Date: April 2022, Version 1

What are they?

Diuretics (sometimes called ‘water tablets’) increase urine production and help to get rid of excess fluid. They are used in the treatment of heart failure, high blood pressure and some kidney conditions.

Diuretics commonly used in the UK include amiloride, chlorothiazide, hydrochlorothiazide, furosemide and spironolactone.


What are the benefits of using a diuretic in pregnancy?

Diuretics can be used in pregnancy but are rarely needed. When they are needed, it is to prevent serious complications from the build-up of excess fluid.


What are the risks of using a diuretic in pregnancy?

There is not much information on diuretics in pregnancy because hardly any pregnant women need to take them. However, there are a few issues that need to be considered:

Diuretics may reduce blood flow to the placenta. However, many of the medical conditions that you need diuretics for will also do this. Your baby will be monitored with extra growth scans.

Use of spironolactone specifically can potentially reduce testosterone levels in the baby. There are concerns that use in pregnancy could affect genital development in male babies. This has been shown in animal studies. There is a single human case report of a male baby with malformed genitals following spironolactone exposure, but also several case reports of male babies with normal genitals.

Use of a diuretic in pregnancy will only be recommended if the benefits of treating a potentially serious condition outweigh the possible risks.


Are there any alternatives to taking a diuretic in pregnancy?

Possibly. Women taking a diuretic to treat high blood pressure will usually be offered a different medicine that is known to be safe during pregnancy.

However, pregnant women with heart failure may be advised to continue taking a diuretic, as this can get worse during pregnancy and other drugs are unlikely to be as effective.

Swapping to a diuretic in pregnancy may be advised for women who are taking drugs called ACE-inhibitors and angiotensin receptor blockers, because these are dangerous for the baby if used in later pregnancy.

Women with conditions that affect the kidneys may also be advised to continue taking a diuretic to remain well.

If you are taking a diuretic and planning a pregnancy, speak to your doctor or specialist to make sure that this is right for you. Please do not make any changes to your medication unless your doctor has recommended this.

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What if I prefer not to take medicines in pregnancy?

It is important to take any medicines prescribed for high blood pressure, heart problems, or conditions affecting kidney function, as these can be serious for both mother and baby. A doctor will only prescribe medicines when necessary and will be happy to discuss any concerns.

Will I or my baby need extra monitoring?

As part of routine antenatal care, most women will be offered a detailed scan at around 20 weeks of pregnancy to check the baby’s development.

Women with high blood pressure, heart problems, or conditions affecting kidney function will be more closely monitored with additional growth scans during pregnancy to make sure that they remain well throughout and that their baby is growing as expected.

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

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

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.