Head Lice

Diagnosis

Head lice diagnosis involves carefully looking for lice or their eggs (nits) on the scalp and hair. You or a healthcare professional can use a fine-toothed comb, called a nit comb, to check for lice. The comb should be run from the scalp to the end of the hair strand. It is often easier to detect lice on wet hair coated with conditioner or a similar product.

To identify nits, focus on the hairline, especially behind the ears and at the back of the neck. Live nits are typically found close to the scalp, while those more than about 1/4 inch (6 millimeters) away are likely dead or hatched. Using a magnifying glass can help confirm the presence of lice eggs. If unsure, consult a healthcare professional for an accurate diagnosis.

Treatment

Several approaches can effectively kill head lice and their eggs, including medicated treatments, wet combing, smothering, or dehydration methods. Since some treatments do not kill newly laid eggs, a second treatment is often needed 7 to 10 days after the first one to eliminate nymphs. Always follow your healthcare professional’s guidance or product directions carefully.

Medicine available without a prescription
These over-the-counter medicines can be used to treat head lice:

• Permethrin (Nix) or products containing pyrethrin (Rid, Pronto Plus, and others) are suitable for children aged 2 months or older. Apply as directed, then use a nit comb to remove eggs. Repeat treatment in 9 to 10 days and continue combing every few days for 2 to 3 weeks.

• Ivermectin lotion (Sklice) can be used for adults and children 6 months and older. Apply to dry hair once, rinse after 10 minutes, and avoid reapplication unless advised by a healthcare professional.

Possible side effects of topical treatments include mild itching or burning of the scalp that may last for several days.

Prescription medicines
If over-the-counter treatments are ineffective, healthcare professionals may prescribe:

• Spinosad (Natroba): For individuals aged 6 months and older. Apply to dry hair for 10 minutes, rinse with warm water over a sink, and avoid shampooing for 24 to 48 hours. Repeat after seven days if lice persist.

• Malathion: For adults and children 6 years or older. Apply to dry hair and leave for 8 to 12 hours before rinsing. Avoid shampooing for 24 to 48 hours. Repeat after seven days if needed. Since this product is flammable, keep it away from open flames and heat sources.

• Oral Ivermectin (Stromectol): Prescribed when topical treatments fail. It may be given to children over 33 pounds (15 kilograms) and can be repeated after 7 to 10 days if necessary.

Wet combing
Combing wet or conditioned hair with a nit comb can help remove lice and eggs, either as a standalone treatment or alongside medication. Products like conditioner, dimethicone, mayonnaise, or petroleum jelly can slow lice movement, making them easier to comb out.

Avoid using flammable or irritating household products that are not meant for human use.

Smothering agents
Some people use natural substances such as mayonnaise, butter, margarine, or petroleum jelly to block air and suffocate lice. The head is covered with a shower cap overnight after applying a thick layer. However, the effectiveness of these home remedies is uncertain.

Dehydration
Professional lice treatment centers may offer machines that use controlled hot air to kill lice and eggs through dehydration, a method known as desiccation. These machines must be operated by trained professionals.

Do not attempt to use a regular hair dryer for lice removal, as it can blow lice into the air and cause them to spread to others.