Date: January 2023, Version 3

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Pyridostigmine can be used in pregnancy if needed to treat myasthenia gravis.

What is it?

Pyridostigmine (Mestinon®) is used to treat myasthenia gravis.


What are the benefits of taking pyridostigmine in pregnancy?

Pyridostigmine can improve muscle weakness caused by myasthenia gravis. This can help a woman remain well and able to carry out daily activities during pregnancy and while looking after her baby.


Are there any risks of taking pyridostigmine during pregnancy?

The available information suggests that using pyridostigmine in pregnancy does not affect the baby’s development; however, this ideally needs confirming with ongoing studies.


Are there any alternatives to taking pyridostigmine?

Possibly. Medicines that work by dampening the immune response can also be used to treat myasthenia gravis, so switching may be an option. However, if myasthenia gravis is well-controlled with pyridostigmine, it may be better to stay on it rather than try something new and risk a relapse.

Ideally, a woman planning a pregnancy should speak to her GP or specialist to determine whether pyridostigmine is still the best option. Similarly, women who have an unplanned pregnancy while taking pyridostigmine should be reviewed at the earliest opportunity by their GP or specialist.

No treatment

What if I prefer not to take medicines during pregnancy?

If myasthenia gravis causes problems with health and wellbeing, it is important that symptoms are well-controlled during pregnancy.

A medicine will only be prescribed during pregnancy if it is absolutely necessary, and a doctor or specialist will be happy to discuss the benefits and any risks.

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. Because this scan is so thorough, extra monitoring for birth defects is not usually required following pyridostigmine use in pregnancy.

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

We would not expect any increased risk to the baby if the father took pyridostigmine before or around the time you became pregnant.

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 (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.