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Is Crabs an STD? Diagnosis and Treatment

Lice are small parasitic insects that live on the human body and feed on human blood. Scientists distinguish several species of lice, commonly called head, body, and pubic (“crab”) lice. Each species spreads by crawling—they do not hop or fly—and by human-to-human contact.

Almost everyone has heard about the itchiness and discomfort of head lice, which often infect schoolchildren in their hair, eyebrows, and eyelashes. However, we don’t talk too openly about pubic lice, which spread, most often, through sexual contact and can cause a lot of itchy misery for a person who catches them. A common nickname for a pubic lice infestation is ‘crabs’ due to how these critters look under a microscope.

Are crabs considered an STD? What can you do to protect yourself against the discomfort and embarrassment of catching and spreading crabs?

We’ve written this guide to help you identify pubic lice infestations and protect yourself and your sexual partners from this preventable condition.

Species and Characteristics of Lice

Both head and pubic lice lay eggs (called “nits”) on hair shafts, while the body louse lays eggs in clothing and bedding. The head louse and body louse species are much larger than the tiny pubic louse, and they have distinguishing shapes.

While part of the same family, pubic lice aren’t the same species as head lice. Pubic lice (Pthirus pubis) love coarser hairs. The larger head lice (Pediculus humanus capitis) are much narrower than pubic lice and stick to softer head hair. You can’t get crabs by having head lice move down into different body regions.

While pubic lice primarily live on hairs in the genital area, they may spread to other hairy parts of the body, such as the armpits, legs, beard, eyebrows, eyelashes, or even head hair. What Are Crabs? Pubic lice, aka crabs, are a particular species of louse spread through sexual contact that live in pubic hair, eyelashes, beards, and armpit hair. These insects are obligate parasites, meaning that they need to feed on human blood to survive. Adult lice need to eat every 24-48 hours and will die without a blood feed.

The good news is that, unlike some other parasites that feed on blood, pubic lice don’t carry any bloodborne diseases. Instead, the only symptom you’ll experience from crabs is the itchiness and crawly feeling associated with the lice themselves. If you tend to scratch itchy areas, you may also develop secondary bacterial infections on broken skin from your scratching.

Crabs are one of the most commonly diagnosed STDs that cause itching in the United States. Approximately 3 million Americans get crabs yearly, with an average incidence of 1.3% to 4.6% of the total population. According to the CDC, crabs similarly affect all races and ethnic groups and tend to affect adults more than children.

Interestingly, the global incidence of pubic lice is decreasing yearly. Scientists suspect that current personal grooming trends such as shaving and waxing the pubis are removing the lice’s habitat, preventing them from spreading. By removing their natural habitat, pubic lice are now in danger of becoming an endangered species!

How Can Someone Catch Pubic Lice?

Are crabs an STD?

Crabs are considered an STD because the main transmission method is through sexual contact. The lice will move from one host to another when their pubic hairs are in close proximity and will quickly colonize their new host.

What’s important to note is that you don’t need to have full sexual intercourse to catch crabs. Any activity that brings two rough hairs into close contact with the lice is enough to cause an infestation. Men may even get crabs in their beard after engaging in oral sex with an infected individual.

Are Crabs Only Sexually Transmitted?

While sex is the most common transmission method, there are other ways to catch crabs from an infected person. Sharing towels or clothes with people suffering from a pubic louse infestation can be enough to facilitate spread. Dirty linens may also contain a few nits that can crawl onto a new host during the night.

Pubic lice are happy with any type of coarse hair, including beard and armpit hair. While their preferred habitat is in the pubic area, even sharing a face cloth with an infested person may be enough to transmit the disease.

Common Crabs Transmission Myths

At Rapid STD Testing, we see a lot of people look for excuses for their condition because of the stigma associated with having crabs. A common excuse for getting crabs is that you got it off a toilet seat. This myth is untrue for several reasons, including:

  •       Lice can only survive for a maximum of 48 hours without a meal, meaning that they can’t stay on a surface for a prolonged period of time without dying.
  •       Their legs can’t grasp the smooth surface of a toilet seat, and they’ll get flushed down the toilet sooner than they would latch onto your pubic hair.

Another common myth is that pets can spread pubic lice. Pubic lice are human parasites and can’t survive on pet blood. They rely on human-human body transmission. Dogs and cats have their own types of lice which, in turn, can’t survive on human blood.

Since pubic and head lice are two completely different species, it’s also extremely unlikely that a head louse traveled down to your pubic region and set up in a new territory. Head and body lice have special legs designed for hanging onto smooth hair, while pubic lice can grab onto coarse hair.

