Date: May 2022, Version 3

What is it?

Allopurinol is taken in combination with other medicines to treat inflammatory bowel disease. It is also used to help prevent rejection of a transplanted organ and to treat gout, kidney stones, and high levels of uric acid in the blood that can occur due to chemotherapy.


What are the benefits of taking allopurinol in pregnancy?

Allopurinol is sometimes used during pregnancy to help control inflammatory bowel disease, which is very important both for the woman’s wellbeing and to prevent certain pregnancy complications. It is also vital for both mother and baby that a transplanted organ continues to function well during pregnancy, and that the symptoms of painful conditions such as gout and kidney stones are well-controlled.


What are the risks of using allopurinol in pregnancy?

Only a small number of pregnant women taking allopurinol have been studied. The majority of the available information does not raise concern that its use causes problems. However, two babies exposed in the womb to allopurinol were born with similar, unusual birth defects. Ongoing research is therefore required to rule out that, in rare cases, allopurinol use can cause problems.


Are there any alternatives to using allopurinol in pregnancy?

Possibly. Other medicines are available to treat the illnesses that allopurinol is used for. However, if allopurinol was working well before pregnancy, a woman may be advised by her doctor to continue taking it. This will benefit both her and her baby by ensuring that her condition remains well-controlled.

Women who accidentally conceive while taking allopurinol should arrange to see their doctor or specialist to ensure that allopurinol is still the best treatment and to make sure the dose is correct.

No treatment

What if I prefer not to take medicines during pregnancy?

It is very important that inflammatory bowel disease is controlled, and that organ rejection continues to be prevented during pregnancy. Your doctor will only prescribe medicines when absolutely necessary and will be happy to talk to you about any concerns that you might have.

Will I or my baby need any extra monitoring?

As part of routine antenatal care, most women will be offered a very detailed scan at around 20 weeks of pregnancy to check the baby’s development. No additional monitoring is required due to taking allopurinol in pregnancy, although women with inflammatory bowel disease and organ transplants are likely to be offered additional monitoring of their own and their baby’s wellbeing.

Are there any risks to my baby if the father has used allopurinol?

There is no evidence that allopurinol used by the father can harm the baby through effects on the sperm..

Who can I talk to if I have questions?

If you have any questions about the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information from

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.