Crabs (pubic lice) and scabies are both itchy, sexually transmissible skin parasites — but they're different organisms with different signs. Crabs are insects that live in coarse pubic hair and leave visible lice or nits you can spot with the naked eye. Scabies is a microscopic mite that burrows into skin, causing intense night-time itching and crooked thread-like lines.
mite; permethrin or ivermectin
treatable; topical
| Item | Value |
|---|---|
| Scabies | curable — mite; permethrin or ivermectin |
| Pubic lice (crabs) | curable — treatable; topical |
The bottom-line difference
The short version: with crabs, you can usually see the parasite or its eggs clinging to your pubic hair. With scabies, you can't — the mite is too small, and what you notice instead is relentless itching (worse at night) and a pimple-like rash with tiny burrows. One lives on the hair; the other lives inside the skin.
Honestly, the itch alone won't tell you which you have — the symptoms overlap enough that most people can't sort it out by feel. A quick look or test is what settles it. If you're not sure, get tested rather than guessing at a treatment.
What each one is
Scabies
Scabies is caused by the human itch mite, Sarcoptes scabiei, which tunnels into the upper layer of skin to live and lay its eggs CDC, About Scabies. It's common worldwide, and in adults it's frequently passed through skin-to-skin contact during sex. Because the mite lives in the skin rather than only in hair, scabies can affect the wrists, between the fingers, the waist, the buttocks, and the penis — not just the groin.
Pubic lice (crabs)
Pubic lice are Pthirus pubis — small blood-feeding insects that grip coarse body hair, mostly in the pubic and perianal region, and sometimes the armpits, chest, beard, or eyelashes CDC, Pubic Lice. Their crab-like shape and habit of clinging to coarse hair are how they earned the nickname. They spread mostly through sexual contact. For a fuller rundown of what they cause, see our guide to crabs symptoms.
Symptoms compared
Both can make the genital area itch, which is exactly why they get confused. The pattern, timing, and what you can see are where they part ways.
Scabies brings intense itching, classically worse at night, along with a pimple-like itchy rash. The giveaway, when it's visible, is the burrow: tiny raised, crooked lines where the mite has tunneled CDC, Scabies signs. After a first infestation, symptoms can take weeks to appear — and a person can spread scabies before they ever feel itchy.
Crabs, by contrast, often cause no symptoms at all. When they do, you'll feel genital itching and may see live lice or nits (eggs) glued to the hair shafts. Heavy scratching can lead to sores or a secondary skin infection CDC DPDx.
How to tell them apart
A few discriminating features do most of the work:
- Can you see it? Crab lice and their nits are visible to the naked eye on pubic hair — a magnifying lens helps. Scabies mites are microscopic; you see the rash and burrows, not the bug.
- Where is it? Crabs stay where coarse hair grows. Scabies often spreads beyond the groin to the finger webs, wrists, waist, and buttocks.
- What's the itch like? Night-dominant, all-over itching points toward scabies. Crab itching tends to stay localized to the hairy areas the lice occupy.
- Burrow vs nit. A thin, crooked raised line in the skin is a scabies burrow. A pale speck cemented onto a hair shaft is a louse nit.
Crabs vs scabies: side-by-side
| Crabs (pubic lice) | Scabies | |
|---|---|---|
| Organism | Pthirus pubis (an insect) | Sarcoptes scabiei (a mite) |
| Where it lives | On coarse hair (pubic, perianal, sometimes chest/eyelashes) | Burrowed inside the upper skin |
| Visible? | Yes — lice and nits seen with the eye or a lens | No — mite is microscopic; you see rash and burrows |
| Hallmark sign | Lice or nits on hair; often no symptoms | Intense night itching; crooked burrow lines |
| Typical sites | Genital/perianal hair | Finger webs, wrists, waist, buttocks, penis |
| First-line treatment | OTC permethrin or pyrethrins lotion/mousse | Prescription permethrin 5% cream or oral ivermectin |
Testing and diagnosis
Crabs are diagnosed simply by finding a louse or nits on hair in the pubic region — they're visible to the naked eye, and a magnifying lens makes it easier. No lab is usually needed.
Scabies is mostly a clinical diagnosis from the burrows, rash, and itching. A clinician can confirm it by examining skin scrapings under a microscope for mites, eggs, or mite feces — but that test is less sensitive than the clinical picture, so a normal scraping doesn't rule scabies out CDC clinical overview.
In practice, a visit is quick — a urine sample, a self-collected swab, or a brief exam depending on what's suspected — and it's often free or low-cost at health departments, Planned Parenthood, and Title X clinics. Because either parasite means recent sexual contact, it's worth screening for other infections too; if you're timing that, check when to test after exposure.
Treatment compared
Crabs respond to an over-the-counter lice treatment — a permethrin lotion or a pyrethrins-with-piperonyl-butoxide mousse — applied to the pubic hair and affected areas, repeated about a week and a half later if live lice remain CDC, Pubic lice treatment. Hot-wash and dry items used in the previous few days. Eyelash infestations are an exception: those are treated with ophthalmic-grade petrolatum, not regular Vaseline, and never with insecticide near the eyes.
Scabies needs a prescription scabicide. The standard is permethrin 5% cream applied over the whole body from the neck down and washed off after the recommended interval; oral ivermectin, dosed by body weight and repeated about two weeks later, is an alternative CDC, Scabies treatment. Two things people miss: treat all sexual, close, and household contacts from the past month at the same time, and decontaminate bedding and clothing (hot machine wash and dry, or seal away from skin for three days). Itching can linger for weeks after the mites are dead, which doesn't mean the treatment failed — see scabies reinfection for how to avoid a true repeat infestation CDC STI Tx Guidelines.
Can you have both at once?
Yes. Crabs and scabies are unrelated parasites, and one doesn't protect you from the other — having both is possible, especially since they share the same route of skin-to-skin and sexual contact. They're also commonly accompanied by other STIs, which is why testing for the rest is reasonable when you find either one. Each has its own treatment, so confirming what you actually have matters.
When to see a clinician
- You can't tell which you have, or treatment hasn't worked — the wrong product won't fix the wrong parasite.
- Itching is severe, spreading, or keeping you awake, or you have widespread rash and burrows.
- You see signs of a secondary skin infection from scratching, like spreading redness, warmth, or pus.
- Lice are on the eyelashes, or you're pregnant, breastfeeding, or treating a young child — these need tailored advice.
- You want to screen for other infections after a new or recent partner — get tested.