Head Lice — Transmission, Diagnosis, & How to Treat

For many kids, head lice is a rite of passage. It can spread through schools and playgrounds like wildfire. But, it’s not just kids who get lice! If your scalp has been feeling extremely itchy all of a sudden, it may be lice. Head lice is a contagious infection with the human head louse. Read on to learn how to diagnose lice, how it is transmitted from person to person, and most importantly, how to treat head lice.

Pediculus humanus capitis

The causative insect in head lice is Pediculus humanus capitis. This is a wingless insect that can only live as a parasite on human heads. They spend their entire lives drinking human blood exclusively. This species of lice do not carry diseases, but if you’ve ever suffered from lice, you know how annoying the itching can be.

Who gets lice?

Everyone gets lice. It doesn’t matter how dirty or clean your hair is. Lice need human blood to survive. They’ll get it from any available host.

how to treat head lice child-with-comb


Lice is more common in schools and places where there is close contact between people. In the United States alone, there are 6-12 million cases of lice per year.

How are lice transmitted?

Lice is transmitted by human to human contact. Like I mentioned before, lice are wingless creatures. They cannot fly or even jump from human to human. The only way to become infected with lice is to come into head to head contact with someone who is already infected.

The lice can also live on objects for short periods of time. Hair combs, towels, hats, and any objects that come into contact with an infected person’s head can be vehicles of transmission.

How to Diagnose Head Lice

Head lice usually present with characteristic symptoms. However, the easiest way to diagnose head lice is to find the live insects or eggs in the scalp of an infected person.



The eggs, also called nits, look like tiny seeds that may be brown, yellow, or clear. The adult lice look like sesame seeds that are able to move.



Symptoms of Head Lice

There are classic symptoms of head lice infestation that make it easy to diagnose. This includes:

• Itchy scalp

• Crawling sensation

• Bugs or lice eggs in the scalp

• Swollen lymph nodes

• Pink eye infection

A person can be infected with head lice and not have an itchy scalp. This is how asymptomatic people can transmit lice before they realize they’re infected.

How to Treat Head Lice

Luckily, the treatment for head lice infestation is simple. There are many different treatment options.

Treating Lice at Home

A special shampoo is used to kill the lice insects. The shampoo should be used at a sink and washed off with minimal contact to the rest of the skin. This means you shouldn’t use a lice-killing shampoo in the shower or bath. Then a special lice comb that has very fine teeth is used to remove the eggs and dead lice.



This process has to be repeated 7-9 days later. No product is guaranteed to kill the lice eggs in one use. Repeating the treatment helps to ensure that all of the lice and their eggs are dead.

The internet also has a plethora of home remedies for treating lice that don’t involve lice killing “chemicals.” I’ve seen everything from apple cider vinegar to Listerine. Attempt at your own risk.

Another treatment option, although often less desirable, is to shave the head bald.

Disinfecting Items That May Harbor Lice

Lice can be transported by anything that comes into contact with the head of an infected person. This means they can live on everyday household objects. Lice can live on an object for up to 2 weeks.

Any combs, brushes, or hair accessories should be soaked in hot water.

All linens like pillowcases, clothes, and towels should be washed in hot water.

Items that cannot be washed such as pillows should be put in the dryer at the hottest setting for 20-30 minutes.

When to See a Dermatologist for Lice

If you’ve tried treating lice at home with over the counter products with no success, it may be time to see a doctor. Lice can sometimes be resistant to some over the counter treatments. There are stronger prescription medications available to treat lice. Some examples of prescription medications to treat lice are benzyl alcohol, ivermectin, spinosad, malathion, and lindane.

Remember that lice are very contagious. Any household contacts should also be checked for head lice. This will avoid someone in the house re-infecting everyone later on.

Complications of Head Lice

Head lice are usually harmless. They do not transmit diseases or cause any long term problems.

However, the incessant itching and need to scratch can lead to breaks in the skin and sores. This can be an entry point for bacteria and secondary infections of the skin.

It’s important to minimize scratching as much as possible.


  1. American Academy of Dermatology. Head Lice. https://www.aad.org/public/diseases/contagious-skin-diseases/head-lice#overview

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