Can I take allopurinol while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about allopurinol.
In short
Pregnancy: Allopurinol is not usually recommended if you're pregnant, because the evidence is not strong enough to say it's safe.
Breastfeeding: You can take allopurinol while breastfeeding if your doctor or health visitor tells you your baby is healthy.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- If you're planning to try for a baby, speak to a doctor.
- Other medicines may suit you better while you're pregnant.
Breastfeeding
- Little is known about allopurinol and breastfeeding, but it probably gets into breast milk in small amounts.
- Speak to your doctor, pharmacist, midwife or health visitor if your baby is feeding less well than normal, is vomiting (being sick), has diarrhoea or a rash, or if anything else about your baby worries you.
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
Allopurinol in pregnancy
The NHS says
Allopurinol is not usually recommended if you're pregnant, because the evidence is not strong enough to say it's safe.
If you're planning to try for a baby, speak to a doctor. Other medicines may suit you better while you're pregnant.
In our words, from the NHS page Allopurinol (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: Reproductive studies have been performed in rats and rabbits at doses up to twenty times the usual human dose (5 mg/kg per day), and it was concluded that there was no impaired fertility or harm to the fetus due to allopurinol. There is a published report of a study in pregnant mice given 50 or 100 mg/kg allopurinol intraperitoneally on gestation days 10 or 13. There were increased numbers of dead fetuses in dams given 100 mg/kg allopurinol but not in those given 50 mg/kg. There were increased numbers of external malformations in fetuses at both doses of allopurinol on gestation day 10 and increased numbers of skeletal malformations in fetuses at both doses on gestation day 13. It cannot be determined whether this represented a fetal effect or an effect secondary to maternal toxicity. There are, however, no adequate or well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
Prescribing label, section “Pregnancy” (opening excerpt): Allopurinol (oral), Redpharm Drug. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Allopurinol while breastfeeding
The NHS says
You can take allopurinol while breastfeeding if your doctor or health visitor tells you your baby is healthy.
Little is known about allopurinol and breastfeeding, but it probably gets into breast milk in small amounts.
Speak to your doctor, pharmacist, midwife or health visitor if your baby is feeding less well than normal, is vomiting (being sick), has diarrhoea or a rash, or if anything else about your baby worries you.
In our words, from the NHS page Allopurinol (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
Limited information indicates that a maternal dose of allopurinol of 300 mg daily provides near-therapeutic dose and plasma levels in an exclusively breastfed infant. The manufacturer recommends avoiding allopurinol during breastfeeding and for one week after the last dose. If the mother requires allopurinol, it is not a reason to discontinue breastfeeding, but exclusively breastfed infants should be monitored if this drug is used, including observation for allergic reactions (such as rash) and periodic CBC and differential blood counts.
“Summary of Use during Lactation”, LactMed record “Allopurinol” (LM334), quoted verbatim. Everything LactMed reports about Allopurinol while breastfeeding.
The US prescribing label says
Nursing Mothers Allopurinol and oxipurinol have been found in the milk of a mother who was receiving allopurinol tablets. Since the effect of allopurinol on the nursing infant is unknown, caution should be exercised when allopurinol tablets are administered to a nursing woman.
Prescribing label, section “Nursing Mothers”: Allopurinol (oral), Redpharm Drug. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Other names
UK brand names (per the NHS): Zyloric, Uricto.
Indian brands (per NPPA): Zyloric.
Sources
- NHS, Allopurinol (nhs.uk), page last reviewed 23 January 2023. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- US drug label: Allopurinol (oral), Redpharm Drug, human prescription drug, label effective 23 January 2025, set ID 0a22fa72-c363-4e96-e063-6394a90a48aa. 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 “Allopurinol” (LM334), 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.