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Other drug names: A-Am An-Az B C-Ch Ci-Cz D-Dh Di-Dz E F G H I-J K-L M-Mh Mi-Mz N-Nh Ni-Nz O P-Pl Pm-Pz Q-R S-Sn So-Sz T-To Tp-Tz U-V W-Z 0-9   

Malathion (Topical)

Brand Names

In the U.S.-

  • Ovide


  • Pediculicide


Malathion ( mal-a-THYE-on) belongs to the group of medicines known as pediculicides (medicines that kill lice).

Malathion is applied to the hair and scalp to treat head lice infections. It acts by killing both the lice and their eggs.

This medicine is available only with your doctor's prescription, in the following dosage form:

  • Lotion (U.S.)

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For malathion, the following should be considered:

Allergies- Tell your doctor if you have ever had any unusual or allergic reaction to malathion. Also tell your health care professional if you are allergic to any other substances, such as preservatives or dyes.

Pregnancy- Malathion may be absorbed through the skin. Although it has not been studied in pregnant women, malathion has not been shown to cause birth defects or other problems in animal studies.

Breast-feeding- Malathion may be absorbed through the mother's skin. It is not known whether malathion passes into the breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are using this medicine and who wish to breast-feed should discuss this with their doctor.

Children- This medicine has been tested in children 6 years of age and older and, in effective doses, has not been shown to cause different side effects or problems than it does in adults. There is no specific information comparing use of malathion in children less than 6 years of age with use in other age groups.

Older adults- Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of malathion in the elderly with use in other age groups.

Other medicines- Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are using malathion, it is especially important that your health care professional know if you are using any of the following:

  • Antimyasthenics (ambenonium, neostigmine, pyridostigmine) or
  • Demecarium, echothiophate, or isoflurophate eye medicine-Use of malathion with these medicines may increase the chance of side effects

Other medical problems- The presence of other medical problems may affect the use of malathion. Make sure you tell your doctor if you have any other medical problems, especially:
  • Anemia (severe) or
  • Brain surgery, recent, or
  • Liver disease or
  • Malnutrition-These conditions may increase the chance of some side effects of malathion
  • Asthma or
  • Epilepsy or other seizure disorders or
  • Heart disease or
  • Myasthenia gravis or other nerve/muscle disease or
  • Parkinson's disease or
  • Stomach ulcer or other stomach or intestinal problems-Use of malathion may make the condition worse

Proper Use of This Medicine

. Malathion may cause you to be very sick if it is not used correctly. Do not use it in the mouth because it is harmful if swallowed.

Use this medicine only as directed by your doctor . Do not use more of it, do not use it more often, and do not use it for a longer time than your doctor ordered. To do so may increase the chance of absorption through the skin and the chance of becoming very sick.

To use:

  • Apply malathion by sprinkling on dry hair and rubbing in until the hair and scalp are thoroughly moistened.
  • Immediately after using this medicine, wash your hands to remove any medicine that may be on them.
  • Allow the hair to dry naturally. Use no heat (as from a hair dryer) and leave the hair uncovered.
  • After the medicine has been allowed to remain on the hair and scalp for 8 to 12 hours, wash the hair with a nonmedicated shampoo and then rinse thoroughly .
  • After rinsing, use a fine-toothed comb to remove the dead lice and eggs from the hair.

Keep this medicine away from the eyes . If you should accidentally get some in your eyes, flush them thoroughly with water at once.

This medicine is flammable. Do not use near heat, near open flame, or while smoking.

Head lice can be easily transferred from one person to another by direct contact with clothing, hats, scarves, bedding, towels, washcloths, hairbrushes and combs, or hairs from infected persons. Therefore, all household members of your family should be examined for head lice and receive treatment if they are found to be infected . If you have any questions about this, check with your doctor.


The dose of malathion will be different for different patients. Follow your doctor's orders or the directions on the label . The following information includes only the average doses of malathion. If your dose is different, do not change it unless your doctor tells your to do so.

  • For lotion dosage form:
    • For head lice infestations:
      • Adults and children 6 years of age and older-Apply to the hair and scalp one time. Treatment may be repeated after seven to nine days if necessary.
      • Children up to 6 years of age-Use and dose must be determined by your doctor.


To store this medicine:

  • Keep out of the reach of children.
  • Flammable. Keep away from heat and open flame.
  • Store away from heat and direct light.
  • Keep the medicine from freezing.
  • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Precautions While Using This Medicine

To prevent reinfection or the spreading of the infection to other people, good health habits are also required. These include the following:

  • Wash all clothing, bedding, towels, and washcloths in very hot water or dry-clean them.
  • Wash all hairbrushes and combs in very hot soapy water and do not share them with other people.
  • Clean the house or room by thorough vacuuming.

If you have any questions about this, check with your doctor.

Breathing in even small amounts of carbamate- or organophosphate-type insecticides or pesticides (for example, carbaryl [Sevin], demeton [Systox], diazinon, malathion, parathion, ronnel [Trolene]) may add to the effects of this medicine. Farmers, gardeners, residents of communities undergoing insecticide or pesticide spraying or dusting, workers in plants manufacturing such products, or other persons exposed to such poisons should protect themselves by wearing a mask over the nose and mouth, changing clothes frequently, and washing hands often while using this medicine.

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • Rare
    • Skin rash 

When malathion is applied to the skin in recommended doses, symptoms of poisoning have not been reported. However, the chance may exist, especially if the skin is broken. Symptoms of malathion poisoning include:

  • Abdominal or stomach cramps;  anxiety or restlessness;  clumsiness or unsteadiness;  confusion or mental depression;  convulsions (seizures);  diarrhea;  difficult or labored breathing;  dizziness;  drowsiness;  increased sweating;  increased watering of mouth or eyes;  loss of bowel or bladder control;  muscle twitching of eyelids, face, and neck;  pinpoint pupils;  slow heartbeat;  trembling;  unusual weakness 

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if either of the following side effects continues or is bothersome:

  • Less common or rare
    • Redness, pain, swelling of eye, eyelid, inner lining of eyelid; burning, dry or itching eyes, discharge, excessive tearing;  stinging or irritation of scalp 

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT