Yes, permethrin is an effective and widely used treatment specifically designed to kill head lice. It is one of the most common over-the-counter options for treating head lice infestations.
Permethrin is a synthetic pyrethroid, a class of insecticides that are chemically similar to naturally occurring pyrethrins found in chrysanthemum flowers. It works by disrupting the nervous system of insects, leading to paralysis and death. When applied to the hair and scalp, permethrin effectively targets and eliminates live head lice.
How Permethrin Works Against Lice
- Kills Live Lice: Permethrin's primary action is to kill adult lice and nymphs (young lice) that are actively infesting the scalp and hair.
- Residual Effect: An advantage of permethrin is its residual activity; it can continue to kill newly hatched lice for several days after the initial application. This helps to address any lice that emerge from eggs shortly after treatment.
- Does Not Kill Unhatched Eggs (Nits): A crucial point to understand is that permethrin does not effectively kill unhatched lice eggs, commonly known as nits. Nits have a protective outer casing that permethrin cannot penetrate.
Why a Second Treatment is Often Necessary
Because permethrin does not kill nits, a single application may not completely eradicate a lice infestation. Nits can hatch days after the initial treatment. To ensure all lice are eliminated, including those that hatch after the first application and before they mature and lay new eggs, a second treatment is usually recommended.
A common treatment schedule involves applying permethrin twice:
| Treatment Phase | Timing | Purpose |
|---|---|---|
| First Treatment | Initial application | Kills live lice present on the scalp and hair. |
| Second Treatment | Around day nine | Kills any newly hatched lice before they can produce new eggs. |
This two-step approach is vital for breaking the lice life cycle and preventing a recurrence of the infestation from previously unhatched eggs.
Important Considerations When Using Permethrin
- Always strictly follow the specific instructions provided on the permethrin product packaging.
- Apply the treatment to dry or damp hair as directed by the product instructions.
- Leave the product on for the recommended duration before rinsing thoroughly.
- After treatment, it is highly recommended to comb through the hair with a fine-toothed nit comb to remove dead lice and any remaining nits.
- If a lice infestation persists despite proper treatment, or if you have any concerns, consult a healthcare professional.
For more comprehensive information on head lice and their management, you can visit the Centers for Disease Control and Prevention (CDC) website.
