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Malathion for Lice


Generic Name Brand Name
malathion (0.5%) Ovide

This prescription lotion must be applied to dry hair and left on for 8 to 12 hours before rinsing off. Do not use hair conditioner. Because this medicine contains alcohol, avoid sources of heat and open flame such as hair dryers, curling irons, fireplaces, and cigarettes until it has dried.

If lice are still present 7 to 9 days later, your doctor may suggest a second treatment.

How It Works

Malathion kills lice and their eggs (nits).

Why It Is Used

Malathion works very well against lice. It is less widely used than other lice medicines because treatment requires 8 to 12 hours and because the odor is bad.

Malathion is not recommended for use by women who are pregnant or breast-feeding or children younger than 2 years of age.

How Well It Works

Malathion works very well at killing lice after one treatment. It sometimes is used to treat lice that have become resistant to permethrin and pyrethrins.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you or your child has:

Call your doctor if your child has:

Side effects of this medicine include:

  • Skin irritation.
  • Scalp irritation.

It can cause severe respiratory problems if swallowed.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Malathion contains alcohol and is able to catch fire until it dries. Do not expose it to open flame, cigarettes, or electric heat (such as hair dryers). Allow your hair to air-dry after you use this medicine.

Itching may last for 7 to 10 days after treatment. But itching is not a reason to use the product again. Overuse of lice products (such as using the product twice when only a single use is prescribed) can irritate the skin and may increase the risk of side effects.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

By Healthwise Staff
Primary Medical Reviewer John Pope, MD - Pediatrics
Specialist Medical Reviewer Susan C. Kim, MD - Pediatrics
Last Revised August 30, 2012

WebMD Medical Reference from Healthwise

Last Updated: August 30, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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