What is the recommended treatment for a pediatric patient with a head lice infestation?

Treatment of Head Lice in Pediatric Patients

Permethrin 1% cream rinse applied to damp, towel-dried hair for exactly 10 minutes, followed by a mandatory second application 7-10 days later, is the recommended first-line treatment for head lice in children. 1, 2

First-Line Treatment: Permethrin 1%

Application technique:

• Shampoo hair with non-conditioning shampoo first, then towel dry until damp (not soaking wet) 2, 3
• Apply permethrin 1% cream rinse to damp hair and scalp 1, 2
• Leave on for exactly 10 minutes—not longer or shorter 3
• Rinse thoroughly with warm water over a sink to limit skin exposure 1, 3
• Mandatory second application in 7-10 days to kill newly hatched nymphs, as permethrin has only 70-80% ovicidal activity 1, 2, 3

Safety profile:

• Low mammalian toxicity and does not cause allergic reactions in patients with plant allergies 1, 2
• Safe and effective, with 99% cure rates in clinical trials 4

Second-Line Treatment: Malathion 0.5%

Switch to malathion 0.5% if live lice are confirmed 7-10 days after a second properly applied permethrin treatment—do not apply permethrin a third time, as this indicates likely resistance. 1

Application technique:

• Apply to dry hair and allow to air dry naturally 1, 2
• Leave on for 8-12 hours before washing off 1, 2
• Has the highest ovicidal activity (~98%) of all treatments, often requiring only a single application 1, 2
• Reapply in 7-9 days only if live lice are still present 1

Critical safety warnings:

• Contains 78% isopropyl alcohol—highly flammable 2
• Keep away from open flames, hair dryers, and sparks 2
• Approved for children ≥6 months, contraindicated in children <24 months 1
• Risk of severe respiratory depression if ingested 1

Alternative First-Line Option: Spinosad 0.9%

Spinosad 0.9% topical suspension achieves high cure rates with a single 10-minute application and is FDA-approved for children ≥6 months. 1, 5

Application technique:

• Apply to dry scalp and dry hair 5
• Use up to 120 mL (one bottle) to adequately cover scalp and hair 5
• Leave on for 10 minutes, then rinse thoroughly with warm water 1, 5
• If live lice are seen 7 days after first treatment, apply a second treatment 5

Safety considerations:

• Contains benzyl alcohol—not approved for neonates and infants below 6 months 5
• Apply only under direct adult supervision in pediatric patients 5

Treatments to Avoid

Lindane 1% should not be used as first-line treatment due to severe safety concerns, including seizure risk, neurotoxicity, low ovicidal activity (30-50%), and widespread resistance. 1, 2

Oral ivermectin is not FDA-approved for pediculosis and should not be used in children under 15 kg due to blood-brain barrier penetration risk. 1

Who to Treat

• Examine all household members for lice 1
• Treat only individuals with live lice or nits within 1 cm of the scalp 1, 2
• Treat family members who share a bed with the infected person 2

Environmental Decontamination

• Wash all clothing, bedding, linens, and hair care items in hot water and dry on hot cycle on the same day as treatment 2, 3
• Remove items that cannot be washed from body contact for at least 72 hours, as lice cannot survive off the human body for more than 2-3 days 2, 3
• Fumigation of living areas is not necessary 3

Adjunctive Nit Removal (Optional)

• Nit removal is not necessary to prevent spread but can help decrease diagnostic confusion 2
• Apply vinegar or vinegar-based products to hair for 3 minutes before combing to help loosen nits 1
• Use a fine-tooth nit comb after treatment 2

Critical Pitfalls to Avoid

Post-treatment itching is NOT a sign of treatment failure and persists for days due to inflammatory response—do not retreat based on itching alone. 1, 2, 3

Most "resistance" is actually due to improper application—before assuming resistance, consider:

• Misdiagnosis (nits alone without live lice) 2
• Noncompliance with treatment instructions 2
• Reinfestation from untreated household contacts 1
• Improper application technique (using conditioning shampoo, not leaving on for full 10 minutes, rinsing with hot water instead of warm) 1, 3

Retreat only if live lice are seen 7-10 days after treatment, not based on itching or presence of nits alone. 2, 3

Do not use conditioning shampoo before applying permethrin, as it prevents proper adherence to the hair shaft. 3

Do not skip the mandatory second application of permethrin at 7-10 days, as incomplete egg kill necessitates this step. 3