Head lice

What is head lice?

The head louse, Pediculus humanus capitis, is a parasitic insect only found on humans that feeds on human blood several times a day. They are found on the head near the scalp, in eyebrows and/or eyelashes. They are not known to cause disease but can result in itching that could lead to a secondary infection from scratching. Lice do not fly or jump and are spread by crawling from direct head to head contact with an infested person (e.g. selfies, sharing beds or pillows). Spread by sharing personal items is uncommon (e.g. hats, coats, scarves, combs, brushes, towels) unless these items contain hair that has been recently shed (1-2 days) by an infested person or a louse has just crawled on the item. Personal hygiene has nothing to do with contracting head lice.

Head lice have three forms:

Stage 1 is the egg, called nit, laid by the female louse and found near the base of the hair shaft. They are nearly cemented to the hair follicle, appear yellow or white, and are only about the size of a knot in a piece of thread. Nits usually take about 8-9 days to hatch.

Stage 2 is the nymph, which is what comes from the hatched egg. They must feed on human blood and will mature into adults in about 9-12 days.

Stage 3, the adult louse, is about the size of a sesame seed and can live about 30 days if feeding on human blood. If it falls off, it will die within 2 days. Adults have 6 legs, are grayish-white in color, and females can lay about 6 eggs per day.

Signs and Symptoms:

  • Itching or tickling sensation that something is crawling. May be worse at night.
  • Difficulty sleeping
  • Sores on scalp from scratching. Sore may become infected.


Most infestations can be safely treated at home with over the counter (OTC) head lice medications. OTC medications are a form of insecticide that kill the crawling louse only and will need to be repeated in 9 days to kill the newly hatched nits. Use the treatments strictly as directed and avoid contact with the eyes. Speak with the pharmacist if you are unsure which product to buy or need instructions for use. Treatment kits will contain a nit comb and instructions on how to remove nits from the hair.

If you have a reaction to the OTC medications or if they are not working to kill the lice, schedule an appointment with a provider for assessment and treatment. Prescription medications are available if needed. Do not use medications more frequently than instructed as they can be dangerous if misused or overused. If you have used the medications twice without a cure, follow up with a provider as soon as possible. Do not combine treatments unless instructed by your doctor or pharmacist.


  • Avoid direct hair to hair contact with any infested person
  • Avoid use of items that may have come into contact with an infested person (hats, brushes, scarves, bedding, pillows, hair bows, clothing, etc.)
  • Machine wash bedding, clothing, and other items in hot water and dry on high heat setting. Items that cannot be machine washed, can be dry cleaned or sealed in a plastic bag for up to 2 weeks to kill lice.
  • Disinfect combs and brushes by soaking in hot water (at least 130 degrees) for 5-10 minutes.
  • Vacuum rugs or furniture where an infested person may have sat or reclined within the last 2 days