What is the recommended treatment for head lice (pediculosis capitis)?

Treatment for Head Lice (Pediculosis Capitis)

Permethrin 1% is the recommended first-line treatment for head lice due to its effectiveness and safety profile. 1

First-Line Treatment: Permethrin 1%

Permethrin 1% cream rinse (Nix) is the most studied pediculicide in the United States and offers several advantages:

• Extremely low mammalian toxicity
• Less allergenic than pyrethrins
• Does not cause allergic reactions in patients with plant allergies
• Available over-the-counter
• Leaves a residue designed to kill emerging nymphs

Application Method:

1. Shampoo hair with a non-conditioning shampoo
2. Towel dry hair so it's damp but not wet
3. Apply permethrin to thoroughly saturate the hair and scalp
4. Leave on for 10 minutes (no longer)
5. Rinse with warm water
6. Repeat treatment in 7-10 days (preferably day 9) to kill newly hatched lice 1

Important: Conditioners and silicone-based additives in shampoos can impair permethrin's adherence to the hair shaft and reduce its effectiveness 1

Second-Line Treatment: Malathion 0.5%

If permethrin treatment fails despite correct application, malathion 0.5% lotion (Ovide) should be used for patients 24 months or older 1, 2.

Application Method:

1. Apply to DRY hair in amount sufficient to wet hair and scalp thoroughly
2. Pay particular attention to back of head and neck
3. Allow hair to dry naturally (no heat source, leave uncovered)
4. After 8-12 hours, shampoo hair
5. Rinse and use fine-toothed comb to remove dead lice and eggs
6. Repeat after 7-9 days if lice are still present 2

Caution: Malathion is highly flammable due to high alcohol content and carries risk of respiratory depression if ingested 1

Alternative Treatments

Pyrethrins with Piperonyl Butoxide

• Neurotoxic to lice with low mammalian toxicity
• Applied to dry hair and rinsed after 10 minutes
• Contraindication: Avoid in patients allergic to chrysanthemums
• 20-30% of eggs remain viable after treatment 1

Lindane 1% (Third-Line Option)

• Should be used with extreme caution due to safety concerns
• Several cases of seizures in children have been reported
• Resistance has been reported worldwide 1

Adjunctive Measures

Nit Removal

• Use a fine-toothed nit comb to remove dead lice and eggs
• While not necessary to prevent spreading, nit removal is recommended for aesthetic reasons and to decrease diagnostic confusion
• Vinegar or vinegar-based products applied to hair for 3 minutes before combing can help loosen nits 1

Managing Household Contacts

• All household members should be checked for lice
• Only those with live lice or eggs within 1 cm of the scalp should be treated
• Treat family members who share a bed with the infested person 1

Managing Topical Reactions

• Scalp itching or redness may occur as a response to treatment
• Topical corticosteroids and oral antihistamines may help relieve these symptoms 1

Treatment Failures

When treatment fails, consider:

1. Misdiagnosis
2. Noncompliance with treatment protocol
3. Reinfestation
4. Resistance to the pediculicide 1

If resistance is suspected, switching to a different class of pediculicide (e.g., from permethrin to malathion) is recommended.

Prevention

• Teach children not to share personal items like combs, brushes, and hats
• Promptly treat infested children to minimize spread
• Clean hair care items and bedding belonging to infested persons 1

Remember that head lice infestation is not a health hazard and does not reflect poor hygiene. Children with head lice should not be excluded from school but should be treated promptly to minimize spread.