For years, parents have been buying these non-prescription shampoos and cream rinses. Because the active ingredients have remained the same all these years, new generations of head lice have become immune to them. Once lice become immune, the product no longer works. Scientists call this resistance.
Insecticide resistance is common, so you need to check that the lice you comb out are dead. If the insecticide has worked, the lice will be dead within 20 minutes. If the lice are not dead, the treatment has not worked and the lice are resistant to the product and all products containing the same active compound.
Finding eggs (nits) without lice does not necessarily mean that there is an active infestation; nits can be found for months after lice are treated. Because lice lay eggs at the base of the hair shaft, the identification of nits within ¼ inch of the scalp suggests (but does not confirm) an active infestation.
Head lice can become resistant to the insecticide malathion. So, if malathion hasn't worked for you, you should try either a physical insecticide or wet combing. It's important to check everyone in the household for head lice again at the same time – and treat them if you find any live lice.
You may be wondering: why won't my lice go away? Head lice keep recurring when eggs are missed and left in the hair. Those missed eggs then hatch and you find head lice again. Removing all the eggs is key to stopping head lie recurring.
Lice treatment shampoos (called pediculicides) are available over the counter or with a prescription. If you're pregnant or breastfeeding, ask your doctor to recommend a product that's safe to use. Both over-the-counter (OTC) products and prescription treatments may kill live lice and their eggs (nits).
Can a head lice infestation be cured? Yes, but this is not always easy as some lice are now resistant to the insecticides used to treat them, and repeated infestations are common.
As with furniture and carpets, adult lice typically live for around 2 days on pillows and sheets without human contact. Nits will not hatch and will die within a week. People should machine wash any pillows or sheets someone with lice has used in hot water of more than 130°F (54.4°C) .
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.
Don't Obsess Over Nits
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.
Tea Tree Oil. Though many people are sensitive to tea tree oil, it has been shown to be effective at killing lice. One study showed a 100% mortality rate after 30 minutes of treatment. A tea tree oil-scented spray or shampoo may be useful in preventing reinfestation.
They are empty eggshells and stick strongly to hair. They will eventually fall out.
It may not remove all nits, especially those further down the hair shaft or close to the scalp. Additionally, if any lice or nits are left behind on bedding, clothing, or furniture, they can quickly reinfest a shaven scalp once the hair starts to grow back.
You should treat again only if there are live (crawling) lice several days after treatment. Treat again after all eggs (nits) have hatched but before new eggs are produced. If your medication kills lice but does not kill eggs, treat again about a week after the first treatment (7 – 9 days depending on the drug).
Spinosad (Natroba).
Spinosad is approved for adults and children age 6 months and older. It can be applied to dry hair and rinsed with warm water after 10 minutes. It kills lice and nits and usually doesn't need repeated treatment.
It may be possible to have nits but no lice. If a person cannot find any nymphs or adult lice in the scalp and the nits are more than a quarter of an inch from the scalp, these may be dead and from an old infestation. However, the lice could be in hiding.
They are very small and will be a dark golden-brown colour if they are about to hatch or are white if the louse has already hatched and left the egg. If they are full then they will be plump and shiny. What does a dead lice egg look like? A dead lice egg will be white or grey.
Any nits that fall off the head will not hatch or reattach.
Head lice are only found on the human head or hair. Head lice do not live on furniture, hats, bedding, carpet or anywhere else in the environment. Treating anything other than the human head does not eradicate head lice.
Lice lay nits on hair shafts close to the scalp, where the temperature is perfect for keeping warm until they hatch. Nits look a bit like dandruff, but aren't removed by brushing or shaking them off. Unless a child has many head lice, it's more common to see nits in the hair than live lice crawling on the scalp.
What makes someone contagious with head lice is having a mature, egg-laying adult female louse on your head that could travel to another head. After the first treatment, when the egg-laying lice are eliminated, you are no longer contagious.