Malathion for lice
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The medicine malathion is a safe treatment for lice.
Malathion lotion must be applied to hair and left on for 8 to 12 hours before rinsing off. A second treatment must be done 7 to 9 days later if lice are still present.1 Because the product contains alcohol, avoid sources of heat and open flame such as hair dryers, curling irons, fireplaces, and cigarettes until it has dried.
Why It Is Used
Malathion works very well against lice. However, it is less widely used than permethrin because treatment requires 8 to 12 hours.
Malathion is not recommended for use by pregnant women, nursing mothers, or children less 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.2
No serious side effects have been noted. However, the lotion has an unpleasant odor, may cause stinging (due to the alcohol content), and is able to catch fire until it dries. It may be too irritating to the skin to be used to treat pubic lice.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
Malathion works well as a treatment for head and pubic lice. But because it is less convenient to use, other products are more widely used.
Overuse of lice medications (such as reapplying the cream when only a single use is prescribed) can irritate the skin and may increase the risk of side effects from some products. It is common for itching to persist for 7 to 10 days after treatment. Itching is not a reason to treat the person again.
Malathion is not widely prescribed in the United States because of its strong odor, ability to catch on fire, and the time it takes for treatment to work.3 It can cause severe respiratory problems if swallowed.1
- American Academy of Pediatrics (2006). Pediculosis capitis (head lice), pediculosis corporis (body lice), pediculosis pubis (pubic lice). In LK Pickering, ed., Red Book: 2006 Report of the Committee on Infectious Diseases, 27th ed., pp. 488–493. Elk Grove Village, IL: American Academy of Pediatrics.
- Chosidow O (2000). Scabies and pediculosis. Lancet, 355: 819–826.
- Drugs for head lice (2005). Medical Letter on Drugs and Therapeutics, 47(1215/1216): 68–70.
Last Updated: November 24, 2008
Author: Debby Golonka, MPH