(Date: September 2020. Version: 3)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by the UK Health Security Agency (UKHSA) on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What is it?

Sulfasalazine is a medicine that dampens the immune response. It used to treat ulcerative colitis, Crohn’s disease, and rheumatoid arthritis.

What are the benefits of taking sulfasalazine in pregnancy?

Sulfasalazine reduces ongoing tissue damage caused by ulcerative colitis, Crohn’s disease, and rheumatoid arthritis. It also controls unpleasant symptoms that can affect quality of life, and can help to prevent the pregnancy complications that have been associated with these illnesses.

Are there any risks of taking sulfasalazine during pregnancy?

There are no concerns that taking sulfasalazine in pregnancy causes problems in the baby and it is routinely prescribed for pregnant women with ulcerative colitis, Crohn’s disease, and rheumatoid arthritis.

Because sulfasalazine can potentially affect folic acid levels, women taking it while trying to conceive and during pregnancy should be prescribed a high dose folic acid supplement.

Are there any alternatives to taking sulfasalazine?

Possibly. Other medicines can be used to treat ulcerative colitis, Crohn’s disease, and rheumatoid arthritis. However, where a woman’s illness is well-controlled with sulfasalazine, staying on it may be the best option.

Ideally, women planning a pregnancy should speak to their specialist to determine whether sulfasalazine is still the most appropriate medicine for them. If you have an unplanned pregnancy while taking it, you should be reviewed at the earliest opportunity by your specialist. For many, ongoing use of sulfasalazine in pregnancy will be considered appropriate.

What if I prefer not to take medicines during pregnancy?

It is very important to take any medicines prescribed to treat ulcerative colitis, Crohn’s disease, and rheumatoid arthritis. Left untreated these can be serious and can also lead to pregnancy complications.

Your doctor will only prescribe medicines when absolutely necessary and will be happy to talk to you about any concerns that you might have.

Do not stop sulfasalazine without speaking to your midwife, GP, or specialist.

Will my baby need extra monitoring?

All pregnant women in the UK should be offered a detailed anomaly scan at around 20 weeks of pregnancy as part of their routine antenatal care. No extra monitoring for major birth defects is required following sulfasalazine use in pregnancy.

Are there any risks to my baby if the father has taken sulfasalazine?

We would not expect any increased risk to your baby if the father takes sulfasalazine.

Who can I talk to if I have questions?

If you have any questions regarding 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 offers all pregnant women, and women who have been pregnant in the past, the opportunity to create their own digitally secure ‘my bumps record’. You will be asked to enter information about your health, whether or not you take any medicines, and your pregnancy outcome. 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 to register.

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General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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