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Key takeaways
Hydralazine is an antihypertensive therapy used for the management of hypertension.
It is generally considered to be safe during pregnancy, but is primarily used in hospital settings during acute situations that require rapid treatment, like severe preeclampsia.
If you have chronic high blood pressure before or during pregnancy, you will likely be prescribed an oral medication like labetalol or nifedipine rather than hydralazine.
Hydralazine is a prescription medication used to treat hypertension (high blood pressure). It is in a class of medications called vasodilators that lower blood pressure by relaxing the smooth muscles in the arteries, allowing blood to flow more easily. It was previously sold under the brand name Apresoline, but now only the generic is available.
High blood pressure during pregnancy can cause serious complications for mother and baby. Luckily, there are many preventive measures to avoid it, and medications that can help. Generally, hydralazine is considered safe to use in pregnancy, but it is not used in outpatient treatment unless other medications are ineffective. It is usually only used in emergency situations, such as preeclampsia.
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Can you take hydralazine while pregnant?
Hydralazine is used intravenously (IV) to treat two types of emergency high blood pressure during pregnancy:
- Hypertensive crisis: The American College of Obstetricians and Gynecologists (ACOG) and the American Heart Association (AHA) consider hydralazine a first-line treatment for the urgent treatment of extremely high blood pressure.
- Preeclampsia: Preeclampsia is a pregnancy condition in which blood pressure rapidly rises above 140/90 mmHg, and protein appears in the urine. It usually develops after 20 weeks of pregnancy and can pose serious risks for both the pregnant person and the baby. Hydralazine can quickly lower blood pressure.
Typically “the nurse will give a dose and if that doesn’t work in 15 to 20 minutes, they give the next higher dose and so on until they can get the blood pressure down to a safer range to prevent stroke, placental abruption, and other complications,” says Tricia Shimer, MD, an OB-GYN in Dallas, Texas.
The standard hydralazine dose in pregnancy is 5 mg via intravenous or intramuscular injection, and then 5-10 mg intravenously every 20-40 minutes.
Oral hydralazine is a second-line therapy for chronic hypertension (high blood pressure that is present before pregnancy or diagnosed before 20 weeks of pregnancy). In other words, it is only used in outpatient settings when other treatments have failed or are contraindicated.
The standard oral hydralazine dose in pregnancy is 10 mg to 50 mg four times a day.
What are the risks of taking hydralazine while pregnant?
Hydralazine is generally considered safe for pregnant women to take during the second and third trimesters (weeks 14 to 40 of pregnancy). There is no evidence that hydralazine is teratogenic in humans, meaning it does not cause developmental abnormalities in a human fetus. There is insufficient data to show complete safety for use in pregnant people, but it’s used when the benefits outweigh the potential risks.
The main risks of taking hydralazine during pregnancy are uncomfortable side effects. Maternal side effects of hydralazine include:
- Tachycardia (heart palpitations)
- Loss of appetite
- Nausea
- Diarrhea
- Headache
- Vomiting
- Chest pain
- Fluid retention
- Constipation
These side effects can happen in as many as 1 in 10 people who take the medication. The most serious side effects of hydralazine are tachycardia (an abnormally fast heart rate) and delayed hypotension (a dangerous drop in blood pressure that occurs after a medication is administered). Low blood pressure is dangerous because it reduces blood flow to vital organs.
Another rare complication of hydralazine is known as drug-induced lupus. This is much more common in people who take hydralazine for an extended period of time, which would not be the case for how hydralazine is currently clinically used (for acute situations on a short-term basis). There is a single case study in which a mother experienced this syndrome after taking hydralazine while pregnant.
Hydralazine does cross the placenta, according to the American Heart Association. Still, there is no evidence that hydralazine causes any developmental harm to babies. It can cause or contribute to other effects on the fetus, though, such as:
- Neonatal thrombocytopenia (a low platelet count that can increase the risk of bleeding)
- Fetal bradycardia (a slower-than-normal heart rate)
If a hospital provider suspects a baby was affected by hydralazine given during labor, the newborn would be evaluated by pediatrics, monitored closely, and treated if needed. It only passes into breastmilk in low amounts, so it’s generally considered safe while breastfeeding.
