From the Guidelines
Visible nits typically require repeat lice treatment to ensure all lice and eggs are eliminated. The most recent and highest quality study, 1, published in 2017, recommends starting with over-the-counter topical 1% permethrin lotion or pyrethrin combined with piperonyl butoxide and repeating the treatment in 7 days. This approach is crucial because most treatments kill live lice but not all eggs, and the remaining eggs hatch within 7-10 days.
Key Points to Consider
- The standard treatment approach involves applying an over-the-counter pediculicide like permethrin 1% (Nix) or pyrethrin combined with piperonyl butoxide (RID, A-200) according to package directions, then repeating the treatment 7-10 days after the first application, as suggested by 1.
- During treatment, using a fine-toothed nit comb to physically remove nits from wet hair is essential, focusing on areas close to the scalp, behind ears, and the nape of the neck.
- Between treatments, continue combing every 2-3 days to remove any newly hatched lice before they mature and lay more eggs.
- For persistent infestations, prescription options like spinosad 0.9% (Natroba) or ivermectin 0.5% (Sklice) may be needed, as indicated by 1 and 1.
- Additionally, washing bedding, clothing, and personal items used within 48 hours in hot water and drying on high heat can help prevent reinfestation.
Treatment Options
- Over-the-counter pediculicides: permethrin 1% (Nix), pyrethrin combined with piperonyl butoxide (RID, A-200)
- Prescription options: spinosad 0.9% (Natroba), ivermectin 0.5% (Sklice)
Prevention of Reinfestation
- Wash bedding, clothing, and personal items used within 48 hours in hot water and dry on high heat
- Continue combing every 2-3 days to remove any newly hatched lice before they mature and lay more eggs.
From the FDA Drug Label
A second treatment must be done in 7-10 days to kill any newly hatched lice eggs (nits) if infestation continues, see a doctor for other treatments
- Visible nits indicate that a second treatment is necessary to kill any newly hatched lice.
- The drug label recommends a second treatment within 7 to 10 days to ensure that all lice and nits are eliminated.
- It is essential to repeat the treatment as directed to prevent reinfestation. 2
From the Research
Visible Nits and Lice Treatment
- The presence of visible nits, or louse egg shells, does not necessarily indicate an active infestation, as they can persist after successful treatment with no risk of transmission 3.
- Finding live lice is the most common method of diagnosing head lice infestations, while finding nits alone may indicate a historical infestation 3, 4.
- The "no nit" policy for schools and day care centers is no longer recommended, as nits can persist after successful treatment with no risk of transmission 3.
Treatment Effectiveness
- Spinosad 0.9% suspension is a topical treatment for head-lice infestation that has been shown to be effective in killing both permethrin-susceptible and permethrin-resistant populations of lice, as well as being ovicidal, killing both eggs (nits) and lice 5, 6, 7.
- Studies have demonstrated that spinosad is significantly more effective than permethrin in eradicating head lice, with most spinosad-treated participants requiring only one application 6, 7.
- The majority of subjects treated with spinosad 0.9% without nit combing required only a single treatment to eradicate head lice, while the majority of those treated with permethrin 1% with nit combing required two treatments 5.
Treatment Recommendations
- First-line pharmacologic treatment of pediculosis is permethrin 1% lotion or shampoo, although spinosad has shown superior performance compared to permethrin in some studies 3, 6.
- Wet combing is an effective nonpharmacologic treatment option for head lice infestations 3.
- Spinosad is a more convenient and effective treatment for pediculosis capitis, and most spinosad-treated participants required only one application 7.