What is the recommended treatment for scabies and lice infestations using Permethrin?

Permethrin Treatment for Scabies and Lice Infestations

For scabies, permethrin 5% cream should be applied to the entire body from neck down and washed off after 8-14 hours, while for lice, permethrin 1% cream rinse should be applied to affected areas and washed off after 10 minutes. 1, 2

Scabies Treatment

First-Line Treatment

• Permethrin 5% cream is the recommended first-line treatment for scabies 1, 2
  • Apply to all areas of the body from the neck down
  • Leave on for 8-14 hours before washing off
  • Approximately 30 grams is sufficient for an average adult 2
  • Safe for use in pregnant women, lactating women, and children 1, 3

Alternative Treatments for Scabies

1. Lindane (1%) - 1 oz of lotion or 30g of cream applied thinly and washed off after 8 hours 1

   • CAUTION: Not recommended for:
     • Pregnant or lactating women
     • Children under 2 years
     • Persons with extensive dermatitis
     • After bathing (increases absorption and toxicity risk)

2. Sulfur (6%) ointment - applied nightly for 3 consecutive nights 1

   • Wash off previous applications before reapplying
   • Wash off 24 hours after the last application

3. Oral ivermectin - 200 μg/kg, repeated in 2 weeks 2

   • Limited ovicidal activity
   • Should be administered with food to increase bioavailability

Special Cases

• Crusted/severe scabies: Consider combination therapy with oral ivermectin and topical permethrin 2
• Immunocompromised patients: Same treatment as immunocompetent individuals 1

Lice Treatment

Pediculosis Pubis (Pubic Lice)

• Permethrin 1% creme rinse 1
  • Apply to affected areas
  • Wash off after 10 minutes
  • Safe for pregnant and lactating women

Alternative Treatments for Lice

1. Pyrethrins with piperonyl butoxide 1

   • Apply to affected areas
   • Wash off after 10 minutes
   • Safe for pregnant and lactating women

2. Lindane 1% shampoo 1

   • Apply for 4 minutes then wash off thoroughly
   • CAUTION: Not recommended for pregnant/lactating women or children under 2

Special Considerations for Lice

• Eyelash infestation: Apply occlusive ophthalmic ointment to eyelid margins twice daily for 10 days 1
• Treatment failures: Re-treat with an alternative regimen 1

Environmental Measures (Essential for Both Conditions)

For Both Scabies and Lice

• Decontaminate bedding and clothing by:
  • Machine washing and drying using hot cycles
  • Dry cleaning
  • OR removing from body contact for at least 72 hours 1, 2
• Fumigation of living areas is unnecessary 1

Contact Management

• Scabies: Treat all household members and close personal contacts within the preceding month, even if asymptomatic 2
• Lice: Treat sex partners from the preceding month 1

Follow-Up and Treatment Failure

When to Re-evaluate

• Evaluate after 1 week if symptoms persist 1
• For scabies, pruritus may persist for up to 2-4 weeks after successful treatment 2, 3

Signs of Treatment Failure

• Living mites still present after treatment
• New burrows or rash appearing after treatment
• Symptoms persisting beyond 2-4 weeks 2

Common Pitfalls to Avoid

1. Inadequate application of medication (not covering all affected areas)
2. Premature washing off of medication
3. Failure to treat all close contacts simultaneously
4. Neglecting environmental decontamination measures
5. Using hair conditioners before permethrin application (reduces effectiveness) 2
6. Misdiagnosing persistent post-scabetic dermatitis as treatment failure

Application Tips

• For scabies, thoroughly massage permethrin cream into skin from neck to soles of feet 2
• For lice, ensure complete coverage of affected hair and skin
• Keep fingernails trimmed to reduce injury from scratching 2
• For improved efficacy in scabies, some evidence suggests applying permethrin as cold cream for two consecutive days 4