Malathion liquid

You will need to use malathion liquid twice - two treatments seven days apart.

If you get any in your eye(s), rinse it out straightaway with plenty of water.

Type of medicine Insecticide
Used for Treatment of scabies, head lice, and pubic lice
Also called Derbac-M®
Available as Liquid for use on the skin

Malathion is an insecticide. It kills lice and scabies mites.

Lice are tiny insects that live on humans, usually in hair. They are passed on through close contact.

Scabies is an itchy skin disorder that leads to a rash. It is caused by the scabies mite. The mite lives on the skin and burrows into it. Scabies is contagious and spreads to others through close skin-to-skin contact.

Malathion liquid is available on prescription, or you can buy it without a prescription at pharmacies.

To make sure this is the right treatment for you, before you start using malathion liquid it is important that your doctor or pharmacist knows:

  • If any areas of your skin are sore or infected.
  • If you are pregnant or breast-feeding.
  • If it is for a child under 6 months old. This is because, in very young children, it should only be used on the advice of a doctor.
  • If you have ever had an allergic reaction to a medicine or skin product.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about how to apply malathion, and a full list of unwanted effects from using it. Two applications of treatment are needed, one week apart.
  • To treat head lice: apply the liquid to dry hair and rub it into your scalp. Let your hair dry naturally. Leave it on for 8-12 hours (or overnight) and then shampoo it out. Comb through your hair, using a 'nit comb', while it is still wet to remove the dead lice and eggs (nits). Repeat this process again seven days later.
  • To treat scabies: apply the liquid over your whole body including your face, neck, scalp and ears, but try to take care not to get any into your eyes. Remember to include awkward places such as your back, the soles of your feet, between your fingers and toes, under your fingernails, and your genitals. Also, pay special attention to the areas where mite burrows most commonly occur - the front of your wrists and elbows, beneath your breasts, your armpits, and around the nipples in women. The liquid should be applied when your skin is cool and dry, so if you have just had a bath or shower, wait for a little while to let your skin cool before you apply it. Let it dry naturally. Leave it on for 24 hours, and then wash it off. Each time you wash your hands using soap during this 24 hours, make sure you reapply the liquid to your hands afterwards. Repeat the treatment seven days later.
  • To treat pubic (crab) lice: apply the liquid over your whole body including your face, neck, scalp and ears, but try to take care not to get any into your eyes. Remember to include awkward places and pay particular attention to all hairy areas and your genitals. Let it dry naturally. Leave it on for twelve hours (or overnight) and then wash it off. Re-apply malathion in the same way, seven days after the first application. This will help to make sure that all the lice are killed.
  • Do not use malathion more often than is recommended on the label. If you feel the treatment has not been successful, make an appointment to see your doctor for further advice. An alternative preparation may be recommended for you.
  • If you are using malathion for head lice, it can help to comb your hair with a nit comb every four days. Comb through small sections of wet hair and remove any lice you find. It can take half an hour or so to do this over the whole scalp. Continue to do this twice a week until your hair is free from lice on three consecutive sessions.
  • If you have pubic lice, your recent close contacts and sexual partners should also be treated if they are infected. It is important to remember that lice may be present without other symptoms such as itching.

The following may also apply if you have scabies:

  • It is important that the whole family should be treated with malathion at the same time to prevent the mite transferring between your family.
  • If you have scabies, your sleeping/sexual partners and everyone living with you should also be treated, even if they have no symptoms. Close contacts may be infected but have no symptoms because it can take up to six weeks for symptoms to develop. Everyone who is treated, should be treated on the same day.
  • Children should stay off school until the first application of treatment for scabies has been completed.
  • You will still be itchy for a while after successful treatment. If the itching becomes troublesome to you, your doctor or pharmacist will be able to advise you regarding suitable products to ease this. Moisturising creams can provide temporary relief from itching.
  • It is normal for it to take up to 2-3 weeks (and sometimes up to six weeks) for the itch to go completely after scabies mites have been killed. You should, however, see a doctor if the itch persists for longer than 2-3 weeks after treatment. This is because sometimes the first insecticide does not work, and you may need to use a different one.
  • Some people may develop a secondary skin infection which may need antibiotic treatment. If you suspect this is the case for you, you should make an appointment to see your doctor.

Malathion occasionally causes skin irritation. This should soon pass, but if it is severe or becomes troublesome, stop using malathion and ask your doctor or pharmacist for advice.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

This preparation is for use on the skin only. If someone swallows some of this preparation, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • Manufacturer's PIL, Derbac M® Liquid; SSL International plc, The electronic Medicines Compendium. Dated December 2011.
  • British National Formulary; 63rd Edition (Mar 2012) British Medical Association and Royal Pharmaceutical Society of Great Britain, London
Original Author: Helen Allen Current Version: Peer Reviewer: Dr Hannah Gronow
Last Checked: 16/10/2012 Document ID: 3328  Version: 25 © EMIS

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.