Can I take aspirin while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about aspirin.
In short
Pregnancy: If you take low-dose aspirin for blood clots, let your doctor know if you're pregnant or become pregnant. If your doctor recommends it, you can usually carry on taking it until week 20 of pregnancy, and sometimes beyond.
Breastfeeding: If you're breastfeeding, ask your doctor before you take low-dose aspirin for blood clots.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- If you take low-dose aspirin for blood clots, let your doctor know if you're pregnant or become pregnant.
- If your doctor recommends it, you can usually carry on taking it until week 20 of pregnancy, and sometimes beyond.
- To help prevent pre-eclampsia, your doctor may suggest starting low-dose aspirin from 12 weeks of pregnancy.
- Higher-dose aspirin for pain relief is not recommended at any point in pregnancy.
- If you're pregnant, paracetamol is usually the best painkiller to take.
Breastfeeding
- Your doctor may recommend it if the benefits are greater than the risks to your baby.
- Higher-dose aspirin for pain is not usually recommended during breastfeeding, as there's a risk of side effects in your baby.
- If you're breastfeeding, paracetamol is usually the best painkiller to take.
When to get help
- If you've been advised to take aspirin while breastfeeding and anything about your baby worries you, talk to a healthcare professional or call NHS 111 (in the UK).
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
Aspirin in pregnancy
The NHS says
If you take low-dose aspirin for blood clots, let your doctor know if you're pregnant or become pregnant. If your doctor recommends it, you can usually carry on taking it until week 20 of pregnancy, and sometimes beyond.
To help prevent pre-eclampsia, your doctor may suggest starting low-dose aspirin from 12 weeks of pregnancy.
Higher-dose aspirin for pain relief is not recommended at any point in pregnancy. If you're pregnant, paracetamol is usually the best painkiller to take.
In our words, from the NHS page Aspirin (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 Facts label says
If pregnant or breast-feeding, ask a health professional before use. It is especially important not to use aspirin at during the last 3 month of pregnancy unless definitely directed to do so by a doctor because it may cause problems in the unborn child or complications during delivery.
Drug Facts label: Low Dose Aspirin (oral), Strategic Sourcing Services LLC. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
More on aspirin in pregnancy: Bumps (Best Use of Medicines in Pregnancy) leaflet, Bumps (Best Use of Medicines in Pregnancy) leaflet (external site).
Aspirin while breastfeeding
The NHS says
If you're breastfeeding, ask your doctor before you take low-dose aspirin for blood clots. Your doctor may recommend it if the benefits are greater than the risks to your baby.
Higher-dose aspirin for pain is not usually recommended during breastfeeding, as there's a risk of side effects in your baby. If you're breastfeeding, paracetamol is usually the best painkiller to take.
If you've been advised to take aspirin while breastfeeding and anything about your baby worries you, talk to a healthcare professional or call NHS 111 (in the UK).
In our words, from the NHS page Aspirin (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
After aspirin ingestion, salicylic acid is excreted into breastmilk, with higher doses resulting in disproportionately higher milk levels. Long-term, high-dose maternal aspirin ingestion probably caused metabolic acidosis in one breastfed infant. Reye's syndrome is associated with aspirin administration to infants with viral infections, but the risk of Reye's syndrome from salicylate in breastmilk is unknown. An alternate drug is preferred over continuous high-dose, aspirin therapy. With low-dose aspirin (75 to 325 mg daily), no aspirin is excreted into breastmilk and salicylate levels are low. If a nursing mother uses aspirin, monitor the infant for bruising and bleeding.
“Summary of Use during Lactation”, LactMed record “Aspirin” (LM332), quoted verbatim. Everything LactMed reports about Aspirin while breastfeeding.
Other names
Sources
- NHS, Aspirin (nhs.uk), page last reviewed 3 July 2026. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- US drug label: Low Dose Aspirin (oral), Strategic Sourcing Services LLC, human otc drug, label effective 9 September 2026, set ID 7ce4807e-7bd5-41f1-a9c7-1f3af6acdc09. 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 “Aspirin” (LM332), 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.
- Bumps (Best Use of Medicines in Pregnancy), UK Teratology Information Service: Bumps (Best Use of Medicines in Pregnancy) leaflet. Linked, not reproduced.
- Bumps (Best Use of Medicines in Pregnancy), UK Teratology Information Service: Bumps (Best Use of Medicines in Pregnancy) leaflet. Linked, not reproduced.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.