Can I take isosorbide mononitrate and isosorbide dinitrate while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about isosorbide mononitrate and isosorbide dinitrate.
In short
Pregnancy: Isosorbide mononitrate and isosorbide dinitrate can be taken while you're pregnant.
Breastfeeding: Isosorbide mononitrate or isosorbide dinitrate may be an option while breastfeeding, provided your doctor, midwife or health visitor is happy that your baby is healthy. Your doctor or pharmacist can help you make the decision, so speak to them first.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- However, if you're pregnant or trying for a baby, you should see a heart specialist (cardiologist) and a pregnancy specialist (obstetrician) as soon as possible, so they can review your heart health and your medicine.
- Keep taking your medicine until that review has happened.
Breastfeeding
- Isosorbide mononitrate or isosorbide dinitrate may be an option while breastfeeding, provided your doctor, midwife or health visitor is happy that your baby is healthy.
- Your doctor or pharmacist can help you make the decision, so speak to them first.
- Nobody knows exactly how much isosorbide mononitrate or isosorbide dinitrate reaches breast milk, but the levels are likely to be low.
- It's unlikely to cause side effects in your baby.
- Carrying on with your medicine is important to keep you well, and breastfeeding also has benefits for both you and your baby.
- If you have any worries about your baby, speak to your health visitor, midwife, pharmacist or doctor.
- This includes if your baby is not feeding as well as they usually do or not gaining weight as you'd expect, is unusually sleepy, or is irritable.
Talk to your doctor or pharmacist
This page is educational, not advice for your own situation. Talk to your doctor, midwife or pharmacist before you start, stop or change any medicine in pregnancy or while breastfeeding.
The details: what each source says
Isosorbide mononitrate and isosorbide dinitrate in pregnancy
The NHS says
Isosorbide mononitrate and isosorbide dinitrate can be taken while you're pregnant.
However, if you're pregnant or trying for a baby, you should see a heart specialist (cardiologist) and a pregnancy specialist (obstetrician) as soon as possible, so they can review your heart health and your medicine.
Keep taking your medicine until that review has happened.
In our words, from the NHS page Isosorbide mononitrate and isosorbide dinitrate (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
The US drug label says
Pregnancy Teratogenic Effects Reproduction studies performed in rats and rabbits at doses of up to 540 and 810 mg/kg/day, respectively, have revealed no evidence of harm to the fetus due to isosorbide mononitrate. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, isosorbide mononitrate should be used during pregnancy only if clearly needed. Nonteratogenic Effects Birth weights, neonatal survival and development, and incidence of stillbirths were adversely affected when pregnant rats were administered oral doses of 540 (but not 270) mg isosorbide mononitrate/kg/day during late gestation and lactation. This dose was associated with decreased maternal body weight gain and decreased maternal motor activity.
Prescribing label, section “Pregnancy” (opening excerpt): Isosorbide Mononitrate (oral), Coupler LLC. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Isosorbide mononitrate and isosorbide dinitrate while breastfeeding
The NHS says
Isosorbide mononitrate or isosorbide dinitrate may be an option while breastfeeding, provided your doctor, midwife or health visitor is happy that your baby is healthy. Your doctor or pharmacist can help you make the decision, so speak to them first.
Nobody knows exactly how much isosorbide mononitrate or isosorbide dinitrate reaches breast milk, but the levels are likely to be low. It's unlikely to cause side effects in your baby.
Carrying on with your medicine is important to keep you well, and breastfeeding also has benefits for both you and your baby.
If you have any worries about your baby, speak to your health visitor, midwife, pharmacist or doctor. This includes if your baby is not feeding as well as they usually do or not gaining weight as you'd expect, is unusually sleepy, or is irritable.
In our words, from the NHS page Isosorbide mononitrate and isosorbide dinitrate (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
The US prescribing label says
Nursing Mothers It is not known whether isosorbide mononitrate is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when isosorbide mononitrate is administered to a nursing woman.
Prescribing label, section “Nursing Mothers”: Isosorbide Mononitrate (oral), Coupler LLC. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Other names
UK brand names (per the NHS): Chemydur XL, Isotard, Monomil XL, Elantan LA.
US name: isosorbide mononitrate.
Sources
- NHS, Isosorbide mononitrate and isosorbide dinitrate (nhs.uk), page last reviewed 27 August 2024. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- US drug label: Isosorbide Mononitrate (oral), Coupler LLC, human prescription drug, label effective 6 July 2026, set ID 55f240e1-3056-38cc-e063-6294a90a814e. DailyMed (National Library of Medicine). Public domain; quoted verbatim.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.