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.

What are head lice?

Head lice are insects that live in head hair. Adult lice live for about 30 days by sucking blood from the scalp. They lay eggs which attach to the hair and take 7-10 days to hatch. Newly hatched lice start laying their own eggs after 6-10 days.

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 at the same time and treat all affected individuals until clear.

How do I treat head lice during pregnancy?

Wet Combing
Current UK guidelines recommend that pregnant women with head lice can use ‘wet combing’ to clear lice. This avoids the use of any chemicals. Wet combing involves thorough, frequent combing of wet hair with a special comb. Further information on wet combing can be found at NHS choices (

If wet combing is not considered an option or is not effective, insecticides (products that kill insects) can be applied to the hair and scalp to treat head lice. Insecticides should only be used where live lice have been found in the hair. Some insecticide treatments only kill adult lice and may therefore have to be repeated more than once to kill new lice which have hatched from eggs already in the hair.

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 myristrate and isopropyl alcohol (Vamousse®) kill head lice by blocking their breathing and/or water balance.  No studies have been carried out to examine whether use of these products during pregnancy is linked to problems in the unborn baby. However, similar substances are present in many day-to-day cosmetic items and are not known to be linked to any problems.

It is, however, advisable for pregnant women to seek advice from their healthcare provider before using these products and to follow the individual product guidelines.

Chemical Insecticides

Malathion (Derbac® M Liquid, Prioderm® Lotion) is a chemical insecticide that kills head lice by poisoning them. Malathion is also sprayed on crops to kill insect pests.

The manufacturers of malathion state that pregnant women should consult their doctor before use.

No studies have been carried out to look at whether using malathion to treat head lice during pregnancy is linked to an increased risk of poor pregnancy outcome. However, information from a small number of studies which looked at the pregnancy outcomes of women who had been exposed to malathion crop sprays (e.g. through working on farms) are generally reassuring. These studies do not suggest that women exposed to malathion are any more likely to miscarry, have a baby with a birth defect, a premature delivery (before 37 weeks of pregnancy), or a baby with a low birth weight (less than 2,500g). There is also no proof that being exposed to malathion when you are pregnant causes learning or behavioural problems in the child.

What if I have to treat my child’s head lice and I am pregnant?

If you do not require treatment for head lice yourself, but must apply insecticides to another family member, it is recommended that you follow the manufacturer’s instructions on how to use the product and take any suggested safety precautions. If you would prefer to avoid using a chemical product you may wish to first try wet combing to treat head lice, followed by dimethicone/cyclomethicone, with malathion as a last resort.

Will my baby need extra monitoring during pregnancy?

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

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

We would not expect any increased risk to your baby if the father used head lice treatments 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

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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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