Illness & Conditions - Health Conditions
What are lice?
Lice are tiny insects that live on humans and feed on blood. When a large number of lice live and multiply on a person, it is called an infestation.
Three different kinds of lice live on humans:
What causes a lice infestation?
Lice spread easily from one person to another through close contact or through shared clothing or personal items (such as hats or hairbrushes). A louse cannot jump or fly.
What are the symptoms?
The most common symptom of lice is itching. There are different symptoms, depending on which type of lice you have.
Frequent scratching can cause a skin infection. In the most severe cases of head lice, hair may fall out, and the skin may get darker in the areas infested with lice.
How is a lice infestation diagnosed?
A doctor can usually tell if you have lice by looking closely for live lice or eggs in your hair. The doctor may also comb through your hair with a fine-toothed comb to help detect lice. He or she may look at the lice or eggs under a microscope.
Your doctor can also find pubic lice and body lice by looking closely at your body or your clothing.
How is it treated?
Lice won't go away on their own. Be sure to do all you can to treat lice and to prevent the spread of lice.
The most common treatment is an over-the-counter or prescription cream, lotion, or shampoo. You put it on the skin or scalp to kill the lice and eggs. In some cases, you may need treatment a second time to make sure that all the eggs are dead. If two or more treatments don't work, your doctor may prescribe a different medicine.
It's also important to wash clothing and bedding in hot water to help get rid of lice.
Some people continue to have itching for 7 to 10 days after the lice and eggs have been killed. Steroid creams or calamine lotion can relieve the itching. If you have severe itching, you can try antihistamine pills. But don't give antihistamines to your child unless you've checked with the doctor first.
Frequently Asked Questions
Lice are very easily spread, usually through close personal contact. Lice infestation may be caused by any of the three types of lice:
Lice are spread from human to human. Pets don't get head lice and can't spread them to humans.
Itching, the most common symptom of all types of lice infestation, is caused by an allergic reaction . Lice bite the skin to feed on a person's blood. The saliva from these bites causes the allergic reaction and itching.
Itching may not occur right away, depending on a person's sensitivity and history of lice infestation. The first time a person is infested with lice, it may take several weeks or months for itching to start or to be noticed. In a repeat case of lice, a person may begin to itch within 2 days of infestation because the immune system reacts more quickly when exposure has occurred before.
Some people become very sensitive to lice bites and have unbearable itching. Others build up tolerance to the bites and have little or no itching, even with repeated infestations.
In addition to itching, symptoms of lice infestation vary depending on which type of lice is present.
Head lice and their eggs (nits) can be seen on hair , the nape of the neck, and behind the ears. They can vary in color from white to brown to dark gray. The eggs are tiny round or oval shapes that are tightly attached to the hair near the scalp and do not slide up and down on the hair.
Frequent scratching may cause broken skin or sores to form on the scalp. The damaged skin may weep clear fluid or crust over, and it may become infected. In response to infection, the lymph nodes behind the ears and in the neck may become tender and swollen.
A pubic lice infestation may cause itching around the genitals as well as the anus, armpits, eyelashes, and other body areas with hair. Pubic lice bites may cause small, flat, blue-gray marks (maculae cerulea) that look like bruises on the torso, thighs, or upper arms. The marks may last for several months, even after all lice have been killed. Pubic lice, like head lice, can be seen on shafts of hair.
Pubic lice that infest the eyelashes and eyelids may cause irritation and crusting in those areas. The lice may be visible near the base of eyelashes.
Pubic lice tends to be spread by sexual contact. If you or your teen has pubic lice, you may also have some other sexually transmitted infection (STI). Symptoms of STIs can include itching, tingling, burning, or pain of the genitals. For more information about STIs, see the topic Exposure to Sexually Transmitted Infections.
Itchy sores from body lice usually develop in the armpits, around the waist, and along the trunk where seams of clothes press against the skin. The lice and eggs are generally not seen on the skin but may be found in the seams of the person's clothing.
Other conditions, such as dandruff or scabies , can cause symptoms similar to those of a lice infestation.
Lice will not go away without treatment. If the initial treatment does not kill all of the eggs (nits), a follow-up treatment may be required 7 to 10 days later to kill the newly hatched lice. Itching may last for 7 to 10 days even after successful treatment.
After treatment, dead eggs may remain in the person's hair until they are removed. Some schools have a policy of not allowing children to return to school until they are free of eggs.
If your child has lice, report it to your child's day care provider or school so that other children can be checked.
Some children and parents think about or feel lice crawling even after the lice problem is gone. If you or your child feels like symptoms are lasting or feels troubled after the lice problem is gone, talk to your doctor.
Frequent scratching can cause mild complications such as skin infections. In severe cases, hair may fall out. Some people may develop thickened, darkened skin in areas that are infested with lice over a long period.
What Increases Your Risk
Things that increase the risk of getting lice include:
When To Call a Doctor
If you suspect lice infestation (pediculosis), you can try an over-the-counter lice medicine or visit your doctor to double-check your symptoms. Call a doctor if:
Lice will not go away without proper treatment. Even if they don't bother you much, lice can be spread to other household members, sex partners, or other people you have close personal contact with. If you think you have lice, try an over-the-counter lice medicine or call a doctor.
Who to see
If you need help treating a lice problem, contact any of the following:
A pharmacist can answer your questions about medicines that treat lice.
To prepare for your appointment, see the topic Making the Most of Your Appointment.
