Generic Name: malathion (mal-a-THYE-on)
Medically reviewed by Drugs.com. Last updated on Oct 29, 2020.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Pediculicide
Chemical Class: Organophosphate
Uses for malathion
Malathion topical lotion is used to treat head lice infections. It belongs to the group of medicines known as pediculicides (medicines that kill lice). Malathion acts by killing both the lice and their eggs.
Malathion is available only with your doctor's prescription.
Before using malathion
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:
Tell your doctor if you have ever had any unusual or allergic reaction to malathion or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of malathion topical in children younger than 6 years of age. Safety and efficacy have not been established. However, use of malathion in newborn and infants younger than 1 year of age is not recommended.
No information is available on the relationship of age to the effects of malathion topical in geriatric patients.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with 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. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
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—May make these conditions worse.
Proper use of malathion
Use malathion exactly 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 absorbing the medicine and the chance of becoming very sick.
Use malathion on the hair and scalp only. Keep your eyes tightly closed while applying malathion. If skin irritation occurs, wash your hair and scalp right away.
Malathion may cause you to be very sick if it is not used correctly. Call a doctor or poison control center right away if you accidentally swallow malathion.
- Apply the lotion by sprinkling on dry hair and rubbing in until the hair and scalp are thoroughly moistened.
- Wash your hands right away after using the medicine. This is 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 non-medicated shampoo and then rinse thoroughly.
- After rinsing, use a fine-toothed (nit) comb to remove the dead lice and eggs from the hair.
- If lice are still present after 7 to 9 days, repeat with a second application of malathion lotion.
- Malathion is flammable. Keep the lotion and hair wet with lotion away from open flames. Do not use electric heat sources such as hair dryers and curlers when you apply malathion, or while your hair is wet. Do not smoke while applying malathion or while hair is wet. Let your hair to dry naturally.
Keep malathion away from your eyes. If you should accidentally get some in your eyes, wash your eyes with water at once and check with your doctor right away.
Do not use cosmetics and other hair products on the treated hair and scalp areas.
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 you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For topical dosage form (lotion):
- For head lice infestations:
- Adults, teenagers, and children 6 years of age and older—Apply to the hair and scalp one time. Treatment may be repeated after 7 to 9 days, if necessary.
- Children 1 to 6 years of age—Use and dose must be determined by your doctor.
- Infants younger than 1 year of age—Use is not recommended.
- For head lice infestations:
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep the medicine away from heat or open flame.
Precautions while using malathion
Do not use malathion on your child unless approved by your doctor.
Head lice can be easily spread from one person to another by direct contact with clothing, hats, scarves, bedding, towels, washcloths, hairbrushes and combs, or hairs from infected persons. All members of your household should be checked for head lice and receive treatment if they are found to be infected. If you have any questions about this, check with your doctor.
To prevent spread of lice to other people, good health habits are also required. These include the following:
- Dry-clean or wash all clothing, bedding, and personal items (including washcloths, towels, hats, scarves, combs, brushes, hairpieces, and wigs) in hot, soapy water.
- Clean the house or room by thorough vacuuming.
Skin irritation may occur while using the medicine. If it occurs, wash scalp and hair right away and check with your doctor.
Call your doctor right away if you have burns (including second-degree burns) and stinging sensation after using malathion.
Breathing in even small amounts of carbamate- or organophosphate-type insecticides or pesticides (e.g., carbaryl [Sevin®], demeton [Systox®], diazinon, malathion, parathion, or ronnel [Trolene®]) may add to the effects of malathion. 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 malathion.
Do not use malathion for a hair or scalp problem that has not been checked by your doctor.
Malathion side effects
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 immediately if any of the following side effects occur:
- Skin rash
Incidence not known
- Blistering and peeling of the skin
- reddened skin
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- Abdominal or stomach cramps
- anxiety or restlessness
- clumsiness or unsteadiness
- confusion or mental depression
- convulsions (seizures)
- difficult or labored breathing
- increased sweating
- increased watering of the mouth or eyes
- loss of bowel or bladder control
- muscle twitching of the eyelids, face, and neck
- pinpoint pupils
- slow heartbeat
- unusual weakness
Some 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. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common or rare
- Burning, dry, or itching eyes
- discharge or excessive tearing
- redness, pain, or swelling of the eye, eyelid, inner lining of the eyelid
- stinging or irritation of the scalp
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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