Permethrin Treatment for Scabies and Lice
For scabies, apply permethrin 5% cream to all areas of the body from the neck down and wash off after 8-14 hours; for head lice, apply permethrin 1% creme rinse to affected areas and wash off after 10 minutes. 1, 2
Scabies Treatment
Permethrin 5% cream is the first-line treatment for scabies and is generally curative with a single application. 3, 2
Application Protocol
- Apply 30 grams (sufficient for average adult) thoroughly from neck to soles of feet 2
- In infants and geriatric patients, also treat the scalp, hairline, neck, temple, and forehead since these areas can be infested 2
- Leave on for 8-14 hours before washing off in shower or bath 3, 2
- One application is typically curative 2
Retreatment Considerations
- Persistent itching after treatment is common and does NOT indicate treatment failure 2
- Only retreat if demonstrable living mites are present after 14 days 2
- If treatment fails, consider alternative regimens such as oral ivermectin 1
Special Populations
- Pregnant and lactating women: Permethrin 5% is the preferred and safe treatment option 1
- Infants as young as 2 months: Can safely use permethrin 5% 3
- Permethrin is superior to lindane and benzyl benzoate, particularly in premature infants, small children, patients with seizures, and pregnant/nursing mothers 4
Head Lice Treatment
Permethrin 1% creme rinse is the first-line pharmacologic treatment for head lice. 5
Application Protocol
- Apply to affected areas and wash off after 10 minutes 3, 1
- Rinse over a sink (not shower/bath) with warm water to limit skin exposure and minimize absorption 3
- Repeat application in 9-10 days if needed 3
Important Caveats
- Diagnosis requires visualization of live lice; nits alone are insufficient 5
- "No-nit" policies for school return are not recommended since nits can remain after successful treatment 5
- Topical itching or burning from inflammation can persist for days after lice are killed and is not a reason for retreatment 3
- Topical corticosteroids and oral antihistamines may relieve persistent symptoms 3
Treatment Resistance
- Permethrin 5% (prescription strength) has been anecdotally recommended for recalcitrant head lice, though lice resistant to 1% permethrin may not respond to higher concentrations 3
- Permethrin 5% is not FDA-approved as a pediculicide 3
Pubic Lice Treatment
Apply permethrin 1% creme rinse to affected areas and wash off after 10 minutes. 3
Special Considerations
- Do NOT apply to eyes 3, 1
- For eyelash infestations: apply occlusive ophthalmic ointment to eyelid margins twice daily for 10 days 3, 1
- Evaluate after 1 week if symptoms persist 3
- Presence of pubic lice should prompt evaluation for other sexually transmitted infections 6, 5
Environmental Measures
Decontaminate bedding and clothing to prevent reinfestation. 3, 1
Decontamination Protocol
- Machine wash and dry using hot cycle, or dry-clean 3, 1
- Alternatively, remove items from body contact for at least 72 hours 3
- For scabies, a 10-minute cycle at 60°C in the dryer kills arthropods 7
- Fumigation of living areas is unnecessary 3
Contact Management
- For lice: Treat sexual partners from the previous month 3, 1
- For scabies: Treat both sexual and close personal/household contacts within the last month 3, 1
- Treatment of close contacts controls outbreaks and prevents repeated infestations 7
Safety Profile
Permethrin has superior safety compared to lindane, with less potential for toxicity and virtually no allergic side effects. 3, 4
- Permethrin is absorbed percutaneously in only small amounts, metabolized rapidly in the skin, and excreted in urine 4
- Lindane carries risks of seizures and aplastic anemia, particularly in children under 2 years, pregnant/lactating women, and those with extensive dermatitis 3
- Lindane is no longer recommended by the American Academy of Pediatrics and is banned in California 3