Signs and Symptoms of a Crabs Sexual Infection

Pubic lice have an incubation period of around five to seven days after exposure. After this initial stage, you may notice the following symptoms:

  •       Severe itching in the affected area
  •       Blood specks in your underwear
  •       Red or blue spots around the affected area of skin
  •       Rash
  •       Fatigue
  •       Low fever

The reason for the relatively long incubation period is that you’ll only pick up a few adult lice from your partner. These lice need to go through one or more reproductive cycles to build up their numbers. Once they start biting in earnest, you’ll start developing an allergic reaction and noticing their presence.

Both adult pubic lice and their nits are visible to the naked eye. They’re relatively small, around 2mm when fully grown, so you may need a magnifying glass to confirm their presence.

Nits, or lice eggs, are oval and yellowish-white. They usually sit towards the root of the hair shaft and can be difficult to detect if you don’t know what you’re looking for.

Recently-hatched “nymphs” are transparent and smaller than adult lice. Adult lice come in an array of colors, ranging from grayish-white to tan or copper. They tend to get darker if they’ve recently fed and may blend in with your skin tone, so you may need to look closely to find them—or use a test from Rapid STD Testing to confirm their presence.

Finding pubic lice may be a challenge since they tend to accumulate close to the body where it’s warmer. They can often move down into the bottom reaches of the pubic area, where detecting them is extremely tricky.

Pubic lice don’t carry bloodborne diseases, which means that getting crabs may be annoying and frustrating but is unlikely to cause severe long-term health issues. Any symptoms associated with a pubic lice infestation result from the body’s allergic reaction to the bites. The moment you remove the lice, the symptoms will soon cease.

Diagnosing Pubic Lice Infestations

Since lice are very good at hiding, it may be a good idea to get a rapid STD test to confirm your suspicions. Generally, a healthcare provider will use visual identification, but they may also send a sample to the lab for further identification.

Getting pubic lice isn’t a sign of having unsafe sex, but healthcare practitioners may recommend a 10-panel STD test if they diagnose pubic lice in a patient. These tests will also check for other common STDs that can often manifest with similar symptoms to lice, such as itching and rashes.

Once the healthcare professional confirms their diagnosis, you should tell recent sex partners and people with whom you’ve shared a bed, clothes, or towels about the condition. These people should get tested for lice as well as soon as possible to prevent further spread. While it’s an awkward conversation to have, the sooner everyone gets the necessary treatment, the better.

Pubic Lice Prevention and Treatment

Luckily, crabs are one of the more easily curable STDs that also cause the fewest long-term health concerns.


Ideally, you want to prevent catching any STD, including crabs. The challenge with pubic lice is that common STD prevention methods, like condoms, don’t stop the spread of crabs. Condoms don’t cover the entire genital area, which means that you’ll still get the hair contact needed to transmit the STD.

There are three main ways to prevent or limit the spread of crabs:

  •       Complete abstinence, including abstinence from oral intercourse
  •       Sex with partners whom you know to be disease-free and who will remain so. Monogamous partners are significantly less likely to transmit an STD. If you do have non-monogamous partners, try to have regular same-day STD testing to ensure that both of you are STD-free.
  •       Shaving or body hair removal. Having a clean-shaven groin area can reduce the chances of transmitting the disease. However, if you already have crabs, shaving isn’t an effective treatment option since the lice can jump to other coarse hairs in the vicinity and eventually move up to your armpits and eyebrows.


If you have a confirmed pubic lice diagnosis, you’ll be relieved to know that treatment options are extremely simple and effective. Taking a few additional precautions can also help prevent their recurrence and keep you crab-free.

The most common treatment is a lotion or shampoo. Make sure to follow the instructions for best results and to ensure that you eliminate all lice from your body. Here are some general guidelines for pubic lice treatment:

  •       Check your entire body, including underarms, beard, and eyebrows, for lice.
  •       Apply the lotion or shampoo to all the affected areas and other hairy spots, just in case.
  •       Leave the treatment for the allotted time given in the instructions.
  •       Wash off with warm water.
  •       Look for nits and remove them using a fine-tooth comb.
  •       Wash your linens, clothes, and towels using the hot water cycle. The heat will kill off any parasites trying to hide. If you have items you can’t wash, put them in a sealed bag and don’t touch them for a couple of weeks.
  •       Pause your sex life.
  •       Repeat as necessary until you’re clear of lice.

Send the Crabs STD Packing with Testing and Treatment

Knowing that you have crabs is the first step towards getting rid of them. Get in touch with Rapid STD Testing for discreet, efficient testing that will get you on the road to recovery.