Can I take glyceryl trinitrate (GTN) while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about glyceryl trinitrate (GTN).
In short
Pregnancy: Using glyceryl trinitrate (GTN) in pregnancy is not harmful. However, you won't usually need GTN while you're pregnant.
Breastfeeding: You can take or use glyceryl trinitrate (GTN) while breastfeeding if your doctor, health visitor or midwife tells you your baby is healthy.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- Using glyceryl trinitrate (GTN) in pregnancy is not harmful.
- However, you won't usually need GTN while you're pregnant.
- If you take GTN for angina, you should have a review with a pregnancy specialist (obstetrician) and a heart specialist (cardiologist).
- Until that review has happened, you can keep taking GTN.
- If you use GTN for anal fissures, speak to your doctor, who may suggest another medicine.
Breastfeeding
- Information about GTN rectal ointment and breastfeeding is limited, but it's not thought to give babies side effects.
- Wash your hands well after putting on the ointment and before you pick up your baby.
- There is no information on GTN tablets, sprays or patches during breastfeeding.
- The amount of GTN that reaches breast milk is not known, but it's probably very small and too low to cause side effects.
- As soon as you can, get in touch with your health visitor, midwife, doctor or pharmacist if anything worries you, including if your baby is feeding less well than normal, seems unusually sleepy or pale, or has a red face (flushing) straight after a breastfeed.
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
Glyceryl trinitrate (GTN) in pregnancy
The NHS says
Using glyceryl trinitrate (GTN) in pregnancy is not harmful. However, you won't usually need GTN while you're pregnant.
If you take GTN for angina, you should have a review with a pregnancy specialist (obstetrician) and a heart specialist (cardiologist). Until that review has happened, you can keep taking GTN.
If you use GTN for anal fissures, speak to your doctor, who may suggest another medicine.
In our words, from the NHS page Glyceryl trinitrate (GTN) (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: Pregnancy Category C: Animal teratology studies have not been conducted with nitroglycerin injection. Teratology studies in rats and rabbits, however, were conducted with topically applied nitroglycerin ointment at doses up to 80 mg/kg/day and 240 mg/kg/day, respectively. No toxic effects on dams or fetuses were seen at any dose tested. There are no adequate and well-controlled studies in pregnant women. Nitroglycerin should be given to a pregnant woman only if clearly needed.
Prescribing label, section “Pregnancy”: Nitroglycerin (intravenous), REMEDYREPACK INC. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
This quote is from the intravenous formulation label.
Glyceryl trinitrate (GTN) while breastfeeding
The NHS says
You can take or use glyceryl trinitrate (GTN) while breastfeeding if your doctor, health visitor or midwife tells you your baby is healthy.
Information about GTN rectal ointment and breastfeeding is limited, but it's not thought to give babies side effects. Wash your hands well after putting on the ointment and before you pick up your baby.
There is no information on GTN tablets, sprays or patches during breastfeeding. The amount of GTN that reaches breast milk is not known, but it's probably very small and too low to cause side effects.
As soon as you can, get in touch with your health visitor, midwife, doctor or pharmacist if anything worries you, including if your baby is feeding less well than normal, seems unusually sleepy or pale, or has a red face (flushing) straight after a breastfeed.
In our words, from the NHS page Glyceryl trinitrate (GTN) (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
LactMed says
Topical use of nitroglycerin for anal fissures by nursing mothers appears to have no adverse effects on their breastfed infants. Topical use on the nipples has been used for alleviation of Raynaud phenomenon of the nipples, but only after cessation of breastfeeding.[1] Nitroglycerin should not be used topically on the nipples during breastfeeding. Sublingual and intravenous nitroglycerin have not been studied during breastfeeding. Observe infants for flushing and discomfort after breastfeeding.
“Summary of Use during Lactation”, LactMed record “Nitroglycerin” (LM626), quoted verbatim. Everything LactMed reports about Nitroglycerin while breastfeeding.
The US prescribing label says
Nursing Mothers: It is not known whether nitroglycerin is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when nitroglycerin is administered to a nursing woman.
Prescribing label, section “Nursing Mothers”: Nitroglycerin (intravenous), REMEDYREPACK INC. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
This quote is from the intravenous formulation label.
Other names
UK brand names (per the NHS): Rectogesic, Minitran, Glytrin.
US name: nitroglycerin.
Sources
- NHS, Glyceryl trinitrate (GTN) (nhs.uk), page last reviewed 12 April 2023. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- US drug label: Nitroglycerin (intravenous), REMEDYREPACK INC., human prescription drug, label effective 1 September 2026, set ID b8af0974-33ea-4dd5-9ff7-3b61272aeb25. DailyMed (National Library of Medicine). Public domain; quoted verbatim.
- Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Nitroglycerin” (LM626), bulk release of 22 September 2026. LactMed on NCBI Bookshelf. Public domain; quoted verbatim. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.