Hydralazine (By mouth)


Hydralazine Hydrochloride (hye-DRAL-a-zeen hye-droe-KLOR-ide)

Treats high blood pressure.

Brand Name(s)


When This Medicine Should Not Be Used

How to Use This Medicine


  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Some foods and medicines can affect how hydralazine works. Tell your doctor if you are using diazoxide or an MAO inhibitor.

Warnings While Using This Medicine

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, heart or blood vessel disease, heart rhythm problems, lupus, or if you had a heart attack or stroke.
  • This medicine may cause the following problems:
    • Lupus-like syndrome
    • Changes in heart rhythm
    • Nerve problems
  • This medicine may lower your blood pressure too much and cause you to feel dizzy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Change in how much or how often you urinate
  • Chest pain that may spread to your arms, jaw, back, or neck, trouble breathing, unusual sweating, faintness
  • Fast, pounding, or uneven heartbeat
  • Fever, chills, cough, sore throat, and body aches
  • Lightheadedness, dizziness, or fainting
  • Numbness, tingling, or burning pain in your hands, arms, legs, or feet
  • Unusual bleeding, bruising, or weakness

If you notice these less serious side effects, talk with your doctor:

  • Diarrhea, nausea, vomiting, loss of appetite
  • Headache
  • Stuffy nose or watery eyes

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 7/4/2015

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