Head lice: Diagnosis and treatment
How to treat head lice
Watch this video for dermatologists' tips to check for and treat lice.
Check for and treat head lice like a pro with these dermatologists' tips.
Diagnosing head lice at home
If you are concerned that someone has head lice, you can usually diagnose this at home. You will need two common items:
Fine-tooth comb or lice comb
What to do
You can find head lice by following these three steps:
Wet the hair of the affected child or adult, if possible. Some people think it’s easier to see the lice when the hair is wet. This also prevents the lice from scurrying away.
Sit the affected child or adult under a bright light.
Separate hair into sections. Beginning at the scalp, slowly comb outward through the hair section by section.
What to look for
You are looking for adult lice and their eggs (called nits). You’re more likely to see nits than adults because nits are firmly attached to the hair and do not move.
As you comb through the hair, look closely at the hair behind the ears and around the nape of the neck. These are likely places to find lice and nits.
Before the eggs hatch, you will see color, as shown here on the left. After the eggs hatch, you see a clear shell, as seen on the right.
If the person has adult lice or nits, you will see the following:
Adult lice: These look like one or more light-brown objects that resemble sesame seeds, often moving quickly. You can find these on the scalp or the hair.
Eggs: These are yellow, brown, or tan objects that look like tiny seeds and appear to be cemented to individual hairs close to the scalp. If an egg has hatched, the seed-like object will be clear.
When looking closely at the scalp and hair, it is important to know that kids—and adults—can have all kinds of stuff in their hair. You may see sand, dirt, lint, or dandruff. All of these comb out easily. Nits seem cemented to the hair and very difficult to remove.
Treating head lice at home
There are several products that you can buy at your local drug or grocery store to get rid of head lice and their nits. These are available without a prescription. Dermatologists offer the following tips for using these products:
Carefully read and follow the directions. Using a lice shampoo usually involves lathering a shampoo into the hair and leaving the shampoo on for a few minutes before rinsing.
Apply the product to the head of a fully dressed person, and rinse the product out with a spray hose or running water from a sink. These products are not meant for use while taking a shower or bath. You want to limit the amount of skin that the product touches.
Use only one product. Using two products meant to treat head lice can be harmful. If two different products are necessary, your dermatologist can tell you which ones can be combined.
Use the amount stated on the product. Using more can be harmful.
Use the lice comb that comes with the shampoo. The teeth on a lice comb are closer together than the teeth on a regular comb. Placing the teeth closer together makes it easier to remove the lice and their nits.
Look at the hair 8 to 12 hours after treatment. If the lice seem as active as they were before the treatment, the medicine may not be working. Do not treat again. Talk with your dermatologist. A different lice medicine may be necessary.
The next day
If the medicine seems to be working, you’ll want to:
Wait two days to wash your hair. This lets the medicated product continue to work.
Continue to comb through the hair with the lice comb once a day. Doing this for two to three weeks helps to ensure that you get rid of the lice.
Seven to nine days after the first treatment
Retreat as recommended on the package. Retreatment is generally recommended with all products you can buy without a prescription. Retreatment is usually done seven to nine days after the first treatment. The lice shampoos often are more successful at killing the adult lice than the nits, so retreatment helps to kill any surviving lice that hatched after the first treatment. No approved treatment for head lice can kill all the eggs during the first treatment.
After applying the second treatment, comb through the hair with the lice comb.
Wait two days to wash the hair.
Continue to comb through the hair with the lice comb once a day. Do this for two weeks, checking for lice and nits.
How to improve at-home treatment for head lice
Use a lice comb
Using a lice comb can improve the effectiveness of treatment. It also is important to use a lice comb when school policy requires that a child be “nit free” before returning to school.
If all this seems like too much trouble, another treatment option is to shave the scalp bald.
Treat family and friends
It is very common for close family and friends to get head lice. Dermatologists recommend that you check everyone for head lice. You do not want to treat anyone who does not have head lice; however, you should check everyone every day for 10 to 15 days.
