What is the recommended treatment for pediculosis (lice infestation)?

Treatment of Lice (Pediculosis)

Permethrin 1% cream rinse applied to affected areas and washed off after 10 minutes is the first-line treatment for all types of lice infestations. 1, 2, 3

Type-Specific Treatment Approach

Head Lice (Pediculosis Capitis)

Primary Treatment:

• Apply permethrin 1% lotion to damp, towel-dried hair after shampooing with non-conditioning shampoo, leave on for 10 minutes, then rinse with warm water. 2
• A mandatory second application must be performed on day 7-10 to kill newly hatched nymphs, as permethrin has only 70-80% ovicidal activity. 2, 4

Alternative Options When First-Line Fails:

• Malathion 0.5% lotion applied for 8-12 hours has the highest ovicidal activity and should be used when resistance to permethrin is documented or treatment fails despite correct use. 1, 2
• Spinosad 0.9% topical suspension achieves high cure rates with a single 10-minute application to dry hair. 2
• Oral ivermectin 200 mcg/kg repeated in 10 days can be used, but avoid in children weighing less than 15 kg due to blood-brain barrier penetration risk. 2

Critical Management Points:

• Examine all household members with a magnifying glass in bright light; only treat those with live lice or eggs within 1 cm of scalp. 2, 4
• Post-treatment itching persists for days and is NOT treatment failure—treat with topical corticosteroids or oral antihistamines. 2
• Use a fine-toothed nit comb on damp hair to remove eggs; this may take 1-2 hours for longer hair. 4

Pubic Lice (Pediculosis Pubis)

Primary Treatment:

• Permethrin 1% cream rinse applied to affected areas and washed off after 10 minutes. 1, 3
• Alternatively, pyrethrins with piperonyl butoxide applied to affected area and washed off after 10 minutes. 1

When Resistance Suspected:

• Malathion 0.5% lotion applied for 8-12 hours. 1
• Ivermectin 250 mcg/kg orally repeated in 2 weeks (limited ovicidal activity requires the second dose). 1

Essential Considerations:

• Sexual partners within the previous month must be treated simultaneously to prevent reinfection. 1, 3
• Evaluate all patients for other sexually transmitted infections including HIV. 1
• Do NOT apply to eyes; for eyelash infestations, apply occlusive ophthalmic ointment or petroleum jelly to eyelid margins twice daily for 10 days. 1, 3

Body Lice (Pediculosis Corporis)

Primary Approach:

• Machine washing all infested clothing, bedding, and linens in hot water (above 54°C/130°F) and drying using the hot cycle is often sufficient without medication. 5
• If washing not immediately possible, remove items from body contact for at least 72 hours. 5

When Medication Needed:

• Permethrin 1% cream rinse applied to affected body areas and washed off after 10 minutes. 5
• Alternatively, pyrethrins with piperonyl butoxide. 5

Environmental Decontamination (All Types)

• Machine wash and dry all bedding, clothing, and linens using hot water and the hottest dryer setting for at least 20 minutes. 4, 6
• Soak all combs and brushes in hot water above 54°C (130°F) for at least 10 minutes. 4
• Items that cannot be washed should be dry-cleaned or sealed in plastic bags for 72 hours. 1, 5
• Fumigation of living areas is NOT necessary. 1, 5

Special Populations

Pregnant and Lactating Women:

• Use permethrin or pyrethrins with piperonyl butoxide—these are safe options. 1, 5, 3
• Avoid lindane completely due to risk of neural tube defects and accumulation in breast milk. 1

Children:

• Permethrin 1% is safe and effective. 2
• Avoid lindane in children under 10 years due to seizure risk. 1
• Avoid oral ivermectin in children under 15 kg. 2

Treatments to Avoid

Lindane:

• Should only be used when other therapies cannot be tolerated or have failed due to neurotoxicity risk (seizures, aplastic anemia). 1, 2
• Never use in pregnant/lactating women, children under 10 years, or immediately after bathing. 1
• Has low ovicidal activity (30-50% of eggs survive) and widespread resistance. 2

Unsafe Home Remedies:

• Never use kerosene, alcohol, or insecticides—these are dangerous and ineffective. 7

Follow-Up Protocol

• Re-evaluate after 1 week if symptoms persist. 1
• Re-treatment is necessary only if live lice are found or eggs are observed at the hair-skin junction. 1
• If no response to recommended regimen, switch to an alternative agent rather than repeating the same treatment. 1
• Check daily for missed lice/eggs during the first week. 4

Common Pitfalls

• Improper application is the most common cause of treatment failure, not resistance—ensure adequate contact time and complete coverage. 2
• "No nit" policies for schools are no longer recommended as nits alone indicate historical infestation with no transmission risk. 6
• Avoid using conditioning shampoos before permethrin application as they reduce efficacy. 2
• Do not spray or fog homes with insecticides—this is ineffective and potentially harmful. 8