Lice, pubic lice (crabs), and scabies are common skin parasites. While they share some traits, their habits on the human body differ, requiring specific treatments. Our experienced pharmacist addresses key questions from Elodie and Alain on these infestations.
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Opt for targeted local treatments for lice. Understanding these parasites ensures the best approach.
Scabies treatments are reserved for lice only as a last resort. If standard local options fail and pediculosis is severe, a doctor may prescribe oral ivermectin, which targets the lice's nervous system—the same medication used for scabies. This is uncommon.
Our pharmacist responds to Elodie, a young mother who discovered lice on her daughter's head.
Elodie: Are there different types of lice?
Pharmacist: Yes, head lice and body lice are distinct species from the same family. Both are hematophagous, feeding on human blood. Infestations are called pediculosis, causing intense itching. Here's where they live and reproduce on the body.
Elodie: So my daughter has head lice?
Pharmacist: Yes, Elodie—it's especially common in children. Head lice (Pediculus humanus capitis) feed from the scalp and grip hair with strong claws. She likely got them from direct hair contact with an infested classmate or shared hat. Check our tips to prevent head lice.
Elodie: Could she also get body lice?
Pharmacist: Possible, but body lice are rarer, often linked to poor living conditions. Body lice (Pediculus humanus corporis) bite skin and live on body hair or clothing fibers, preferring the back, shoulders, groin, and thighs.
Elodie: A friend said my daughter's scratching might be scabies—what is it?
Pharmacist: The scabies mite (Sarcoptes scabiei) burrows into the epidermis to feed and lay eggs, creating tunnels.
Elodie: Does it affect the scalp like head lice?
Pharmacist: No—the wrists, finger webs, buttocks, armpits, navel, elbows, male genitals, and female areolas are most common. It's often a sexually transmitted infection (STI), with severe nighttime itching.
Elodie: How is scabies transmitted?
Pharmacist: Via prolonged close contact; highly contagious forms can spread in communities like nursing homes.
Elodie: What's the best lice treatment?
Pharmacist: Use local lotions for your daughter—they're more concentrated and have longer contact time than shampoos.
Two main types:
A second application 10 days later is essential.
Repeat after 10 days, even if some claim single-use efficacy. Leave on 15 minutes to 8 hours per product. Rinse with mild shampoo, then comb with a fine-toothed anti-lice comb to remove dead lice and nits.
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These related parasites require different treatments.
Our pharmacist advises Alain, who suspects crabs.
Alain: My genitals itch—what are crabs?
Pharmacist: Pubic lice (Pthirus pubis, not Phtirius inguinalis) feed on blood, clinging to pubic hair, anus, body hair, or even eyelashes. They cause itching like other lice.
Alain: I use condoms—can I still get them?
Pharmacist: Yes, phthiriasis is an STI; condoms don't prevent it.
Alain: Should I see a doctor?
Pharmacist: Yes, Alain. Confirm diagnosis and get prescribed lotions with pyrethrins or malathion for pubis and perianal areas. If widespread, treat torso, armpits, thighs, scalp. Asphyxiating lotions aren't recommended. Oral ivermectin is a backup for failures, like for scabies.
FALSE: A persistent myth links these to poor hygiene, but only body lice prefer precarious conditions. Itching and lesions mislead— they're contagious despite good hygiene.
Alain: Treatment ended yesterday, but I'm still itching—restart?
Pharmacist: Post-treatment itching is common for lice, crabs, and scabies—not failure or reinfestation. Doctors can prescribe soothing meds.
Alain: Scratching caused an oozing sore—what now?
Pharmacist: Secondary infections from scratching are typical—not hygiene-related. See a doctor for antibiotics.
Alain: Do they jump?
Pharmacist: No—spread by direct contact or infested linens like bedding, clothes, towels.
