Hydralazine | Side Effects, Dosage, Uses & More

Generic Name:

hydralazine, Oral tablet

All Brands

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Highlights for hydralazine

Oral tablet
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Hydralazine is an oral and injectable drug that’s used to treat high blood pressure. It’s used alone or in combination with other blood pressure-lowering drugs.

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Use this drug with caution if you have heart problems. Hydralazine may cause a heart attack, especially if you already have heart issues.

3

Common side effects include headache, loss of appetite, nausea, vomiting, diarrhea, fast heart rate, and chest pain.

4

Don’t stop taking hydralazine suddenly. Doing so may lead to uncontrolled high blood pressure. It can raise your risk for heart problems, such as chest pain or heart attack. If you need to stop taking this drug, your doctor will slowly lower your dose over two weeks. 

5

You may need to buy your own blood pressure monitoring machine to check your blood pressure at home. You should keep a log with the date, time of day, and your blood pressure readings. Bring this diary with you to your doctor appointments.

IMPORTANT INFORMATION

Lupus symptoms

Hydralazine may cause symptoms that can feel like lupus. Symptoms include:

  • joint pain and stiffness
  • a rash on your face
  • fever
  • tiredness
  • loss of appetite
  • nausea
  • weight loss
  • chest pain
  • kidney problems with symptoms such as:
    • pink or dark-colored urine
    • high blood pressure
    • swelling in your face, hands, and feet

Risk of nerve damage

Hydralazine may cause the following symptoms of nerve damage:

  • numbness or tingling in your hands and feet
  • prickling or itching of your skin

Tell your doctor if you have these side effects. They may suggest that you take vitamin B6 (pyridoxine) to help decrease these symptoms.

Heart problems

Use this drug with caution if you have heart problems. Hydralazine may cause a heart attack, especially if you already have heart issues. Tell your doctor about your heart condition.

Drug features

Hydralazine is a prescription drug. It is available in these forms: oral tablet and by injection, which is only given by a healthcare provider.

Hydralazine is available as a generic drug. Generic drugs usually cost less. In some cases they may not be available in every strength or form as the brand. Talk to your healthcare provider to see if the generic will work for you.

Hydralazine may be taken as part of a combination therapy with other blood pressure-lowering medicines.

Why it's used

Hydralazine is used to treat high blood pressure. It’s used alone or in combination with other blood pressure-lowering medicines.

How it works

Hydralazine belongs to a class of drugs called peripheral vasodilators.

More Details

How it works

Hydralazine belongs to a class of drugs called peripheral vasodilators. A class of drugs refers to medications that work similarly. They have a similar chemical structure and are often used to treat similar conditions.

It isn’t fully understood how hydralazine works. It’s thought that the drug acts on the blood vessels directly and relaxes them. This results in lower blood pressure levels.

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hydralazine Side Effects

Oral tablet

Most Common Side Effects

The most common side effects that occur with hydralazine include:

  • headache

  • loss of appetite (anorexia)

  • nausea

  • vomiting

  • diarrhea

  • fast heart rate

  • chest pain

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life-threatening or if you think you’re experiencing a medical emergency, call 9-1-1.

  • severe constipation

  • heart-related symptoms, such as:

    • very low blood pressure (hypotension)
    • fast heart rate
    • dizziness or disorientation
    • swelling in your arms and legs
  • trouble breathing

  • nerve problems. Symptoms include:

    • numbness
    • tingling
    • prickling or itching of your skin
  • depression or anxiety. Symptoms include:

    • feeling down or not like yourself
    • changes in appetite
    • feeling worried or on edge
    • not being interested in activities you normally enjoy
  • trouble urinating

  • allergic reaction. Symptoms include:

    • skin rash
    • itching skin
    • redness to your skin
    • fever
    • chills
    • pain in your joints
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Hydralazine does not cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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hydralazine May Interact with Other Medications

Oral tablet

Hydralazine can interact with other medications, herbs, or vitamins you might be taking. That’s why your doctor should manage all of your medications carefully. If you’re curious about how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interactions.

Food interactions

Taking hydralazine with food can increase the level of the drug in your bloodstream. This may raise your chance for side effects such as severe drop in blood pressure or dizziness.

Alcohol interaction

The use of drinks that contain alcohol can increase the blood pressure-lowering side effects from hydralazine. If you drink alcohol, talk to your doctor.

Medications that might interact with this drug

Depression medications

Some depression medicines increase the effects of hydralazine. This may raise your risk of side effects, such as very low blood pressure (hypotension).

These drugs include:

  • monoamine oxidase inhibitors (MAOIs), such as:
    • isocarboxazid
    • phenelzine sulfate
    • tranylcypromine sulfate
    • selegiline

Diazoxide injection

This drug can cause a severe drop in blood pressure when used with hydralazine.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

People with heart problems

Use this drug with caution if you have heart problems. Hydralazine may cause a heart attack, especially if you already have heart issues. Tell your doctor about your heart condition.