Other antihypertensive medications should not be taken at the same time as hydralazine. Drug interactions may also occur with monoamine oxidase inhibitors (MAOIs). Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen may reduce the effectiveness of hydralazine. This drug should be avoided in people who have coronary artery disease (CAD).
What can I take instead of hydralazine in pregnancy?
For chronic hypertension in pregnancy, the first-line antihypertensive treatments during pregnancy include oral meds such as:
Labetalol is the most common alternative to hydralazine, according to Dr. Shimer. It can be given intravenously to someone in a hospital for hypertensive emergencies, or taken orally to manage chronic hypertension during pregnancy.
A meta-analysis of 19 randomized controlled trials found that hydralazine and labetalol are similarly effective for acute blood pressure control, but that labetalol is associated with a lower risk of maternal hypotension, otherwise known as low blood pressure.
Natural remedies for hypertension during pregnancy
Hypertensive disorders of pregnancy, including chronic hypertension, gestational hypertension (or pregnancy-induced hypertension), and preeclampsia, are fairly common and affect approximately 5%-10% of pregnancies in the United States. These conditions have serious risks for both parents and fetuses, including preterm birth, fetal growth restriction, and an elevated risk of cardiovascular disease for mothers.
There are a few things you can do to manage high blood pressure during pregnancy without medication and during the perinatal period.
- Stay active! Some research indicates that regular exercise, such as aerobic exercise and strength training, can help lower blood pressure and support overall cardiovascular health during pregnancy.
- Try calming activities like meditation, deep breathing, and mindfulness. These stress reduction techniques may help you control your blood pressure better and feel better overall.
- Eat a balanced and nutrient-dense diet. A diet that is rich in whole grains, fruits, vegetables, proteins, and healthy fats can support heart health. Some pregnant women follow a modified version of the DASH diet (which stands for Dietary Approach to Stop Hypertension) during pregnancy. Only follow this diet if your healthcare provider recommends that you do so.
- Prioritize rest and hydration. According to one paper, poor sleep is associated with higher blood pressure in pregnancy. When you get enough sleep and drink enough fluid, your body works better overall. This supports blood sugar regulation and can help your cardiovascular system work well.
RELATED: How to take care of your heart during pregnancy and prevent heart disease
Keep in mind that any of these strategies may also be combined with medication to keep blood pressure manageable during pregnancy. “If you know you suffer from hypertension, make sure it is well controlled before you become pregnant, preferably by medications like labetalol and nifedipine that are safe in pregnancy,” advises Greg Marchand, MD, an OB-GYN and director of the Marchand Institute for Minimally Invasive Surgery in Mesa, Arizona.
Discuss your own situation, including your health history, concerns, goals, and how you are feeling emotionally with your healthcare provider. Inform them of any blood pressure management strategies you’re trying on your own to avoid any adverse effects when combined with medication.
- ACOG Committee Opinion No. 767: Emergent therapy for acute-onset, severe hypertension during pregnancy and the postpartum period, Obstetrics and Gynecology (2019)
- DASH (Dietary Approaches to Stop Hypertension) dietary pattern and maternal blood pressure in pregnancy, Journal of Human Nutrition and Dietetics (2020)
- Guidelines for the prevention of stroke in women: A statement for healthcare professionals from the American Heart Association/American Stroke Association, Stroke (2014)
- Hydralazine hydrochloride drug summary, Prescriber’s Digital Reference
- Hypertension in pregnancy, StatPearls (2022)
- Hypertension in pregnancy and postpartum: Current Standards and opportunities to improve care, Circulation (2025)
- Hypertension in pregnancy: Diagnosis, blood pressure goals, and pharmacotherapy: A scientific statement from the American Heart Association, Hypertension (2022)
- Lupus-like syndrome in a mother and newborn following administration of hydralazine; a case report, European Journal of Obstetrics, Gynecology, and Reproductive Biology (1989)
- Preeclampsia, The New England Journal of Medicine (2022)
- Poor sleep is associated with higher blood pressure and uterine artery pulsatility index in pregnancy: A prospective cohort study, BJOG: An International Journal of Obstetrics and Gynaecology (2021)
- The safety and effectiveness of mind body interventions for women with pregnancy induced hypertension and/or preeclampsia: A systematic review and meta-analysis, Complementary Therapies in Medicine (2020)