Promethazine

(Date: December 2019. Version: 3)

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?

Promethazine (Phenergan®) is a sedating (drowsy) antihistamine that is used to treat allergies, nausea and vomiting (including in pregnancy), and for short-term treatment of some sleep problems.

When deciding whether to use promethazine during pregnancy it is important to weigh up the potential benefits to your health and wellbeing against any possible risks to you or your baby, some of which may depend on how many weeks pregnant you are. Your doctor or specialist will be able to help you make decisions about your treatment.

What if I have already taken promethazine during pregnancy?

If are taking any medicines while pregnant you can discuss this with your doctor. You can then decide together whether ongoing treatment is appropriate, and, if so, your doctor will ensure that you are taking the most effective dose.

Can taking promethazine 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.

Over 5,000 women taking promethazine in early pregnancy have been studied as it is used quite commonly to treat pregnancy sickness. These studies do not raise concern of a link with birth defects in the baby.

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

No studies have specifically assessed the likelihood of these pregnancy outcomes in women taking promethazine in pregnancy. Although ongoing research is ideally required to rule out any problems, promethazine is quite widely used in pregnancy and so any common adverse effects would likely have been identified.

Can taking promethazine 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.

No studies have assessed the learning and behaviour of children exposed in the womb to promethazine.

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 promethazine in pregnancy would not normally require extra monitoring of your baby. 

Exposure in the womb to promethazine in the two weeks prior to delivery may lead to temporary changes to the baby’s nervous system that can affect their behaviour for a few days after birth, The baby may cry more, be jittery, respond differently to stimuli, and be harder to settle. Women who have taken promethazine around the time of delivery may therefore be advised to have their baby in a unit with facilities to monitor the baby and offer any required treatment.

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

We would not expect any increased risk to your baby if the father took promethazine 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.

   

www.medicinesinpregnancy.org

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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