Exams and Tests
To find out if your child has lice, the doctor will do a close visual exam to look for live lice or their eggs (nits) on the hair . The doctor may also use a fine-toothed comb to help detect lice. He or she may need to look at the lice or eggs under a microscope to confirm the diagnosis.
Lice will not go away without proper treatment. Treatment should begin as soon as symptoms of lice are noticed or when live lice and eggs (nits) are seen on the person's body or in clothing. Specific treatment depends on the type of lice infestation.
Children with head lice can return to school or day care after their first treatment. Some schools have a "no nits" policy in which the child can go back to school or day care only after eggs have been removed. "No nits" policies are discouraged by medical experts. Most doctors agree that a child should be allowed to return to class after proper treatment and should be urged to avoid close head-to-head contact with other students. Confidentiality should be maintained so as not to embarrass a child who has head lice.
Itching may continue even after all lice are destroyed. This happens because of a lingering allergic reaction to their bites. Over-the-counter cortisone ( corticosteroid ) creams or calamine lotion may help. For severe itching, antihistamine medicines (such as Benadryl) or stronger, prescription-strength corticosteroid creams may be needed. Don't give antihistamines to your child unless you've checked with the doctor first. And don't use cortisone cream for longer than 7 days without talking with your doctor. Do not use the cream on children younger than age 2 unless your doctor tells you to. And don't use it in the rectal or vaginal area in children younger than age 12 unless you've checked with the doctor first.
What to think about
Who should be treated?
Treatment is not likely to work if:
Head lice are easily spread among children because kids commonly share hats, combs, and other items. If you or your child has head lice, you can help prevent others from getting it if you avoid head-to-head (hair-to-hair) contact during activities inside the home and outside the home. Also, don't share clothing, bedding, hair brushes and accessories, pillows, stuffed animals, or towels. Frequently examining the scalps of your school-age children may help you discover and treat lice before they spread to the rest of your family. Avoiding prolonged close contact with a person who has lice will also reduce your risk.
Pubic lice are spread primarily among people who have many sex partners. Reducing the number of sex partners you have may help reduce your risk of getting pubic lice.
Body lice may be prevented by bathing regularly and changing clothes daily. Body lice live on clothing, not on the body. Washing clothing in hot water [130°F (54.44°C) or higher] will usually kill adult lice and prevent eggs from hatching. Body lice that are on the skin usually go away on their own with daily bathing and wearing clothes that are not contaminated. Medicines to kill body lice are usually not needed.
To help control the spread of lice, you can also clean combs, brushes, clothing, and other personal items to kill lice and their eggs.
There are both over-the-counter medicines and prescription products to treat head lice and pubic lice. Most products come as a shampoo, creme rinse, or lotion (topical treatment) that is applied to the affected areas, left on for a period of time, and then rinsed off. Doctors sometimes prescribe a pill to treat lice when two or more approved topical medicines have not worked.
If lice infest the eyelashes, your doctor may prescribe an eye ointment for you.
Because body lice live in clothing, not on the body, medicines are generally not needed unless the person is severely infested. The most common way to kill body lice and eggs is to wash clothing and bedding in hot water [130°F (54.5°C) or higher] in a washing machine.
Over-the-counter (OTC) medicines that are recommended for head or pubic lice include: 2
There are other OTC products for lice, but not all of them have good evidence that their benefits outweigh the side effects and other risks. Check the product label . Be sure to follow the directions about proper use and safety. And talk to your doctor or pharmacist about whether these products are safe for young children.
Prescription medicines that are recommended for head or pubic lice include: 2
If these OTC or prescription medicines aren't working, your doctor may prescribe a different medicine to help get rid of lice. These include ivermectin (Sklice or Stromectol), permethrin 5% (Elimite), and spinosad (Natroba). In rare cases, lindane may be prescribed. But lindane is falling out of favor because of the potential for serious nervous system side effects. The American Academy of Pediatrics no longer recommends lindane as a treatment for head lice.
Antihistamines (both prescription and nonprescription) can help relieve the itching that often occurs with lice. These medicines may cause drowsiness. Don't give antihistamines to your child unless you've checked with the doctor first.
If there is a serious skin infection, antibiotics may be needed.
What to think about
It is not necessary to remove lice eggs from hair after treatment with topical medicines, but some people may wish to remove them for cosmetic reasons.
Most products used to treat lice may cause side effects if they are not used properly. Never use a product more than two times (with less than 7 days between uses) without first consulting a doctor.
There is some concern that lice are becoming resistant to (can no longer be killed by) permethrin or other medicine used to treat lice infestations. It is also possible that lice may persist after treatment because the medicine was not used properly or because the person was reinfected by someone else who was still infected with lice.
Wet combing is an option for infants who can't use lice medicines.
Some people try other treatments (such as using petroleum jelly or olive oil to smother lice). But there is not strong evidence that other treatments such as these work well or are safe to treat lice.
Head-shaving helps get rid of head lice. But this method can cause distress to the person whose head is shaved. After cutting or shaving the hair, put the hair into a garbage bag right away and seal it so that lice cannot spread to other areas in your home.
Other Places To Get Help
Last Revised: August 30, 2012
Hill N, et al. (2005). Single blind, randomized, comparative study of the Bug Buster kit and over-the-counter prediculicide treatments against head lice in the United Kingdom. BMJ, 331(7513): 384–387.
Drugs for parasitic infections (2010). Treatment Guidelines From The Medical Letter, 8(Suppl): e1–e20.
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