Head Lice Treatment
Permethrin 1% cream rinse is the recommended first-line treatment for head lice, applied to damp, shampooed, towel-dried hair for 10 minutes, then rinsed off, with a second application in 7-10 days. 1
First-Line Treatment: Permethrin 1%
- Apply permethrin 1% cream rinse to damp hair that has been shampooed with a non-conditioning shampoo and towel-dried 2
- Leave on for exactly 10 minutes, then rinse thoroughly 2, 1
- The residue left after rinsing continues to kill nymphs emerging from eggs that survived the first application 2
- Repeat application in 7-10 days if live lice are observed to kill newly hatched nymphs 2, 1
- Permethrin has low mammalian toxicity and does not cause allergic reactions in patients with plant allergies 2, 1
- Superior efficacy compared to lindane: 99% cure rate at 14 days versus 85% with lindane 3
Second-Line Treatment: Pyrethrins Plus Piperonyl Butoxide
- Apply to dry hair and rinse out after 10 minutes 2, 4
- These agents are neurotoxic to lice with extremely low mammalian toxicity 2
- Avoid in patients allergic to chrysanthemums 2
- 20-30% of eggs remain viable after treatment, necessitating a second treatment in 7-10 days 2
- Resistance has been reported, though prevalence is unknown 2
Treatment for Resistant Cases: Malathion 0.5%
- Reserved for documented resistance to permethrin or pyrethrins, or when first-line treatments fail despite correct use 1
- Apply to dry hair, allow to air dry naturally, then wash off after 8-12 hours 2, 5
- Has high ovicidal activity but requires reapplication if live lice are seen in 7-10 days 2, 5
- Critical safety warnings: highly flammable due to high alcohol content; use no electric heat source while hair is drying 2, 5
- Risk of severe respiratory depression if ingested 2
- Not for use in children under 24 months 6
Treatment to Avoid: Lindane 1%
- The American Academy of Pediatrics does not recommend lindane as first-line treatment due to safety concerns 1
- Should only be used when patients cannot tolerate or have failed safer medications 1
- Multiple cases of seizures in children have been reported 2
- Low ovicidal activity (30-50% of eggs not killed) 1
- Worldwide resistance documented 2
- Contraindicated in children weighing less than 50 kg, pregnant/lactating women, and those with seizure disorders 6
Alternative Treatment: Oral Ivermectin
- Single dose of 200 mcg/kg, repeated in 10 days 1
- Should not be used in children weighing less than 15 kg due to risk of crossing the blood-brain barrier 1
- Not FDA-approved for pediculosis but sometimes used off-label 2
Household Management Algorithm
Step 1: Examination
- Examine all household members with a magnifying glass in bright light 2, 4
- Look for live lice or eggs (nits) within 1 cm of the scalp 2, 1
Step 2: Selective Treatment
- Treat only those with live lice or eggs within 1 cm of scalp 2, 1
- Treat family members who share a bed with the infected person 2
Step 3: Environmental Measures
- Clean hair care items and bedding belonging to infected person 2
- Machine wash in hot water above 54°C (130°F) and use hottest dryer setting for at least 20 minutes 4
Nit Removal (Optional)
- Nit removal after treatment is not necessary to prevent spread but recommended for aesthetic reasons or to decrease diagnostic confusion 2
- Apply vinegar or vinegar-based products to hair for 3 minutes before combing to help loosen nits 2, 1
- Use a fine-toothed nit comb to remove dead lice and eggs 5, 4
Common Pitfalls to Avoid
Treatment Failure Considerations:
- Before assuming resistance, consider: misdiagnosis, noncompliance with treatment protocol, reinfestation, lack of ovicidal properties, or improper application 2, 1
- Improper application is the most common cause of treatment failure 1
Post-Treatment Symptoms:
- Itching or mild burning of the scalp after treatment is common and not a reason for re-treatment 1
- Topical corticosteroids and oral antihistamines may relieve post-treatment inflammation 2, 1
School Attendance: