What is the recommended treatment for pediculosis capitis?

Treatment for Pediculosis Capitis (Head Lice)

First-line treatment for head lice is topical permethrin 1% or malathion 0.5% lotion, with malathion showing superior efficacy in clinical trials. 1

First-Line Topical Pediculicides

Malathion 0.5% Lotion (Preferred)

• Apply to dry hair and scalp in sufficient quantity to thoroughly wet the hair, allow to air dry naturally, then shampoo after 8-12 hours 1
• Clinical trials demonstrate 88% of patients remain lice-free at 7 days after a single application 1
• Repeat application in 7-9 days if live lice are still present; further treatment is generally not necessary 1
• Critical safety warning: Malathion is flammable—avoid open flames, electric heat sources, hair dryers, and smoking while hair is wet 1
• Must be used under direct adult supervision in children 1

Permethrin 1% (Over-the-Counter Alternative)

• Available without prescription as cream rinse or lotion 2
• Apply to clean, towel-dried hair, leave on for 10 minutes, then rinse 2
• Repeat application in 9-10 days is necessary due to limited ovicidal activity 2
• Increasing resistance has been documented, making malathion a more reliable choice 2, 3

Second-Line Options for Treatment Failures

Spinosad 0.9% Suspension

• Significantly more effective than permethrin, with most patients requiring only a single treatment 3
• Kills both lice and nits (ovicidal), eliminating the need for nit combing 3
• Effective against permethrin-resistant lice populations 3
• Apply to dry hair, leave for 10 minutes, then rinse 3
• Well tolerated with minimal adverse events (cutaneous and ocular irritation most common) 3

Oral Ivermectin

• Use 200 μg/kg orally, repeated in 10 days, for cases resistant to topical treatments 2
• More recent data supports 400 μg/kg repeated in 7 days as more effective than malathion 2
• Contraindicated in children weighing less than 15 kg due to risk of crossing the blood-brain barrier 2
• Not FDA-approved as a pediculicide but effective in clinical practice 2

Treatments to Avoid

Lindane 1% (Not Recommended)

• The American Academy of Pediatrics no longer recommends lindane for pediculosis 2
• Central nervous system toxicity with reported severe seizures in children 2
• Low ovicidal activity (30-50% of eggs survive) and widespread resistance 2
• Banned in California and contraindicated in children under 50 kg 2

Permethrin 5% Cream

• Not FDA-approved for head lice 2
• Evidence suggests lice resistant to 1% permethrin will not respond to higher concentrations 2

Essential Management Principles

Application Technique

• Rinse all topical pediculicides over a sink (not shower/bath) with warm water to minimize systemic absorption 2
• Apply sufficient product to thoroughly wet all hair and scalp, paying particular attention to the back of the head and neck 1
• Allow hair to dry naturally and remain uncovered after application 1

Post-Treatment Expectations

• Itching and mild scalp burning can persist for many days after lice are killed and is not a reason for re-treatment 2
• Topical corticosteroids and oral antihistamines may relieve persistent symptoms 2
• Use a fine-toothed nit comb to remove dead lice and eggs after shampooing 1

Environmental Decontamination

• Clean contaminated combs and brushes with disinfectant or 2% sodium hypochlorite solution 4
• Avoid sharing towels and personal items 4
• Screen and treat all close contacts and family members 4, 5
• Spraying or fogging homes with insecticides is not recommended 5

Common Pitfalls to Avoid

• Do not retreat based on persistent itching alone—this is an inflammatory response, not treatment failure 2
• Do not use lindane as first-line therapy due to neurotoxicity and resistance 2
• Ensure adequate contact time for topical agents—insufficient application time is a common cause of treatment failure 1
• Do not expose malathion-treated hair to heat sources—serious burns can occur 1
• Verify live lice are present before initiating treatment; nits alone may represent old, non-viable eggs 5