What are lice?
Lice are tiny wingless insects. They are less than 1/8 inch long (1 to 3 millimeters), or about the size of a sesame seed. They live in hairy parts of the human body. Lice that live in the pubic hairs of the genital area are called pubic lice or crab lice.
Lice bite through the skin to suck blood. Lice attach their eggs, called nits, to hairs. The nits hatch after several days, making more lice.
Lice are not dangerous and don’t spread disease. However, their bites can cause itching and sometimes skin irritation.
How do people get crab lice?
Crab lice can be passed from person to person through close body contact. The lice can live for 1 to 2 weeks away from the body, so you can get lice from things like bed sheets, towels, and sleeping bags if someone infected with crab lice has used them in the last few weeks.
What are the symptoms?
The most common symptom is itching. If there are only a few lice, you may have no symptoms. When there gets to be more lice, the itching may get severe. Sometimes the areas that you have scratched can get infected, so if you think that you might have lice, be sure to get checked.
You may see 1 or more lice or nits in your pubic hair. The nits look like tiny white dots attached to a hair. They look like dandruff, but, unlike dandruff, the nits cannot be brushed or flicked off. They must be pulled off the hair with your fingers.
Crab lice sometimes live in other hairy areas, such as the chest, abdomen, underarms, and head. They may even be in facial hair, such as beards, eyebrows, and eyelashes.
How is it diagnosed?
Your healthcare provider looks for lice or nits in your pubic hairs or on other parts of your body.
How is it treated?
Lice will not go away without proper treatment. Nonprescription anti-lice products, such as Nix rinse or RID shampoo, can be used to kill lice. The shampoo should have 1% permethrin or pyrethrin in it.
Use the anti-lice rinse or shampoo according to the instructions on the package or your provider’s directions. Your provider will probably recommend that you repeat the treatment in 1 week because the nonprescription products kill only crawling lice. They don’t kill unhatched nits. So a second treatment in 7 to 10 days after the first may be needed to kill newly hatched lice.
If a nonprescription product does not kill the lice, you may need a shampoo prescribed by your healthcare provider. Prescription shampoos contain either malathion or lindane to kill the lice. These medicines may have side effects. It is usually better to try one of the safer, nonprescription products first.
- Malathion can sting if your skin is irritated from scratching. It is also flammable, so it is very important to stay away from heat sources or flames for the 8 to 12 hours after you apply it. Don’t use a hair dryer to dry the hair during this time. Let the hair dry naturally.
- Lindane is rarely prescribed because it can cause seizures if it is not used correctly. Also, lindane is not as effective as it used to be because lice are getting resistant to it. Lindane should never be used by small children or women who are pregnant or breastfeeding. Carefully follow your healthcare provider’s directions for its use. Don’t overuse it.
If you are pregnant or breastfeeding, check with your healthcare provider before you use any type of anti-lice product.
Don’t have sex until you have completed the treatment and the lice and nits are all gone.
You need to remove lice from your clothing, towels, and bedding. Machine wash all items that you used in the last 3 days before you started treatment. Use hot water to wash the items. After washing, use the hot setting on your dryer for at least 20 minutes. Anything that can’t be washed this way needs to be dry cleaned. Clothing or other things, like stuffed animals or pillows, that may have lice but cannot be washed or dry cleaned should be sealed in a plastic bag for 2 weeks to kill the nits.
What can be done to help prevent crab lice?
Tell your sexual partner about the crab lice because he or she may also have lice. Since lice can spread easily, everyone in your home should be examined carefully. Anyone who has lice or nits should be treated right away to avoid spreading the lice to others.
The best way to prevent crab lice is to have one sexual partner or avoid sexual contact. Condoms are not good protection against crab lice because condoms don’t cover the hairy areas where the lice live. Also avoid contact with public toilet seats and any clothing or bedding that someone who might have lice has worn or used (unless it has been properly washed).
Developed by David W. Kaplan, MD, and RelayHealth. Published by RelayHealth.
Last modified: 2011-06-30
Last reviewed: 2011-06-09 This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional. References
Pediatric Advisor 2011.4 Index
© 2011 RelayHealth and/or its affiliates. All rights reserved.