No, you should not take lisinopril while pregnant. The drug carries an FDA boxed warning for fetal toxicity, the strongest safety warning the agency issues. When pregnancy is detected, lisinopril should be stopped as soon as possible and replaced with a blood pressure medication that is safer during pregnancy.
Why Lisinopril Is Dangerous During Pregnancy
Lisinopril belongs to a class of blood pressure drugs called ACE inhibitors, which work by blocking a hormone system that regulates blood pressure and fluid balance. The problem is that the same system plays a critical role in fetal development, particularly in the kidneys. When lisinopril suppresses this system in a developing fetus, the fetal kidneys can’t function properly, which sets off a chain of complications.
The most immediate consequence is a drop in amniotic fluid, the protective liquid surrounding the baby. Because the fetus produces much of that fluid through urine output, damaged kidneys mean less fluid. Low amniotic fluid then leads to its own set of problems: underdeveloped lungs, limb contractures from compression, and skull bone abnormalities. In severe cases, the combination of kidney failure and these complications can be fatal.
These risks are most clearly established during the second and third trimesters. The specific conditions documented in exposed pregnancies include:
- Kidney damage: ranging from impaired function to irreversible renal failure
- Skull hypoplasia: incomplete development of the skull bones
- Lung hypoplasia: underdeveloped lungs from low amniotic fluid
- Growth restriction: the baby measuring smaller than expected
- Patent ductus arteriosus: a heart vessel that fails to close after birth as it normally would
Newborns who were exposed to ACE inhibitors in the womb also need close monitoring after delivery for low blood pressure, low urine output, and elevated potassium levels.
What About First Trimester Exposure
If you took lisinopril before realizing you were pregnant, the risk picture is more reassuring than many people expect. A large study of over 1.3 million pregnancies, published in Obstetrics & Gynecology, examined first-trimester ACE inhibitor exposure (lisinopril was the most commonly used, accounting for about 55% of exposures). The raw numbers initially looked concerning: 5.9% of exposed pregnancies had malformations compared to 3.3% of unexposed ones.
But when researchers accounted for the fact that these women also had high blood pressure, which itself raises the risk of birth defects, the difference disappeared. After adjusting for the underlying hypertension, first-trimester ACE inhibitor exposure showed no statistically significant increase in overall malformations, heart defects, or nervous system defects. The adjusted relative risk for overall malformations was 0.89, meaning exposed pregnancies actually had a slightly lower rate than other hypertensive pregnancies, though the difference wasn’t statistically meaningful.
This doesn’t mean first-trimester use is safe, but it does mean that brief early exposure before you knew you were pregnant is not a reason to panic. Your provider will likely recommend ultrasound screenings to check for skull bone development, kidney abnormalities, and amniotic fluid levels as your pregnancy progresses.
Safer Blood Pressure Options During Pregnancy
Managing high blood pressure during pregnancy is still important. Uncontrolled hypertension carries its own serious risks, including preeclampsia. The goal is switching to a medication with a better safety profile, not stopping treatment altogether.
The two most commonly recommended first-line options are labetalol (a type of beta-blocker) and methyldopa. Both have long track records of use in pregnancy. Labetalol is often preferred because it tends to be better tolerated. Long-acting nifedipine, a calcium channel blocker, is a common second-line choice. Your provider will select the best fit based on your blood pressure severity and how you respond to the medication.
If you’re planning a pregnancy and currently taking lisinopril, the ideal approach is to switch medications before conceiving. This avoids any early exposure during the critical first weeks of organ development, when you might not yet know you’re pregnant.
Lisinopril and Breastfeeding
Unlike pregnancy, lisinopril appears to be compatible with breastfeeding. Studies measuring the drug in breast milk found very low concentrations. At a standard 10 mg daily dose, the peak milk level was 0.63 micrograms per liter, translating to a relative infant dose of just 0.06%, a tiny fraction of what the mother takes. In a small group of breastfeeding women taking lisinopril at doses ranging from 5 to 20 mg daily, four of five reported no adverse effects in their infants at all. The amounts transferred through milk are considered too small to cause problems in a nursing baby.