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What is Pubic Lice (Crabs)?
Pubic lice (Pthirus pubis), commonly called 'crabs' due to their appearance, are tiny parasitic insects that live in coarse body hair, primarily pubic hair. They feed on blood and cause intense itching. While less common than historically (possibly due to pubic hair removal trends), pubic lice remain a sexually transmitted infestation. They're different from head lice and require specific treatment.
Symptoms
- Intense itching in pubic area (worse at night)
- Visible lice (1-2mm, greyish-brown) in pubic hair
- Nits (eggs) attached to hair shafts
- Blue-grey spots on skin (from bites)
- Tiny blood spots on underwear
- Itching may take 1-3 weeks to develop after infestation
- Can affect other coarse hair (chest, armpits, beard, eyelashes)
Causes
- Pthirus pubis (pubic louse)
- Close body contact, usually sexual
- Sharing bedding, towels, or clothing (less common)
- Lice cannot jump or fly - require direct contact
- Can survive up to 24 hours away from human body
- Cannot be caught from toilet seats (a myth)
Who Is at Risk?
- Sexually active individuals
- People with multiple sexual partners
- People who share bedding or towels with infested individuals
- All ages and backgrounds can be affected
- Having pubic hair (though can affect any coarse body hair)
Potential Complications
- Secondary bacterial infection from scratching
- Skin irritation and inflammation
- Eyelash infestation (blepharitis) - rare but requires different treatment
- Psychological distress
- Generally no serious medical complications
- Can indicate need for full STI screening
How We Diagnose
Diagnosis is made by identifying live lice or nits (eggs) in pubic or other coarse body hair. A magnifying lens may help. We can distinguish pubic lice from other causes of genital itching such as scabies, dermatitis, or fungal infections. Since pubic lice are sexually transmitted, we recommend a full STI screen.
Treatment Options
Treatment involves insecticidal preparations - permethrin 1% cream rinse or malathion 0.5% lotion applied to all affected areas and washed off after specified time. A second application after 7 days kills newly hatched lice. All bedding and clothing should be washed at 50°C or sealed for 72 hours. Sexual partners need simultaneous treatment.
Prevention
Frequently Asked Questions
Can I catch pubic lice from toilet seats?
No, this is a myth. Pubic lice cannot survive long away from human body warmth and cannot grip smooth surfaces like toilet seats. They require close body contact for transmission, which is why sexual contact is the main route. Sharing towels or bedding is a theoretical but uncommon route.
Are pubic lice the same as head lice?
No, they're different species. Pubic lice (Pthirus pubis) prefer coarse body hair like pubic hair, while head lice (Pediculus humanus capitis) prefer scalp hair. They don't interbreed. However, pubic lice can occasionally infest other coarse hair including beards, chest hair, and eyelashes.
How long do I need to avoid sex after treatment?
Avoid sexual contact until you've completed treatment (including the second application after 7 days) and are confirmed lice-free. All sexual partners from the past month should be treated simultaneously to prevent ping-pong reinfection. After successful treatment, you can resume sexual activity.
Do I need to shave my pubic hair?
Shaving isn't necessary and isn't recommended as sole treatment - nits can be below skin level on hair shafts, and shaving can irritate already itchy skin. Insecticidal treatment kills lice and eggs effectively. However, some people choose to trim hair to make treatment application easier or for psychological reasons.
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Concerned About Pubic Lice (Crabs)?
Book a confidential consultation or STI test at our South Kensington clinic. Walk-in appointments available.



