What is the treatment for pediculosis (lice infestation)?

From the Guidelines

To treat head lice, use over-the-counter pediculicides containing permethrin 1% (like Nix) or pyrethrin with piperonyl butoxide (like RID), as these are the most effective and safest options available, with low mammalian toxicity and minimal risk of adverse effects 1. When using these medications, apply them to dry hair, leave them on for 10 minutes, and then rinse. It is essential to repeat the treatment after 7-10 days to kill newly hatched lice. For resistant cases, prescription options include malathion 0.5% (Ovide), benzyl alcohol 5% (Ulesfia), ivermectin 0.5% (Sklice), or spinosad 0.9% (Natroba) 1. Some key points to consider when treating head lice include:

• Supplementing treatment by removing nits with a fine-toothed comb after application
• Washing all bedding, clothing, and personal items used in the past 48 hours in hot water (130°F) and drying them on high heat
• Sealing non-washable items in plastic bags for two weeks
• Vacuuming furniture and floors where the infested person sat or lay Lice treatments work by paralyzing the nervous system of the lice, causing their death, while combing physically removes both lice and their eggs. Treatment failure usually occurs due to improper application, insufficient contact time, or resistance to the medication, making proper application and follow-up treatment essential 1.

From the FDA Drug Label

Malathion lotion is indicated for patients infected with Pediculus humanus capitis (head lice and their ova) of the scalp hair. Apply malathion lotion on the scalp hair in an amount just sufficient to thoroughly wet hair and scalp Pay particular attention to the back of the head and neck when applying malathion lotion. Allow hair to dry naturally and to remain uncovered. Shampoo hair after 8 to 12 hours, again paying attention to the back of the head and neck while shampooing Rinse hair and use a fine - toothed (nit) comb to remove dead lice and eggs. If lice are still present after 7 - 9 days, repeat with a second application of malathion lotion.

Lice Treatment with Malathion Lotion:

• Malathion lotion is used to treat head lice and their ova in scalp hair.
• The lotion should be applied to thoroughly wet hair and scalp, paying attention to the back of the head and neck.
• After application, allow hair to dry naturally and remain uncovered.
• Shampoo hair after 8 to 12 hours and use a fine-toothed comb to remove dead lice and eggs.
• If lice are still present after 7-9 days, a second application of malathion lotion may be necessary 2, 2.

From the Research

Lice Treatment Options

• There are several treatment options available for head lice, including dimeticone liquid gel, permethrin creme rinse, spinosad creme rinse, and malathion.
• A study published in 2013 found that a single application of 4% dimeticone liquid gel was more effective than two applications of 1% permethrin creme rinse in treating head louse infestation 3.
• Another study published in 2009 found that spinosad creme rinse was more effective than permethrin creme rinse in treating pediculosis capitis, with 84.6% and 86.7% of spinosad-treated participants being lice-free compared to 44.9% and 42.9% of permethrin-treated participants 4.

Permethrin Treatment

• Permethrin is a commonly used treatment for head lice, but its efficacy has been shown to vary depending on the method of application.
• A study published in 2023 found that using 1% permethrin shampoo for 1 hour was more effective in eradicating head lice within the first week of treatment and in relieving scalp itching during the second week compared to other methods of permethrin application 5.
• However, another study published in 2013 found that permethrin had low efficacy, with only 14.9% of participants being lice-free after treatment, and suggested that it should be withdrawn as a treatment option 3.

Alternative Treatment Options

• Malathion is an alternative treatment option for head lice, with efficacy rates of 97-98% reported in recent studies 6.
• Malathion is also a reasonable alternative to permethrin 5% cream for treating scabies, especially when treatment of the scalp or hairy areas is desired 6.
• Spinosad creme rinse is also a effective treatment option for pediculosis capitis, with no need for nit combing 4.