Hydralazine Oral Tablet

Hydralazine is a prescription drug. It’s available as an oral tablet and an injection. The injection is only given by a healthcare provider.

Hydralazine is only available as a generic drug. Generic drugs usually cost less than brand-name versions.

Why it's used

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

How it works

Hydralazine belongs to a class of drugs called peripheral vasodilators. A class of drugs is a group of medications that work in a similar way. These drugs 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.

Hydralazine oral tablet 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.

Examples of medications that can interact with hydralazine are listed below.

Depression medications

Monoamine oxidase inhibitors (MAOIs) can increase the effects of hydralazine. This raises your risk of side effects, such as very low blood pressure (hypotension). These drugs include:

• 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.

This drug comes with several warnings.

Allergies

Hydralazine can cause a severe allergic reaction. Symptoms can 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).

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.

Warnings for certain groups

For 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. Be sure to tell your doctor about your heart condition before taking hydralazine.

For 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.

For women who are breastfeeding: Small amounts of hydralazine may pass into breast milk. However, this drug doesn’t typically cause side effects in a child who is breastfed. If you breastfeed your baby, talk to your doctor about the safety of this drug.

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 drug hasn’t been studied in children younger than 18 years, but it has been used in children.

Keep these considerations in mind if your doctor prescribes hydralazine for you.

General

• Take this drug at the time(s) recommended by your doctor.
• You can cut or crush the tablet.
• 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 an excessive drop in blood pressure or dizziness.

Storage

• Store hydralazine at room temperature between 68°F and 77°F (20°C and 25°C).
• Don’t freeze this medication.
• Don’t store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

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