Hyperemesis gravidarum

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Date: January 2025, Version 1.0

Quick read

Hyperemesis gravidarum is very severe pregnancy sickness. There are a number of medicines that can be used safely to improve the symptoms of hyperemesis gravidarum.

What is hyperemesis gravidarum?

Up to three in every 100 pregnant women get a very severe type of pregnancy sickness called hyperemesis gravidarum. Affected women have very bad nausea (feeling sick) and/or vomiting (being sick). This means they cannot eat or drink normally and can’t carry out their daily activities. Constantly feeling and/or being sick and being unable to live a normal life can also cause problems with mental health. 

What medicines are used for hyperemesis gravidarum?

Your doctor might offer you an antihistamine first. Antihistamines that can help with sickness include cyclizine, prochlorperazine, chlorpromazine, and promethazine. A drug called Xonvea® is also available, which combines an antihistamine (doxylamine) with vitamin B6.

If an antihistamine doesn’t help within two days, your doctor can talk to you about using other medicines. These include ondansetron, metoclopramide, and domperidone. Some women may need to use more than one medicine at the same time to feel better.

Benefits

What are the benefits of using a medicine to treat hyperemesis gravidarum?

Using an anti-sickness medicine in pregnancy can improve your symptoms. Some women will feel well enough to carry on with their normal daily activities.

Treatment of hyperemesis gravidarum can help to prevent dehydration (where you don’t have enough water in your body) caused by being sick and not drinking properly. Effective sickness treatment can help you avoid hospital treatment for dehydration.

Treating sickness and nausea can allow you to eat. This can help your unborn baby to grow and reduce the chance of them having a low birth weight.

Risks

Are there any risks of using a medicine to treat hyperemesis gravidarum?

Overall, these medicines are considered to be safe for your baby.

Although ondansetron has been linked to a small increase in the risk of cleft palate and some heart defects in babies who were exposed in the womb, it is clear that this is very rare. It is important to balance this small risk against the benefits to you, your unborn baby, and your wider family of your pregnancy sickness being well-treated. For more details, see the Bump leaflet on Ondansetron.

Alternatives

Are there any alternatives to using a medicine to treat hyperemesis gravidarum?

Not usually. Because hyperemesis gravidarum is so severe, it generally needs treatment with a medicine.

No treatment

What if I prefer not to use a medicine to treat hyperemesis gravidarum?

If you cannot eat or drink normally, you are vomiting up medicines that you need to take, and/or you cannot carry out your normal activities, there is no need to suffer. It is important to get the correct anti-sickness treatment to keep you as well as possible.

Will my baby need extra monitoring?

As part of their routine antenatal care, most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects. Using anti-sickness treatments does not mean that you need any extra monitoring during pregnancy.

If you have hyperemesis gravidarum that carries on after week 20, you might be offered extra scans in later pregnancy to keep an eye on your baby’s growth. Your health and wellbeing will also be regularly monitored. 

Who can I talk to if I have questions?

If you have any questions relating to 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.

The charity Pregnancy Sickness Support provides resources, information and advice for women experiencing hyperemesis gravidarum.

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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