Lice are crab shaped parasites with six legs and claws, about the size of a sesame seed. They move by crawling and cannot hop or fly. There are three varieties of parasitic insects (lice): head, body, and pubic lice. In order for lice to survive, they must feed on blood within 24 hours. If a louse falls off a person and can’t feed, it will die in 1-2 days. The adult female lays 5-6 eggs (nits) per day which are attached to individual hairs. The young hatch 7-10 days later. The louse will reach maturity in approximately two weeks. The adult female lives 20 to 30 days and is capable of laying 50-100 eggs during her lifetime.
Pubic Lice (Crabs)
“Crabs” (Pubic) lice are most frequently spread by sexual contact; however, transmission through infested materials, such as bedding, and towels, is possible yet infrequent.
Although more commonly found in the pubic hair, these lice may also be located in the underarm area, on the chest, eyelashes, even in mustaches and beards. Pubic lice are often the size and color of small freckles. When severe itching occurs in the genital area, investigate the possibility of crabs. Diagnosis should be confirmed by a health care provider if you are unsure about infestation.
A common misconception is that pubic lice can be easily spread by sitting on toilet seats. Lice can only crawl and cannot hang onto smooth surfaces like a toilet seat. Pets cannot spread lice either.
Body and Head Lice
These two species of lice live on hairs located on the body and head. The female deposits the nits, or eggs, at the base of the hairs.
Body, and head lice are spread by:
- Direct contact with an infested person or stray hairs that have nits.
- Personal items – combs, brushes and hair care items as well as towels and pillowcases.
- Clothing, including hats, ribbons and other head coverings may also spread body and head lice.
Treatment of All Lice Types
A 1% Permethrin lotion is recommended to treat pubic, body and head lice. It is available without a prescription at a pharmacy. Apply the medication exactly as directed. A prescription lotion is available, as well as an oral medication (Ivermectin), in case of treatment failure.
All persons with symptoms, especially bedmates and household contacts, should be treated at the same time.
- Wash the infested area; towel dry.
- Thoroughly saturate hair with lice medication. If using Permethrin or Pyrethrin, leave medication on for 10 minutes. Thoroughly rinse off medication with water. Dry off with clean towel.
- Following treatment, most nits will still be attached to hair shafts. Nits may be removed with fingernails, or with a special fine-toothed comb. It is important to mechanically remove all nits for treatment to be effective.
- Put on clean underwear and clothing after treatment.
- If a few live lice are still found 8–12 hours after treatment, but are moving more slowly than before, do not retreat. The medicine may take longer to kill all the lice. Comb dead and any remaining live lice out of the hair using a fine–toothed nit comb.
- If, after 8–12 hours of treatment, no dead lice are found and lice seem as active as before, the medicine may not be working. Do not retreat until speaking with your health care provider; a different pediculicide may be necessary. If your health care provider recommends a different pediculicide, carefully follow the treatment instructions contained in the box or printed on the label.
- To kill any lice and nits that may be left on clothing or bedding, machine wash those washable items that the infested person used during the 2-3 days before the treatment. Use the hot water cycle (130 degrees F) of the washing machine to wash these items. Use the hot cycle of the dryer for at least 20 minutes. Adult lice will die after 24 hours without human contact. Any eggs left by the female lice will hatch within two weeks and die within a few hours without food.
- Disinfect combs, brushes and similar items by washing with the medicated shampoo, or in hot water (130 degrees) for 5-10 minutes.
- Items which cannot be washed or dry-cleaned can be isolated for two weeks sealed in a plastic bag.
- All rooms and furniture used by infected persons should be vacuumed. Do NOT use fumigant sprays, which can be harmful and are not needed.
- Inform any sexual partners that they are at risk for infestation.
- Avoid any sexual contact until partners have been treated and infestation has been cured. Testing for other sexually transmitted infections is recommended.
- Re-treat in 7-10 days if lice are still found.
Treating Nits and Lice Found on Eyebrows or Eyelashes
If only a few nits are found, it may be possible to remove live lice and nits with your fingernails or a nit comb.
If additional treatment is needed for pubic lice nits found on eyelashes, applying an Ophthalmic-grade petrolatum ointment (only available by prescription) to eyelids twice a day for 10 days is effective. Vaseline is a type of petrolatum, but is likely to irritate the eyes if applied.
DO NOT share combs or hair brushes.