Hydralazine is used with or without other medications to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Hydralazine is called a vasodilator. It works by relaxing blood vessels so blood can flow through the body more easily.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used for heart failure.

Take this medication by mouth with or without food as directed by your doctor, usually 2 to 4 times daily. The dosage is based on your medical condition and response to treatment. Your doctor may start you at a low dose and gradually increase your dose. Follow your doctor's instructions carefully.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick. It may take up to several weeks before you get the full benefit of this drug.

Do not stop taking this medication without consulting your doctor. Some conditions may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased.

Tell your doctor if your condition does not get better or if it gets worse (your blood pressure readings remain high or increase).

Headache, pounding/fast heartbeat, loss of appetite, nausea, vomiting, diarrhea, or dizziness may occur as your body adjusts to the medication. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

To reduce the risk of dizziness, get up slowly when rising from a sitting or lying position.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication may rarely cause nerve problems. Tell your doctor promptly if you experience numbness or tingling. Your doctor may recommend a vitamin B6 supplement (pyridoxine).

Tell your doctor right away if you have any serious side effects, including:

• severe tiredness
• aching/swollen joints
• rash on nose and cheeks
• swollen glands
• signs of kidney problems (such as change in the amount of urine, bloody/pink urine)
• signs of infection (such as sore throat that doesn't go away, fever, chills)
• easy bruising/bleeding

Get medical help right away if you have any very serious side effects, including:

• chest/jaw/left arm pain

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking hydralazine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• heart problems (such as coronary artery disease, recent heart attack, rheumatic heart disease of the mitral valve)
• blood vessel problems
• previous stroke
• kidney problems

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this medication, especially dizziness, which can increase the risk of falls.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk, but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are:

• MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine)

Some products have ingredients that could raise your heart rate or blood pressure or worsen your heart failure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen).

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: severe dizziness, fainting, flushing, chest/jaw/left arm pain, irregular heartbeat.

Do not share this medication with others.

Lifestyle changes such as stress reduction programs, exercise, and dietary changes may help this medication work better. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.

Lab and/or medical tests (such as complete blood count) may be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

Have your blood pressure checked regularly while taking this medication. Learn how to monitor your own blood pressure, and share the readings with your doctor.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.