To prevent skin irritation, do not repeat insecticide treatment more than 3 times, 1 week apart.
A second treatment is recommended 9 to 10 days after the first treatment to kill any newly hatched lice before they can produce new eggs.
DO NOT over treat. Some louse shampoos can be neurotoxic and overuse can damage the nervous system. Wear gloves when treating more than one person with head louse shampoo. If more than two treatments are required to control an infestation, talk to the School Nurse(s) or the Health Department about alternative methods.
Many lice medicines recommend a second treatment in 9 to 10 days. This will kill any new nymphs that have hatched since the first treatment. Do not treat a person more than 2 times with the same medicine without talking to your doctor.
Generally, if no live crawling insects are seen three weeks after the treatment, it's safe to assume that they are gone. Nits would have hatched by that time if they were alive. Nits and their shells may remain in the hair for some time but won't be viable.
Infestation timeline
So if you look on the scalp and see no visible adult lice and several small nits, it's likely that you've caught lice in the earlier stages and had them for less than 2 weeks. Nits and nymphs: 1.5 to 2 weeks. If you see nits and small, moving lice, you've likely had lice for 1.5 to 2 weeks.
Dry Scalp from Lice Treatment
One of the most common sources of your head still itching after lice treatment is from a dry or irritated scalp from treatment. All over-the-counter lice treatments contain a variety of irritants – from chemicals to salt-based compounds – that cause irritation and drying on the scalp.
It is not usually possible to get rid of lice in one day, as an infestation needs to be treated. However, there are treatments that can help get rid of lice and symptoms caused by lice more quickly. Lice infestations must first be treated by improving the hygiene of the infected person.
If a head lice treatment that you can buy without a prescription fails to work, the CDC recommends that you see a health care provider. Highly effective prescription treatments that you apply to the scalp are available.
Here are some lice facts you need to know: Lice do not spread easily. They also cannot survive more than 24 hours off a human scalp. Lice cannot jump.
Adult lice can't live longer than 24 hours or so on nonhuman surfaces like carpets, hardwood floors, clothing, furniture, sports helmets, headphones, or hair accessories. However, if you have identified lice in your home, isolate and wash those items and areas within at least 72 hours.
Typically, 10–15 head lice are found. The number of lice often depends on personal hygiene, for example, how often the person bathes, shampoos, or changes and washes his/her clothing.
There are two reasons for a recurrent lice infestation: The lice treatment you used didn't work. You or someone in your family came in contact with lice again.
The two treatments 9 days apart are designed to eliminate all live lice, and any lice that may hatch from eggs that were laid after the first treatment.
Do wet combing on days 1, 5, 9 and 13 to catch any newly hatched head lice. Check again that everyone's hair is free of lice on day 17.
Nits are often confused with other things found in the hair such as dandruff, hair spray droplets, and dirt particles. If no live nymphs or adult lice are seen, and the only nits found are more than ¼-inch from the scalp, the infestation is probably old and no longer active and does not need to be treated.
Use heat. Wash any items used or worn by the person in hot water, and dry them on high heat. Lice and nits die when exposed to temperatures higher than 130 F for more than 5 minutes. Wash anything that touched the person's skin or scalp, including jackets, hats, scarves, pillowcases, sheets, and headbands.
Smothering agents: There are several common home products that may kill lice by depriving them of air and smothering them. These products include petroleum jelly (Vaseline), olive oil, butter, or mayonnaise. Any of these products may be applied to the scalp and hair, covered with a shower cap, and left on overnight.
If you do not comb out all the remaining nits, they will hatch and restart the cycle in 7-10 days from that point. That's why we recommend 3 treatments over a 12-day period of time. This stops the life cycle of lice. These are nits at different stages and a louse.
You can treat lice and their eggs with prescription or over-the-counter medicines. After treatment, your skin may still itch for a week or more. This is because of your body's reaction to the lice.
Adults are not immune to head lice. In fact, if you have any close contact with children or even parents of children you can be at risk of catching them if they have them. Lice transfer primarily through head to head contact, so you would have to get close to the other person.
The oval-shaped eggs often look yellow or white but may be the same color as your hair. They are found on the first 1-2 inches of hair shaft closest to the scalp (not the end) and are hard to remove. You may confuse them with dandruff or flakes from hairspray build-up. Head lice nits usually hatch in 8 to 9 days.
Vinegar contains properties that kill and get rid of nits and lice. This mixture should be applied directly to the whole scalp. Mix 1 cup of vinegar with 1 cup of warm water. Next, distribute this mixture onto the scalp and cover your hair with a hair cap.
In the United States, infestation with head lice (Pediculus humanus capitis) is most common among preschool- and elementary school-age children and their household members and caretakers.