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.
After each treatment, checking the hair and combing with a nit comb to remove nits and lice every 2–3 days may decrease the chance of self–reinfestation. Continue to check for 2–3 weeks to be sure all lice and nits are gone.
Head lice eggs (nits) cannot hatch and usually die within a week if they do not remain under ideal conditions of heat and humidity similar to those found close to the human scalp.
But unfortunately, the nits will not simply fall out your hair. The lice themselves take 7 to 11 days to hatch, so after that what is attached to the hair is the empty eggshell or the dead nit. These will stay attached to the hair and as the hair grows you will find them further and further down the hair shaft.
Can someone have nits but no lice? 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.
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.
New eggs are attached to the hair shaft very close to the scalp. Eggs that still contain a louse embryo are brownish in color, while the empty egg shells are white to grey.
What does a dead lice egg look like? A dead lice egg will be white or grey. As they are empty, they will be flat and dry.
Coconut, tea tree oil, lavender, eucalyptus, rosemary, lemon grass, and peppermint are scents popularly believed to repel lice. Using any coconut scented shampoo and conditioner is an easy way to increase your defense. At 1% concentration, tea tree oil killed 100% of head lice after 30 minutes.
The life cycle of the head louse has three stages: egg, nymph, and adult.
Most treated nits (lice eggs) are dead after the first treatment with Nix. The others will be killed with the 2nd treatment. Removing the dead nits is not essential or urgent. However, it prevents others from thinking your child still has untreated lice.
Lice lay their eggs (called nits) on the hair shaft itself. Nits adhere to your hair and will not flake off like dandruff does.
After Treating with Lice Medicine
Check for lice again in 8 to 12 hours. Use the nit comb to remove dead lice and nits. If some are still present but moving slowly, do not shampoo again. If lice are still active and no dead lice are found, call your health care provider.
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.
You do not need to use regular shampoo or conditioner after the lice treatment. In fact, it is best to not shampoo again for 2 days, in order to give the medicine time to work. The medicine will kill the live lice bugs, generally within 12 hours.
Repeat treatment every day or every other day for 2 weeks. Some lice eggs (nits) survive head lice treatments. The only way to be sure that lice won't come back is to pick out all nits. Nits left on the hair can hatch and cause a new case of head lice.
Lice eggs (nits).
These look like tiny yellow, tan, or brown dots before they hatch. 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.
If nits are yellow, tan, or brown, it means the lice haven't hatched yet. If the nits are white or clear, the lice have hatched and just the egg remains. Lice eggs hatch within 1 to 2 weeks after they're laid.
Detection combing can be carried out on dry or wet hair. Dry combing takes less time, but wet combing is more accurate because washing with conditioner stops head lice from moving.
The lice might have been removed but not all the nits and 3 to 4 weeks later those nits have hatched and matured. To break this cycle you have to keep clearing both the nits as well as the lice out of the hair, day after day. If not, the nits hatch, mature, mate, they lay eggs, those eggs mature, hatch and so on.