Head lice: Diagnosis, treatment, and outcome


Watch this video for dermatologists’ tips to check for and treat lice.

Diagnosing head lice at home

If you are concerned that someone has head lice, you can usually diagnose this at home. You will need 2 common items:

  • Bright light.
  • Fine-tooth comb or lice comb.

What to do: You can find head lice by following these 3 steps:

  1. 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.
  2. Sit the affected child or adult under a bright light.
  3. 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.

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.
                Head lice eggs Head-lice eggs: 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.
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:

First treatment

  • 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 2 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 2 to 3 weeks helps to ensure that you get rid of the lice.

Dermatologists recommend spending most of your energy combing through the hair with the lice comb.

7 to 9 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 7 to 9 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 2 days to wash the hair.
  • Continue to comb through the hair with the lice comb once a day. Do this for 2 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. Medicines that dermatologists prescribe to treat head lice include:

Malathion (mal-uh-THIGH-on) lotion: This is the generic name for a medicine that you will apply to the hair and scalp. It is 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 you must take care to:

  • 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.
  • Leave cigarettes, cigars, and other things that you can smoke in another room. This medicine is very flammable, and smoking while using it can start a fire.
  • Use the medicine ONLY in a room (or other space) free of open flames. Sources of open flames include a lighter, fireplace, stove, and camp fire.
  • 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. 

Benzyl alcohol lotion
: This medicine is approved to treat head lice in people 6 months of age and older. It kills the lice but not their eggs, so retreatment is essential. The most common side effect is irritated skin.

Lindane shampoo: This medicine has been approved by the U.S. Food and Drug Administration (FDA) 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 2 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.

Insecticides can do more harm than good. Never use these to treat a home when someone has head lice.

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 2 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 2 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.

Outcome

Two treatments (spaced 7 to 9 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)

Learn more about head lice

References

Di Stefani A, Hoffman-Wellenhof R, Zalaudek I, et al. “Letters to the editor: Dermoscopy for diagnosis and treatment monitoring of pediculosis capitis.”  J Am Acad Dermatol 2006; 54(5):909-10.

Frankowski BL, Bocchini JA. “Head Lice.” Pediatrics 2010; 126(2):392-403.

Heymann, WR. “Head lice treatments: Searching for the path of least resistance.” J Am Acad Dermatol 2009; 61(2):323-4.

Jones KN, English JC, “Review of Common Therapeutic Options in the United States for the Treatment of Pediculosis Capitis.” CID 2003; 36(1):1355-61.

Ko CJ, Elston DM. “Pediculosis.” J Am Acad Dermatol 2004; 50(1):1-12

Miteva M, Tosti A. “Hair and scalp dermatoscopy.” In Press, J Am Acad Dermatol 10.1016/j.jaad.2012.02.013.

U.S. Food and Drug Administration, “Treating Head Lice.” FDA Consumer Health Information. July 2009.1-2.

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