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What is hydralazine?

Hydralazine (also called Apresoline®) is an antihypertensive (blood pressure lowering medicine). It relaxes the blood vessels and lowers blood pressure. High blood pressure levels can damage kidneys, and may lead to stroke or heart failure. Hydralazine is available as 10 mg, 25 mg, and 50 mg tablets taken by mouth. It is also available as a clear liquid given by vein (IV).

Possible side effects of hydralazine

  • Low blood pressure (especially with the IV form)
  • Retaining sodium and water
  • Increased heart rate
  • Sudden weight gain
  • Loss of appetite
  • Short of breath
  • Swollen lymph nodes
  • Unusual weak or tired feeling
  • Headache
  • Nausea, vomiting
  • Diarrhea
  • Constipation
  • Nasal congestion
  • Low blood counts with an increased risk of bleeding, infection, and fatigue

Call the doctor right away if you have any of the following side effects:

  • Feeling dizzy and lightheaded or fainting spells
  • Swollen legs or ankles
  • Fast or irregular heartbeat, chest pain, palpitations
  • Skin rash, redness, blisters, or itching
  • Cold, tingling, or numb hands or feet
  • Joint pain, rash, fever, chills, or weakness and fatigue that will not go away (a lupus-like syndrome)

These are the most common side effects, but there may be others. Please report all side effects to the doctor or nurse.

In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 901-595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

Special instructions for hydralazine

  • Store the tablets at room temperature in a dry place.
  • Take hydralazine with food. Food increases the amount of drug that gets in your body. If you cannot take this with food every time, then always take it without food. It is important to take this medicine the same way and at the same time each day, so your blood pressure is controlled with the same amount of medicine each day.
  • This medicine may cause you to feel dizzy and lightheaded. Do not operate heavy equipment or drive a motor vehicle until you see how this medicine will affect you. To avoid feeling dizzy or having fainting spells do not sit up or stand up too quickly.
  • You or your nurse should check your blood pressure and heart rate regularly while you are taking hydralazine. Your doctor will tell you what to do if your blood pressure level is low or high. Your dose of hydralazine may change based on your blood pressure level. If your blood pressure is above _____________ or below__________, call your doctor right away. If your heart rate is _____________, call your doctor right away.
  • Hydralazine may affect the way some medicines work. Some medicines may also affect the way hydralazine works. These medicines include:
    • Other blood pressure medicines
    • Medicines for colds and coughs
    • Ibuprofen and other anti-inflammatory medicines
    • Medicines for depression
    • Female hormones (including birth control medicines)
    • Diuretics
    • Alcohol
  • Always tell your doctor if you are taking any of these medicines, or if you start taking any new medicine while you are taking hydralazine.
  • If you have a sudden onset of severe diarrhea or vomiting or if you sweat a lot, tell your doctor right away. This loss of body fluid may decrease your blood pressure.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).