From the Guidelines
The most effective treatment for lice is permethrin 1% cream rinse, which should be applied to dry hair, left on for 10 minutes, and then rinsed off, with a repeat treatment in 7-10 days to kill newly hatched lice. This recommendation is based on the most recent and highest quality study available, which suggests that permethrin 1% is the least toxic to humans and has extremely low mammalian toxicity 1. The treatment should be applied to damp hair that is first shampooed with a nonconditioning shampoo and then towel dried. It is essential to note that conditioners and silicone-based additives present in almost all currently available shampoos impair permethrin adherence to the hair shaft and reduce its residual effect.
Some key points to consider when treating lice include:
- Permethrin 1% cream rinse is the recommended first-line treatment for head lice 1
- The treatment should be repeated in 7-10 days to kill newly hatched lice 1
- Mechanical removal with a fine-toothed comb is essential after treatment to remove dead lice and nits
- Household items that may harbor lice should be washed in hot water (at least 130°F) or sealed in plastic bags for two weeks
- Family members and close contacts should be examined and treated if infested
Other treatment options, such as malathion 0.5% (Ovide) and ivermectin lotion 0.5% (Sklice), may be considered for resistant cases or when permethrin 1% is not effective 1. However, these treatments should be used with caution and under the guidance of a healthcare professional.
It is also important to note that "natural" products, such as essential oils, have been widely used in traditional medicine for the eradication of head lice, but their safety and efficacy are not regulated by the FDA and may not be reproducible 1. Therefore, these products should be used with caution and under the guidance of a healthcare professional.
From the FDA Drug Label
Package Insert Consumer Information LICE KILLING SHAMPOO For the treatment of Head Lice, Pubic (Crab) Lice and Body Lice Treat apply thoroughly to dry hair or other affected area. a second treatment must be done in 7-10 days to kill any newly hatched lice eggs (nits)
The treatment (tx) for lice is to apply the pyrethrin shampoo thoroughly to dry hair or other affected area, and then repeat the treatment in 7-10 days to kill any newly hatched lice eggs (nits) 2.
- For head lice, apply the shampoo behind the ears and to the back of the neck, allow it to remain for 10 minutes, then rinse and comb out lice and eggs (nits).
- For pubic (crab) lice and body lice, disinfect affected areas and items, and treat sexual partners simultaneously to avoid reinfestation.
From the Research
Treatment Options for Lice
- Over-the-counter medications such as permethrin and pyrethrin 3
- Prescription medicines including malathion, lindane, benzyl alcohol, and spinosad 3
- Alternative medicine and physical treatment modalities, such as the use of hot air to kill head lice and their eggs 4
Efficacy of Treatment Options
- A combination of 1% permethrin and trimethoprim/sulfamethoxazole has been shown to be an effective alternative therapy for head lice infestation, with a success rate of 95% at the 2-week follow-up visit 5
- Spinosad has been found to be an effective and well-tolerated agent for the treatment of head lice, with a success rate of 84.6% and 86.7% in two trials 6
- A single application of 1% permethrin cream rinse has been shown to be highly effective, with 99% of patients being lice free at 14 days 7
Non-Chemical Treatment Options
- The use of hot air to kill head lice and their eggs has been found to be an effective and safe treatment option, with a custom-built machine called the LouseBuster resulting in nearly 100% mortality of eggs and 80% mortality of hatched lice 4