When to see a dermatologist about head lice
If the at-home treatment does not work or this seems more than you can handle, you should see a dermatologist for treatment. Your dermatologist may recommend a product that you can buy without a prescription or a prescription medicine. The Food and Drug Administration (FDA) has approved the following prescription medicines to treat head lice:
Benzyl alcohol lotion: Approved to treat head lice in people 6 months of age and older, this medicine is applied to dry hair. When using this treatment, you want to saturate the scalp and hair. After 10 minutes, it’s time to thoroughly rinse off the medicine. Because benzyl alcohol kills the lice but not their eggs, it’s important to repeat the treatment in seven days.
When using this medicine, you’ll need to comb the hair for nits.
Women who are pregnant or breastfeeding can use this medicine to treat head lice. The most common side effect is irritated skin.
Ivermectin lotion: Approved to treat head lice in people 6 months of age and older, this medicine offers convenience. Invermectin treats most head lice with just one use and without the need to comb nits out of the hair.
Side effects include itchy skin, eye irritation (if the medicine gets in an eye), and a burning sensation on the skin. All are temporary.
Malathion lotion: Approved to treat people ages 6 years of age and older, malathion works by paralyzing and killing the lice and their eggs. This is very potent medicine, so be sure that you:
Keep the medicine away from everyone’s eyes. If the medicine gets in someone’s eyes, flush the eyes right away with lots of water for several minutes.
Do NOT smoke while using this medicine. If anyone in the room smokes while this medicine is being used, a fire can start. Leave cigarettes, cigars, and other things that you can smoke in another room.
Keep the medicine away from flames. You want to use malathion in a room without a stove or fireplace. Because malathion can easily cause a fire, even unlit lighters and camp stoves should NOT be in the room where you’ll use malathion. If you’re using malathion outdoors, be sure a camp fire is NOT burning.
Keep all electrical appliances that produce heat turned off. Using this medicine while a blow dryer, iron, curling iron, or space heater is running nearby can start a fire.
When used as directed, malathion is safe and effective. It can irritate the skin a bit as it works. Some people get dry hair or their skin can burn or sting. These side effects are temporary.
Spinosad suspension: This medicine is approved to treat head lice in people 6 months of age and older. It has been found to be safe and effective when used as directed.
Like Ivermectin lotion:
Most people need to apply this medicine only once
Nit combing is not necessary
You will need to check the scalp seven days after treatment. If crawling lice are seen be sure to tell your dermatologist. You may need to repeat the treatment.
May be prescribed if other treatments fail or cannot be used
Lindane shampoo: This medicine has been approved by the FDA to treat head lice. Approved to treat head lice, this treatment is prescribed when other treatments do not work. It is essential to use lindane shampoo only as directed. It can be toxic when misused.
Treating your home for head lice
Whether you treat at home or see a dermatologist, you must also treat your home. To avoid another infestation, you should clean the following items:
Brushes and combs
Soak combs and brushes that a person with head lice used. Soak these in hot water, 130 degrees Fahrenheit or hotter, for 10 minutes.
Sheets, pillowcases, clothes, blankets, and towels
Place all items that touched the person’s head during the past two days in a washing machine and wash in hot water.
Dry all machine-washed items in a hot dryer, using the hottest setting. Dry for at least 10 minutes.
Stuffed animals and pillows
Place items that cannot be machine washed in a hot dryer and run the dryer on the hottest setting for 20 to 30 minutes.
Other personal items
Hair accessories, helmets, headphones, and other personal items can become infested with head lice. If a person with head lice has touched any of these items during the past two days, you can kill the lice on these objects by:
Sealing the objects in plastic bags
Placing the plastic bags in the freezer overnight or keeping the bags sealed for two weeks
Two weeks is the amount of time needed for adult lice and newly hatched lice to die when hot water, dryer heat, and freezing are impractical.
Furniture, carpets, and floors
Vacuum these thoroughly to pick up any hairs the person with head lice has shed. Everyone normally loses about 50 to 100 hairs a day.
When using prescription treatment for head lice, you still need to wash clothing, towels, and sheets that the person with head lice has used since getting head lice. Wash everything in hot water.
Two treatments (spaced seven to nine days apart) often get rid of head lice. If your child or someone else in your family still has head lice after a few weeks, it means that the treatments did not work or the person got lice again. Make an appointment to see a dermatologist for help getting rid of the head lice. With proper treatment, it is possible to get rid of head lice.
Images of head-lice eggs used with permission of Journal of the American Academy of Dermatology. (J Am Acad Dermatol 2006; 54(5):909-10)
Other images: Getty Images
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