Sirolimus

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Date: March 2025, Version 3.0

Quick read

Sirolimus can be used in pregnancy if recommended by a specialist.

What is it?

Sirolimus (Rapamune®, Hyftor®) lowers the immune response. It is most commonly used after a kidney transplant to prevent rejection. Sirolimus is also used to treat a rare and potentially serious lung disease called sporadic lymphangioleiomyomatosis.

Benefits

What are the benefits of taking sirolimus in pregnancy?

Sirolimus reduces the chance of organ rejection in people with a kidney transplant. It can also slow the progression of sporadic lymphangioleiomyomatosis. Both of these can be life-threatening and can lead to pregnancy complications.

Risks

Are there any risks of taking sirolimus during pregnancy?

Very few pregnant women taking sirolimus have been studied, and while no obvious problems have been noted, more women need to be studied to rule out any ill-effects.

Alternatives

Are there any alternatives to taking sirolimus?

Possibly. If you are taking sirolimus and planning a pregnancy or find out you are pregnant, you should speak to your doctor to see if you need to switch to a different medicine. For some women, continuing sirolimus in pregnancy may be necessary to prevent the rejection of a transplanted organ or to control sporadic lymphangioleiomyomatosis.

No treatment

What if I prefer not to take medicines during pregnancy?

It is very important to take any medicines prescribed to prevent organ rejection if you have received a transplant, and to reduce lung damage if you have sporadic lymphangioleiomyomatosis. Not having the correct treatment can be dangerous to you and can also lead to pregnancy complications. 

Your doctor will only prescribe medicines when necessary and will be happy to talk through any concerns. 

Do not stop sirolimus 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 as part of their routine antenatal care. This is normally carried out at around 20 weeks of pregnancy but may be offered slightly earlier in women taking sirolimus.

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

We do not expect any increased risk to your baby if the father takes sirolimus.

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 www.uktis.org.

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.

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