Treatment of head lice during pregnancy

(Date: February 2018. 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 the UK Health Security Agency (UKHSA) 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.

Quick read

Head lice can be treated in pregnancy using wet combing with conditioner and a fine-tooth comb, or using an insecticide treatment that kills the lice.

What are head lice?

Head lice are tiny insects that live in head hair and cause itching. Nits are the eggs that are sometimes visible in the hair.

Head lice are easily spread and are common in children. You can look for head lice by combing hair with a special fine-toothed comb that traps the lice. If one member of your household has head lice, you should check everyone else in the house and treat all affected individuals at the same time.

How do I treat head lice during pregnancy?

Wet combing

Current UK guidelines recommend that pregnant women who need to treat their own or their child’s head lice can use ‘wet combing’. This avoids the use of any chemicals. Wet combing involves thorough, frequent combing of wet hair with a special comb and conditioner. Further information on wet combing can be found on the NHS A-Z leaflet Head lice and nits


If wet combing is not effective or is not preferred, insecticides (products that kill insects) can be used.

There are two types of insecticides:

1) Physical insecticides which coat the head lice and kill them by blocking their breathing and/or water balance.

2) Chemical insecticides which kill head lice by poisoning them.

Physical insecticides

Dimethicone (Hedrin® products, Lyclear® Spray, Linicin® Lotion, NYDA® Spray), cyclomethicone (Full Marks® Solution), and isopropyl myristate and isopropyl alcohol (Vamousse®) kill head lice by blocking their breathing and/or water balance. Physical insecticides are harmless to humans and also do not enter the bloodstream in amounts that could cause problems for the baby.

Chemical insecticides

Malathion (Derbac® M Liquid, Prioderm® Lotion) is a chemical insecticide that kills head lice by poisoning them.

No studies have been carried out to look at whether using malathion to treat head lice during pregnancy affects the baby. However, if malathion is used as recommended by the manufacturer, any risk is expected to be very low as it will only enter the bloodstream in tiny amounts. As a precaution, it is recommended to first try the other methods to clear head lice in pregnancy and only use malathion if these have not worked.

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.

Using treatments for head lice during pregnancy is not expected to cause any problems that would require extra monitoring of the baby.

Are there any risks to my baby if the father has used head lice treatments?

There is currently no evidence that head lice treatments used by the father can harm the baby through effects on the sperm.

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 allows women with a current or previous pregnancy to create a digitally secure ‘my bumps record’. You will be asked to enter information about your health, whether or not you take any medicines, and your pregnancy outcome. 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 to register.

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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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