Date: February 2019, Version 3

What is it?

Mefloquine is a medicine that is taken either on its own or more commonly in combination with another medicine to:
• prevent malaria infection (for example, before travelling to a part of the world where the chance of being infected with malaria is high) 
• treat a person who has been infected with malaria 

Malaria is a serious illness that is spread by mosquito bites and can result in death. Malaria infection in pregnancy can be dangerous to both mother and baby. Pregnant women are therefore advised to avoid travelling to areas where there is a risk of catching malaria. If you are pregnant or planning a pregnancy and cannot avoid travelling to a high risk malaria area, ask your doctor for advice as soon as possible. You may need to start taking an antimalarial medicine a few weeks before you travel. Your doctor is the best person to help you decide what is right for you and your baby.

Is it safe to take mefloquine in pregnancy?

If you are travelling to certain regions you may be advised to take mefloquine. This is because in some areas other anti-malarial medicines are ineffective. You should not avoid taking mefloquine just because you are pregnant. The risk of harm to you and your baby from malaria is far greater than any potential risk from taking mefloquine.

No antimalarial medicine is 100% effective and it is very important that you also reduce the chance of being bitten by using insect repellents, mosquito nets, and covering as much skin as possible with clothing, particularly between dawn and dusk. Please read our bumps leaflet on insect repellents for more information on which products are advised for use in pregnancy.

Can taking mefloquine in pregnancy cause miscarriage?

There is currently no evidence that mefloquine use in pregnancy causes miscarriage.

Eleven studies investigated the chance of miscarriage with mefloquine use. In nine of these studies no link with miscarriage was seen. One study looked at front-line soldiers who took mefloquine, however the miscarriage rate may be higher in this population due to factors other than medicine use. The other study showed a slight increase in miscarriage following use of mefloquine compared to other antimalarial drugs, but women taking mefloquine still had a similar chance of miscarriage as women in the background population.

Overall, the studies on the chance of miscarriage in women taking mefloquine during pregnancy are reassuring, but more information on pregnant women taking mefloquine is needed.

Can taking mefloquine in pregnancy cause my baby to be born with birth defects?

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

No studies suggest that women who take mefloquine in early pregnancy have a higher chance of having a baby with a birth defect.

Can taking mefloquine in pregnancy cause preterm birth?

Mefloquine use in pregnancy has not been shown to cause a baby to be born early in any of three studies. Malaria infection has been linked to preterm birth.

Can taking mefloquine in pregnancy cause my baby to be small at birth (low birth weight)?

No increased chance of low birth weight was seen in four out of the five studies of babies born to pregnant women taking mefloquine. Although one study did suggest a possible link with low birth weight, this study included pregnant women with malaria which is itself known to cause low birth weight in the baby.

Can taking mefloquine in pregnancy cause stillbirth?

No increased chance of stillbirth was seen in four out of the five studies of pregnant women taking mefloquine. Although one study did suggest a possible link, this study included women with malaria which is itself known to increase the chance of stillbirth.

Can taking mefloquine in pregnancy cause learning or 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. Because use of mefloquine has been linked to long-term neurological and mental health problems in some people, it has been questioned whether mefloquine might hypothetically affect the development of an unborn baby’s brain. It has also been suggested that malaria infection during pregnancy might affect a baby’s developing brain, but this too remains to be confirmed.

There is no evidence so far that mefloquine use in pregnancy causes learning or behavioural problems in the child. Four studies have all shown no difference in the age at which children who were exposed to mefloquine while in the womb reached key developmental milestones (such as sitting, walking and talking) compared to unexposed children.

Will my baby need extra monitoring during pregnancy?

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 and to check the baby’s growth.

Taking mefloquine during pregnancy is not expected to cause any problems that would require extra monitoring of your baby. However, if you have been infected with malaria during your pregnancy your doctor may wish to monitor your pregnancy more closely.

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

We would not expect any increased risk to your baby if the father took mefloquine before or around the time your baby was conceived.

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.