Treatment Options for Lice Infestation

Permethrin 1% lotion is the recommended first-line treatment for head lice due to its effectiveness and safety profile. 1

First-Line Treatment Options

Permethrin 1% cream rinse should be applied to hair that is first shampooed with a non-conditioning shampoo and towel dried, left on for 10 minutes, then rinsed off 2, 1
A second application of permethrin is necessary 7-10 days after the first treatment to kill newly emerged nymphs that may have hatched from eggs not killed during the initial treatment 2, 1
Permethrin has low mammalian toxicity and does not cause allergic reactions in patients with plant allergies 2
Pyrethrins plus piperonyl butoxide are an alternative first-line treatment, applied to dry hair and rinsed out after 10 minutes 2
When using pyrethrins, a second treatment is needed 7-10 days later as 20-30% of eggs remain viable after initial treatment 2, 3

Malathion 0.5% lotion is recommended when resistance to first-line treatments is documented or when permethrin or pyrethrins fail despite correct use 1
Malathion is applied to the hair, left to air dry, then washed off after 8-12 hours 2
Malathion has high ovicidal activity but should be used with caution due to its high alcohol content, flammability, and risk of severe respiratory depression if ingested 2, 4
Patients should be warned that malathion lotion is flammable and wet hair should not be exposed to open flames, electric heat sources, or cigarettes 4

Lindane 1% shampoo is not recommended as a first-line treatment due to safety concerns, particularly reports of seizures in children 2, 1
Lindane should only be used for patients who cannot tolerate or have not responded to safer medications 1
Lindane has low ovicidal activity and should be left on for no more than 10 minutes with a second application in 7-10 days 2

Oral agents such as sulfamethoxazole-trimethoprim and ivermectin are sometimes used but are not FDA-approved for treating head lice 2, 5
Oral ivermectin can be used as an alternative treatment at a single dose of 200 mg/kg, repeated in 10 days, but should not be used for children who weigh less than 15 kg 1, 6

After treatment with a pediculicide, removal of eggs is not necessary to prevent spreading the infestation but is recommended for aesthetic reasons 2
Vinegar or vinegar-based products applied to hair for 3 minutes before combing help loosen nits attached to the hair shaft 2, 1
Disinfect hats, hair ribbons, scarves, coats, towels, and bed linens by machine washing in hot water (above 54°C/130°F) and using the hottest dryer setting for at least 20 minutes 3
Soak all combs and brushes in hot water (above 54°C/130°F) for at least 10 minutes 3

All household members should be checked for lice infestation 7
Only those with live lice or eggs within 1 cm of the scalp should be treated 2, 7
Family members who share a bed with the infested person should be treated even if no live lice are found 7

Resistance to permethrin and pyrethrins has been reported, though the prevalence is unknown 2, 1
Treatment failure may be due to misdiagnosis, noncompliance with treatment protocol, reinfestation, lack of ovicidal properties of the treatment product, or resistance to the pediculicide 2, 6
Conditioners and silicone-based additives in shampoos can impair permethrin adherence to hair shafts and reduce effectiveness 7
Topical corticosteroids and oral antihistamines may be beneficial for relieving inflammation of the skin in response to topical treatments 2
Children with active head lice should be allowed to return to school after proper treatment and should not miss valuable school time because of head lice 2