Medicine & USMLE


Cardio Drugs - Blood Pressure
  1. ACE Inhibitors
  2. Angiotensin II Receptor Blockers (ARBs)
  3. Beta Blockers: Mechanisms and Clinical Uses
  4. Beta Blockers: Side Effects
  5. DHP Calcium Channel Blockers
  6. Hydralazine
  7. Aliskiren
  8. Nitroprusside
  9. Alpha-1 Blockers
  10. Clonidine


Hydralazine is a medication that is safe to use in pregnancy and is often used to treat patients with heart failure and hypertension. It does this by causing vasodilation, and it specifically vasodilates the arteries more than the veins. As a result, hydralazine decreases afterload on the heart.

Side effects of hydralazine include hypotension, dizziness, drug-induced lupus, and chest pain. Hydralazine can cause edema, especially in the lower legs and feet. It can also cause headache and reflex tachycardia.

Key Points

  • Hydralazine
    • Clinical Use
      • Treat hypertension
        • Safe to use in pregnancy
          • While lots of other antihypertensive medications are teratogenic, hydralazine is safe to use during pregnancy
        • Works quickly, so it can be used for hypertensive emergencies
      • Treat heart failure
        • When combined with isosorbide, hydralazine can be used to treat heart failure
    • Mechanism
      • Vasodilation
        • Affects arteries more than veins
        • The smooth muscle in the arteries relaxes, causing the blood vessel to widen
      • Reduces afterload
    • Side Effects
      • Hypotension
        • Do not give if patient has low blood pressure
      • Dizziness (Orthostatic Hypotension)
        • Sudden changes in movement can cause the blood pressure to drop, making the patient feel dizzy
        • Advise patients to change positions slowly to prevent dizziness
      • Reflex tachycardia
        • When the blood pressure lowers quickly, the body naturally reacts by increasing the heart rate
      • Chest pain (angina)
      • Drug-induced lupus
        • Lupus-like symptoms may appear, including muscle and joint pain, fever, and fatigue
      • Edema
        • Sodium and fluid retention leads to swelling in the extremities, especially the legs and ankles
      • Headache