(Date: June 2014. Version: 2)

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 Public Health England 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.

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What is it?

Cetirizine (Benadryl one-a-day®, Zirtek®, Piriteze®, Pollenshield®) is an antihistamine and is used to treat allergic symptoms.

Is it safe to take cetirizine in pregnancy?

This leaflet summarises the scientific studies relating to the effects of cetirizine on a baby in the womb. It is advisable to consider this information before taking cetirizine if you are pregnant.

There is no evidence that cetirizine is harmful to a baby in the womb. However, because only a relatively small number of women have been studied it is not possible to say for certain that it does not affect a baby in some way.

When deciding whether or not to take cetirizine during pregnancy it is important to weigh up how necessary cetirizine is to your health against the possible risks to you or your baby, some of which will depend on how many weeks pregnant you are. Your doctor is the best person to help you decide what is right for you and your baby.

What if I have already taken cetirizine during pregnancy?

If you have taken or are taking any medicines it is always a good idea to let your doctor know that you are pregnant so that you can decide together whether you still need the medicines that you are on, and if so, to make sure that you are taking the lowest dose that works and only for as long as you need to.

Can taking cetirizine in pregnancy cause birth defects in the baby?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

There is no evidence that pregnant women taking cetirizine have a higher chance of having a baby with a birth defect from any of the five studies which have investigated this. However, because fewer than 500 pregnancies where the mother took cetirizine during the first trimester have been studied, further research is required to confirm these findings.

Can taking cetirizine in pregnancy cause miscarriage?

There is currently no evidence that taking cetirizine in early pregnancy increases the risk of miscarriage. Three studies have investigated this and none found an increased risk of miscarriage in women taking cetirizine compared either to women in the general population or to women who didn’t take cetirizine. However, because miscarriage rates have been studied in fewer than 250 women taking cetirizine during early pregnancy, more research into this subject is required.

Can taking cetirizine in pregnancy cause preterm birth, or my baby to be small at birth (low birth weight)?

No links between cetirizine use in pregnancy and pre-term birth (before 37 weeks of pregnancy) or low birth weight (<2500g) were found in either of the two studies that investigated this. Additionally, a large study of women taking any type of antihistamine (not just cetirizine) did not show that taking antihistamines during the first trimester made pre-term delivery or low birth weight more likely.

Can taking cetirizine in pregnancy cause stillbirth?

No link between cetirizine use in pregnancy and stillbirth has been shown. However, stillbirth rates have been investigated in fewer than 200 pregnant women taking cetirizine, and so more research is required.

Can taking cetirizine in pregnancy cause learning and behavioural problems in the child?

A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.

There is no known link between taking cetirizine in pregnancy and learning or behavioural problems (such as ADHD or autism spectrum disorder) in the child later on in life. There are, however, no scientific studies that have specifically investigated a link with these problems.

Will my baby need extra monitoring?

Most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects as part of their routine antenatal care. Taking cetirizine in pregnancy would not normally require extra monitoring of your baby. 

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

We would not expect any increased risk to your baby if the father took cetirizine 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 www.uktis.org.  

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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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