Head lice are a type of parasitic insect that live on the scalp and hair. People can use over-the-counter (OTC) or prescription medication to treat a head lice infestation.

Head lice are small insects that live on the head and consume blood from the scalp, which can cause an itching sensation. Adult head lice have six legs and are usually grayish-white or tan. Other types of lice can live elsewhere on the body, including body and pubic lice.

While head lice are neither dangerous nor a sign of poor hygiene, they can transmit very easily and cause uncomfortable itching. People can apply medication to their scalp to kill lice and their eggs.

This article discusses which medications can help treat head lice.

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A doctor may suggest products commonly available in most pharmacies as a first-line treatment for head lice. Some medications may also have an ovicidal effect, meaning they also kill lice eggs. They are available in a variety of strengths and formulations.

Initially, a doctor will usually recommend OTC products, such as a shampoo. If ineffective, a doctor may prescribe stronger medications.

OTC lice treatments

A doctor may suggest products commonly available in most pharmacies as a first-line treatment for head lice. Typically, the active ingredients in these products are chemicals such as pyrethrum or permethrin. These ingredients are a pesticide — a chemical toxic to insects — known as pyrethrin. These chemicals occur naturally but can also be synthetic. Pyrethrin interferes with a lice’s nervous system to kill them.

People will need to follow the instructions on the packaging. Typically, a person applies these products to the scalp, either as a shampoo or after shampooing their hair. After leaving the product on for roughly 10 minutes, they can thoroughly rinse their hair with warm water.

Prescription lice treatments

If OTC products do not work or infestations repeatedly occur, a doctor may suggest prescription treatments. Some examples of prescription lice treatments include:

  • Ivermectin: This medication is a semi-synthetic antibiotic that also disrupts the nervous systems of lice. The lotion version of this medication requires applying the product to dry hair and scalp. After waiting 10 minutes, a person rinses out the product using only water.
  • Malathion: Similarly, malathion also affects a chemical in the nervous system of lice. Also available as a lotion, a person will need to apply enough product to dry air to thoroughly wet the hair and scalp. A person can then allow hair to dry naturally, then shampoo the hair after 8–12 hours.
  • Abametapir: This chemical is a metalloproteinase inhibitor. This enzyme is critical for egg hatching and the survival of head lice. Therefore, targeting this enzyme can help kill head lice. This treatment requires a person to apply and massage the product onto dry hair and scalp and leave for 10 minutes. They can then rinse off the product with warm water.
  • Spinosad: This option also targets the nervous system of lice. It can lead to increased activity levels, which may paralyze and kill lice. A person can apply the suspension to dry hair and scalp, leave for 10 minutes, then thoroughly rinse it off with warm water.

It is also worth noting that medications may take up to 12 hours to be effective. While some options may require retreatment to kill lice, a person can check with their healthcare professional before reapplying the medication.

In addition to using pediculicide medication, the Centers for Disease Control and Prevention (CDC) add that people can try the following to treat head lice:

  • using a fine-toothed comb to help remove lice
  • soaking combs and brushes in hot water
  • machine washing and drying items such as hats, pillowcases, bedding, clothing, and towels at a high temperature
  • sealing items in a plastic bag for 2 weeks if they are unable to wash them
  • not sharing items such as hats, grooming aids, and towels
  • vacuuming furniture and floors to remove hairs that may contain lice

Some anecdotal evidence suggests that certain essential oils can also help treat head lice. For example, proponents indicate that tea tree oil is beneficial against head lice. However, more research is necessary to investigate their effectiveness.

Learn more about natural remedies for head lice.

Health experts recommend the following tips to help prevent and manage the spread of head lice:

  • avoiding head-to-head contact
  • not sharing clothing that comes into contact with hair, such as hats
  • not sharing combs, brushes, or towels
  • disinfecting combs and brushes in hot water if a person with a lice infestation uses them
  • not laying on beds, couches, pillows, carpets, or stuffed animals that have been in contact with a person with a lice infestation
  • machine washing and drying clothing, bed linens, or other items that have been in contact with a person with an infestation
  • vacuuming the floor and furniture
  • not using fumigation sprays or fogs, which can be toxic to humans

According to the CDC, the following signs and symptoms may indicate a head lice infestation:

  • itching on the scalp due to an allergic reaction from head louse bites
  • tickling sensation, or feeling that something is moving in the hair
  • irritability and difficulty sleeping, as lice are more active in the dark
  • sores on the head from scratching, which are at risk of infection from bacteria on a person’s skin

While head lice are not harmful, they are highly transmissible and can cause uncomfortable itching. If a person notices symptoms of lice, they should seek treatment.

OTC medications are often effective. A person typically applies the medication to their scalp to kill insects. If unsuccessful, a person should contact their doctor, who may prescribe stronger medications to treat head lice.