From the Guidelines
The recommended treatment for head lice in adults is permethrin 1% (Nix) applied to damp hair for 10 minutes before rinsing, as it has low mammalian toxicity and is relatively safe for humans when used as directed 1. This treatment should be repeated after 7-10 days to kill newly hatched lice.
- Permethrin is a synthetic pyrethroid with extremely low mammalian toxicity, making it a safe option for adults.
- The product is applied to damp hair that is first shampooed with a nonconditioning shampoo and then towel dried.
- It is left on for 10 minutes and then rinsed off, leaving a residue on the hair that is designed to kill nymphs emerging from the eggs not killed with the first application.
- For resistant cases, prescription options include malathion 0.5% (Ovide), which is left on dry hair for 8-12 hours, or ivermectin lotion 0.5% (Sklice), applied for 10 minutes 1.
- Alongside medication, use a fine-toothed lice comb to remove lice and nits, especially from behind ears and near the neckline.
- Wash bedding, clothing, and personal items in hot water (at least 130°F) and dry on high heat.
- Seal non-washable items in plastic bags for two weeks to prevent re-infestation. It is also important to note that all household members should be checked, and only those with live lice or eggs within 1 cm of the scalp should be treated 1.
From the FDA Drug Label
Apply malathion lotion on DRY hair in amount just sufficient to thoroughly wet the hair and scalp. Pay particular attention to the back of the head and neck while applying malathion lotion. Malathion lotion is indicated for patients infected with Pediculus humanus capitis (head lice and their ova) of the scalp hair.
The recommended treatment for head lice in adults is to apply malathion lotion on dry hair, thoroughly wetting the hair and scalp, and paying particular attention to the back of the head and neck. After 8 to 12 hours, shampoo the hair and use a fine-toothed comb to remove dead lice and eggs. If lice are still present after 7-9 days, repeat with a second application of malathion lotion 2. Malathion lotion is indicated for patients infected with head lice and their ova of the scalp hair 2.
From the Research
Head Lice Treatment for Adults
The recommended treatment for head lice in adults includes:
- Malathion lotion 0.5% repeated in one week, left on for 30 minutes to 8 hours 3
- Spinosad topical suspension 0.9% repeated in one week, left on for 10 minutes 3, 4
- Oral ivermectin 200 mcg/kg, repeated in four days, may be considered for difficult-to-treat cases 5
Treatment Options and Efficacy
- Malathion lotion 0.5% has been shown to be effective in treating head lice, but resistance is a growing concern 6
- Spinosad has demonstrated superior performance compared to permethrin, with 82.5% and 86.1% of patients free of live lice 14 days after treatment 4
- Oral ivermectin has been shown to have superior efficacy compared to topical 0.5% malathion lotion, with 95.2% of patients lice-free on day 15 5