Pregnant women

Hydralazine is a category C pregnancy drug. That means two things:

  1. Research in animals has shown adverse effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Tell your doctor if you’re pregnant or plan to become pregnant. Hydralazine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Women who are breast-feeding

Small amounts of hydralazine may pass into breast milk, However, this drug doesn’t typically cause side effects in a child who is breastfed.

Talk to your doctor if you breastfeed your baby.

For seniors

Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dose or a different schedule.

For children

This medicine hasn’t been studied in children younger than 18 years, but it’s been used in children.

Allergies

Hydralazine can cause a severe allergic reaction. Symptoms include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

Don’t take this drug again if you’ve ever had an allergic reaction to it before. Taking it again could be fatal (cause death).

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How to Take hydralazine (Dosage)

Oral tablet

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

High blood pressure (hypertension)
Form: Oral tablet
Strengths: 10 mg, 25 mg, 50 mg, and 100 mg
Adult dosage (ages 18–64 years)
  • starting dose: 10 mg taken by mouth 4 times per day for 2–4 days
  • dose adjustments: Your doctor may slowly increase your dose up to 50 mg taken 4 times per day.
Child dosage (ages 1–17 years)
  • This medicine hasn’t been studied in clinical trials for children younger than 18 years, but it has been used in children.
  • starting dose: 0.75 mg per kg of body weight per day taken by mouth in four divided doses
  • dose adjustments: Your doctor may slowly increase your dose over 3–4 weeks.
  • maximum dose: 7.5 mg per kg of body weight or 200 mg per day
Senior dosage (ages 65 years and older)

There are no specific recommendations for senior dosing. Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dose or a different schedule.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Hydralazine comes with serious risks if you don't take it as prescribed.

If you don't take it at all

If you don’t take hydralazine as prescribed by your doctor, your blood pressure may stay high (hypertension). This increases your chance of having a stroke and heart attack.

If you stop taking it suddenly

Don’t stop taking hydralazine suddenly. Doing so may lead to uncontrolled high blood pressure. This can put you at a higher risk for heart problems, such as chest pain or a heart attack. If you need to stop taking this drug, your doctor will slowly decrease your dose over two weeks.

If you don’t take it on schedule

Not taking this drug on schedule can put you at a higher risk for heart problems, such as chest pain or heart attack.

What to do if you miss a dose

If you forget to take your dose, take it as soon as you remember. If it’s just a few hours until the time for your next dose, then wait and only take one dose at that time. Never try to catch up by taking two doses at once. This could cause toxic side effects.

If you take too much

You may have severe side effects, such as:

  • very low blood pressure (hypotension)
  • irregular heart rate
  • headache
  • redness and warmth to your skin (flushing)
  • heart attack
  • shock

If you think that you’ve taken too much hydralazine, call your doctor or go to the emergency room right away.

How to tell this drug is working

You may be able to tell if this drug is working if your blood pressure goes down. Your doctor will also monitor your blood pressure to make sure that this medication is working for you.

Hydralazine is a long-term drug treatment.

Hydralazine can be taken with or without food

You should try to stay consistent in how you take this drug. If you usually take it with food, always take it with food and vice versa. This will help reduce your risk of side effects.

Taking hydralazine with food can increase the level of the drug in your bloodstream. This may raise your chance for side effects such as excessive drop in blood pressure or dizziness.

This drug must be stored at the right temperature

  • Store hydralazine at room temperature between 68°F (20°C) and 77°F (25°C).
  • Don’t freeze this medication.
  • Keep it away from high temperature.
  • Keep your drugs away from areas where they could get wet, such as bathrooms. Store this drug away from moisture and damp locations.

Travel

When traveling with your medication:

  • Always carry it with you or in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff your pharmacy’s label to clearly identify the medication. Keep the original prescription label with you when traveling.
  • Don’t put this medicine in the car, especially when the temperature is hot or freezing.

Self-management

You may need to check your blood pressure and heart rate at home. You should keep a log with the date, time of day, and your blood pressure readings. Bring this diary with you to your doctor appointments.

You may also need to buy your own blood pressure monitoring machine. These are available for purchase at most pharmacies.

Clinical monitoring

Before starting and during your treatment with hydralazine, your doctor may check your:

  • blood pressure
  • blood tests to check for side effects from the drug

Hidden costs

You may need to purchase a blood pressure monitor to check your blood pressure at home.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

What does the pill look like?

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How Much Does hydralazine Cost?

Oral tablet

We've partnered with GoodRx so you can compare prices, find discounts and save up to 80% on your next prescription. Check out the low coupon prices below — no insurance required.

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Lowest price for hydralazine

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Target (CVS) $8.66
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These prices represent the lowest priced national pharmacies for hydralazine on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for hydralazine on GoodRx. They may be lower than your insurance.

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Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on September 2, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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