2017 ACC/AHA Hypertension Guidelines 2, 3, 2:

• Acute myocardial infarction - Contraindicated due to reflex tachycardia and increased myocardial oxygen demand
• Bilateral renal artery stenosis - Can precipitate acute renal failure
• Pregnancy - Listed as contraindicated (though this appears to be an error in the guideline tables, as hydralazine is actually used in pregnancy; see nuance below)

Relative Contraindications and High-Risk Situations

Use with extreme caution or avoid in:

• Cerebrovascular accidents - Should be used cautiously 1
• Advanced renal damage - Use with caution as with any antihypertensive 1
• Suspected coronary artery disease - Must be used with caution due to myocardial stimulation 1
• Pulmonary vascular obstructive disease secondary to congenital heart disease - Can increase pulmonary arterial pressure and worsen hemodynamics 4

Important Clinical Caveats

The Pregnancy Paradox

The 2017 ACC/AHA guidelines list pregnancy as a contraindication for IV enalaprilat but appear to incorrectly include this notation near hydralazine 2. In reality, hydralazine is one of the preferred agents for hypertensive emergencies in pregnancy 5. The 2025 AHA/ACC guidelines clarify that hydralazine (along with labetalol and nifedipine) is appropriate for acute blood pressure management in severe preeclampsia 5.

Hypertensive Emergency Context

The 2017 ACC/AHA guidelines note that hydralazine's "unpredictability of response and prolonged duration of action do not make hydralazine a desirable first-line agent for acute treatment in most patients" 2, 3, 2. While not contraindicated, it should generally be avoided as first-line therapy in hypertensive emergencies except in pregnancy.

Drug-Induced Lupus Risk

While not an absolute contraindication, higher doses of hydralazine (>200 mg/day) are associated with drug-induced lupus-like syndrome 2, 6. Complete blood counts and antinuclear antibody titers should be monitored during prolonged therapy 1.

Drug Interactions

• MAO inhibitors - Should be used with caution when combined with hydralazine 1
• Diazoxide - Profound hypotensive episodes may occur when used concomitantly 1

Practical Algorithm for Deciding on Hydralazine Use

Do NOT use hydralazine if:

1. Known coronary artery disease → Choose alternative agent
2. Mitral valvular rheumatic heart disease → Choose alternative agent
3. Acute MI in progress → Choose beta-blocker or nitrate instead
4. Bilateral renal artery stenosis → Choose alternative agent
5. Pulmonary vascular disease from congenital heart disease → Risk of worsening pulmonary hypertension

Use with extreme caution if:

1. Suspected CAD → Monitor closely for angina/ischemia
2. Recent stroke → Consider alternative first
3. Advanced renal disease → Monitor renal function closely
4. Concurrent MAO inhibitor use → Consider alternative or close monitoring

Appropriate use:

1. Resistant hypertension in African Americans (with isosorbide dinitrate) 7
2. Heart failure with reduced ejection fraction in African Americans (with isosorbide dinitrate) 7, 8
3. Severe preeclampsia/eclampsia (IV formulation) 5
4. Alternative when ACE inhibitors/ARBs contraindicated in HFrEF 7