Head lice

Itching is the most common symptom of head lice. People who have head lice for the first time may not feel itchy right way. It can take 4 to 6 weeks for itching to start.

You may be able to see lice, but they move quickly, avoid lights and are small. You may also see lice eggs on hair shafts. Also called nits, lice eggs stick to hair shafts. They are easiest to see around the ears and hairline of the neck. But they are tiny so it may be easier to see empty nits, especially on darker hair. Empty nits are lighter in color and further from the scalp.

Seeing empty nits doesn't mean there are live lice. That's especially true if the nits are greater than 1/4 to 3/8 inches (6 to 9.5 millimeters) from the scalp.

Sores on the scalp, neck and shoulders are another symptom. Scratching can lead to small bumps that appear red on white skin and may be harder to see on Black or brown skin. These sores may get infected.

Most people who have head lice don't need to contact a healthcare professional. But if you think you or your child has lice, a member of your healthcare team can confirm the presence of head lice and suggest the best treatment.

If you aren't sure if you or your child has head lice, see a healthcare professional. It's easy to mistake other things for nits, including:

• Dandruff.
• Hair products, such as hair spray droplets.
• Beads of dead hair tissue on a hair shaft.
• Scabs, dirt or hair changes from a fungal infection.
• Other small insects that might be in the hair.

Head lice infestation is most often caused by direct contact with these insects. Head lice are a tan or gray insect about the size of a sesame seed. The female louse sticks each egg to the base of a hair shaft less than 1/8 inch (3 millimeters) from the scalp.

The louse life cycle

A louse goes through three stages:

• Eggs, also called nits, that hatch after 7 to 12 days.
• Nymphs, immature forms of lice that become mature adults after about seven days. The nymphs also feed on blood from the scalp.
• Adult lice, which can live for 3 to 4 weeks. The female louse lays up to 10 eggs a day.

Transmission

Head lice crawl, but they can't jump or fly. Head lice most often spread from one person to another by head-to-head contact. This often happens within families or among children who have close contact with each other.

It's less common for head lice to spread without direct contact. But lice may spread from one person to another through items they share if one person is infected. Items include:

• Clothing, such as hats, scarves and sports uniforms.
• Brushes and combs.
• Items worn in the hair, such as headphones, hair clips, headbands and ribbons.
• Pillows, towels, stuffed animals and the fabric that covers furniture.

Household pets, such as dogs and cats, don't spread head lice.

Head lice infect hair of any length and type. Head lice spread mainly by direct head-to-head contact. So the risk of spreading head lice is greatest among children who play or go to school together. In the United States, head lice most often happen in children in preschool through grade school.

When people scratch the itch that head lice cause, the skin may break. The broken skin may get infected.

You can stop the spread of lice by avoiding hair and head contact between people. The chance of spreading head lice from items that come in contact with the hair or head is small. But you can lower your risk of getting head lice by taking some precautions.

• Don't share hair styling tools like brushes, ribbons or clips.
• Don't share hats or scarves.
• Don't encourage hair contact during sports, at playtimes or when kids are together for activities.
• Don't lie on beds, couches or pillows that a person who has head lice has been on recently.
• Don't share fabric items that a person who has had lice has used in the two days before getting treated.

Do use or allow your child to use protective headgear for sports or bicycling. Don't let a fear of head lice stop you from using these important safety items.