How to Recognize Crabs

Last Updated: May 3, 2022 References

Crabs, or pubic lice, is transmitted through close, often sexual, contact. It is caused by an insect called “Pthirus pubis” which attacks mainly the pubic hair, but sometimes can be seen in other coarse hairs of the body, such as the legs, mustache and armpits. It is usually transmitted through sexual contact from one person to the other or also after contact with towels, clothing, or bed linens that have been used by a person infested with the lice.^{[1]
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Research source} Luckily, crabs is easily recognizable and completely curable.

Part 1

Part 1 of 3:

Recognizing the Symptoms

1
Pay attention to itching, especially at night. This is the most common symptom of having crabs. It will usually start 5 days after you get exposed to the bug and be isolated within the genital and anal area. It tends to be worse during nighttime hours because this is the time when the lice become more active and feed more often.^{[2]
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Cleveland Clinic
Educational website from one of the world's leading hospitals
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- Fight the urge to itch, as getting lice under your fingernails or on your hands will make the infection more likely to spread. Even if you're not entirely sure crabs may be the culprit, it's better to be safe than sorry.
2
Look for the appearance of dark or bluish spots on the affected area. This will appear once the crabs have bitten the surface of your skin. It indicates that blood has been withdrawn from your skin through biting. Several spots will be seen depending on how many crabs currently infest the pubis area.^{[3]
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- The longer you've had crabs, the more visible these colored spots will become. If left untreated, the area will be covered in all the dark spots the lice have bit.
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3
Spot small white dots in your pubic hair. Crabs do a lot of hair gripping through their claws that will prevent them from falling from the hair. If you look closely you will see eggs attached to the hair and lice crawling over the area.^{[4]
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Cleveland Clinic
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- Of course, it's not just your pubic hair that could be affected, though that's the most common site. If necessary, take a close look at your eyebrows and eyelashes, too, for similar manifestations.
4
Look for visible nits attached to the hairs. Nits are the eggs of the crabs. They look like white, tiny, oval-shaped eggs. They are usually found near the roots or the base of the hair.^{[5]
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- These are just as important to get rid of as the crabs themselves. Once you've started treatment and adult lice aren't visible, nits are what you need to keep an eye on to make sure the infection doesn't return.

Part 2

Part 2 of 3:

Recognizing the Characteristics of Crabs

1
Get out the magnifying glass. Crab lice have similar characteristics to crabs – that is, they have stereotypical claws that are normally associated with ordinary aquatic crabs. However, they're not easily seen due to their size and location. But nevertheless, they still can be seen with ease under a magnifying glass. Can you see the claws?^{[6]
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Centers for Disease Control and Prevention
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- The average louse is about 1 to 2 millimeters in diameter. They are very tiny and just barely visible to the human eye.
- Your dermatologist might use a magnifying glass to diagnose you. It's a surefire way to know exactly what you're dealing with.
2
Look for lice that are whitish-gray or dark brown in color. Lice that haven’t fed on blood yet have this color – but when they have already fed on blood they will turn into a rust-colored or dark brown due to presence of blood in their body.^{[7]
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PubMed Central
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- Crabs feed roughly every 45 minutes. You may notice a change in color in this interval if you monitor them stringently.
3
Know that they can survive 2 days away from your body. In general, crabs live for about 30 days. If they are away from the body, they can survive for 2. That means that even if you're rid of lice (or the people in your household do not currently have lice), it doesn't mean you're home free.^{[8]
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- They love warm areas. If the temperature drops (as in they get removed from the body), they will head for warmer ground. This means you may be able to find them in your sheets or in other dark, stuffy areas.

Part 3

Part 3 of 3:

Understanding Your Condition

1
Treat the area with a specialized lotion or shampoo. As soon as you find out you have crabs, make a trip to your local pharmacy or grocery store for an over-the-counter lice killing lotion or shampoo. If you follow the directions on the label and are diligent, your crabs can easily be gone in no time. It may take a few applications, but it will work.^{[9]
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Trustworthy Source
Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services
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- Along with treating your body, treat your home, too. Wash your sheets, towels, and linens to prevent any lice that may be surviving out in the open from creating a recurring issue. This goes double if you live with others, as crabs are contagious and do not require physical contact for transference.
2
Know that you need to get rid of crabs and their eggs. Crab lice may exist in two forms on your body:^{[10]
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Trustworthy Source
Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services
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- Live lice form (which can be seen crawling on the infected area)
- Egg form (otherwise known as “nits”)
- Finding either form indicates the presence of an infestation which requires immediate treatment. Even just one egg can present a problem.
3
Understand the complications if left untreated. In most cases, there aren’t any serious complications seen with crabs; however, in patients with weak immune systems or other chronic diseases complications may be seen. Because of this (aesthetics and stigma aside), it's important to start treatment as soon as possible.^{[11]
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National Health Service (UK)
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- In cases of infestation that have not been treated for a long period of time, discoloured skin may be seen at the sites where the lice have been constantly biting and feeding from your blood.
4
Watch out for infection. If you already have wounds present near the genital area or you get injured and this is then superimposed with an infestation of crabs, this could lead to a more serious skin infection which could spread around the body through the blood. This type of infection is called a “secondary infection.”^{[12]
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- Pubic lice in the eyelashes or eyebrows gives rise to irritation of the eyes leading to potential cases of conjunctivitis as well as secondary infections of the eye.
5
Treat other areas, like the eyebrows, with a prescription. Special treatment has to be taken for treating crab lice in the eyebrows and eyelashes. Your ophthalmologist will prescribe you with ophthalmic-grade petroleum jelly which must be used on the eyelid margins at least two to five times per day for a period of 7-10 days. This is usually enough to kill the lice effectively.^{[13]
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- Additionally, with care, tweezers may be used to remove any visible lice that may be present within the eyelashes and eyebrows. Regular petroleum jelly (such as Vaseline) must not be used in the eyes as it is an irritant.