Permethrin Treatment for Scabies and Lice Infestations
For scabies, permethrin 5% cream should be applied to the entire body from the neck down and washed off after 8-14 hours, while for lice, permethrin 1% creme rinse should be applied to affected areas and washed off after 10 minutes. 1
Scabies Treatment
First-Line Treatment
- Permethrin cream (5%) applied to all areas of the body from the neck down and washed off after 8-14 hours 1, 2
- For infants, treatment should include the scalp, temple, and forehead areas 2
- Usually 30 grams is sufficient for an average adult 2
- One application is generally curative, though persistent pruritus after treatment is common and not necessarily a sign of treatment failure 2
Alternative Treatments
- Lindane (1%) lotion or cream applied thinly to all areas from the neck down and washed off after 8 hours 1
- Sulfur (6%) precipitated in ointment applied nightly for 3 nights 1
- Ivermectin (oral 200 μg/kg) may be considered for treatment-resistant cases 1, 3
Special Considerations
- Lindane should NOT be used after bathing, in persons with extensive dermatitis, pregnant/lactating women, or children under 2 years 1
- Permethrin is safer than lindane, which has been associated with seizures and aplastic anemia 1
- For pregnant women and young children, permethrin is the preferred treatment 1, 4
- For crusted scabies, oral ivermectin may be more effective 5
Lice Treatment
Head and Pubic Lice
- Permethrin 1% creme rinse applied to affected areas and washed off after 10 minutes 1, 6
- Pyrethrins with piperonyl butoxide is an alternative treatment 1
- For eyelash infestations, apply occlusive ophthalmic ointment to eyelid margins twice daily for 10 days 1
Treatment Failures
- Re-evaluate after 1 week if symptoms persist 1
- Re-treatment may be necessary if live lice are found or eggs are observed at the hair-skin junction 1
- Malathion can be considered for treatment failures 5, 3
Environmental Measures
For Both Scabies and Lice
- Bedding and clothing should be decontaminated by machine washing or drying using hot cycles (60°C for 10 minutes) or dry-cleaning 1, 3
- Alternatively, remove items from body contact for at least 72 hours 1
- Fumigation of living areas is not necessary 1
Contact Management
- For lice: Sexual partners within the preceding month should be treated 1
- For scabies: Both sexual and close personal/household contacts within the preceding month should be examined and treated 1
Common Pitfalls and Caveats
- Pruritus may persist for several weeks after successful scabies treatment and is not necessarily a sign of treatment failure 1, 2
- Retreatment for scabies should only be considered if live mites are observed after 14 days 1, 2
- For head lice, the presence of nits alone is not sufficient to diagnose current infestation or justify retreatment 6
- Lindane resistance has been reported in some areas, making permethrin a more reliable option 1, 4
- Both scabies and lice infestations have been associated with secondary bacterial infections, including MRSA 3
Permethrin remains the safest and most effective first-line treatment for both scabies and lice, with excellent safety profiles even in special populations like pregnant women and young children 4, 5, 6.