Treatment for Pubic Lice (Crabs)
Apply permethrin 1% cream rinse to all affected areas and wash off after 10 minutes, or use pyrethrins with piperonyl butoxide applied to affected areas and washed off after 10 minutes. 1
First-Line Treatment Options
You have two equally effective first-line choices 1:
- Permethrin 1% cream rinse: Apply to affected pubic and body hair areas, leave on for exactly 10 minutes, then wash off thoroughly 1, 2
- Pyrethrins with piperonyl butoxide: Apply to affected areas, leave on for 10 minutes, then wash off 1, 3
Both regimens are recommended by the CDC's STD Treatment Guidelines and should be your initial approach 1.
Alternative Treatments for Resistant Cases
If first-line treatment fails (which is increasingly common due to widespread resistance to permethrin and pyrethrins), use these alternatives 1, 4:
- Malathion 0.5% lotion: Apply to affected areas and wash off after 8-12 hours. This is particularly useful when resistance is suspected, though the odor and long application time make it less desirable 1
- Ivermectin 250 μg/kg orally: Take with food (increases bioavailability and epidermal penetration), repeat in 2 weeks because it has limited ovicidal activity and won't kill eggs present at initial treatment 1, 2
Important caveat: Resistance to permethrin and pyrethrins is increasing and widespread, so don't hesitate to move to second-line agents if treatment fails 1, 4.
Special Considerations
Eyelash Involvement
If lice infest the eyelashes, do not apply the standard pediculicides to the eyes 1. Instead, apply occlusive ophthalmic ointment or petroleum jelly to the eyelid margins twice daily for 10 days 1, 5.
Environmental Decontamination
- Machine-wash and dry all bedding and clothing using the heat cycle, or dry clean them 1
- Alternatively, remove items from body contact for at least 72 hours 1
- Fumigation of living areas is not necessary 1
Partner Management
Treat all sexual partners from the previous month, even if asymptomatic 1. Partners should abstain from sexual contact until both parties complete treatment 1.
STD Screening
Always evaluate patients with pubic lice for other sexually transmitted infections, including HIV 1, 3. The presence of pubic lice should prompt a comprehensive STD workup 1.
Follow-Up Protocol
Re-evaluate after 1 week if symptoms persist 1. If you find live lice or observe eggs at the hair-skin junction, retreatment is necessary 1. When one recommended regimen fails, switch to an alternative regimen rather than repeating the same treatment 1.
What NOT to Use
Avoid lindane except as a last resort when all other therapies have failed or cannot be tolerated 1. Lindane can cause seizures and aplastic anemia, should not be used immediately after bathing, and is contraindicated in breastfeeding women and children under 10 years 1.
Common Pitfalls
- Pseudoresistance occurs from poor compliance, incorrect dosing, or reinfestation—ensure patients understand proper application technique and duration 4
- Don't confuse finding nits alone with active infestation; you must visualize live lice to confirm current infection 3, 6
- Remember that modern pubic hair grooming has reduced incidence, but lice can also infest scalp hair, body hair, eyebrows, and eyelashes 4, 7