Lice eggs (nits) are stubbornly glued to individual hair strands, and most lice treatments don’t kill them reliably. The single most effective way to get rid of them is physical removal with a fine-toothed metal nit comb on wet, conditioned hair, repeated daily until no viable eggs remain. This matters because eggs hatch in 6 to 9 days, so any eggs left behind can restart an infestation even after you’ve killed every adult louse.
Why Lice Eggs Are So Hard to Remove
Female lice cement each egg to the hair shaft with a glue-like substance that doesn’t dissolve in water, regular shampoo, or most over-the-counter lice treatments. The egg itself has a hard shell that protects the developing louse inside from chemicals and environmental exposure. This is why simply treating with a medicated shampoo and hoping for the best rarely works. The treatment may kill crawling lice, but the eggs often survive and hatch days later.
Eggs are tiny, about the size of a sesame seed, and can be white, yellowish, or tan. They’re most commonly found near the scalp behind the ears and along the neckline, where body heat keeps them warm enough to develop. A single female louse can lay several eggs per day, so even a small infestation can leave dozens of nits scattered through the hair.
How to Tell Live Eggs From Empty Shells
Not every nit you find is a threat. Eggs found more than a quarter inch from the scalp are generally either already hatched (empty casings) or dead, because they’ve moved too far from the warmth they need to develop. These empty shells can cling to hair for weeks or even months after an infestation is over, which is one reason misdiagnosis during nit checks is extremely common.
Live, viable eggs sit close to the scalp, within about a quarter inch. They tend to look plump and darker in color. If you pop one between your fingernails and it makes a small snap, it was viable. Empty casings look more translucent or white and feel flat. Focus your removal efforts on the eggs closest to the scalp, since those are the ones that can still hatch.
Wet Combing: The Most Reliable Method
Wet combing with a metal nit comb is the cornerstone of egg removal, and no chemical treatment replaces it. Here’s how to do it effectively:
- Use a metal nit comb. Plastic combs that come in lice treatment kits have teeth that are too flexible and spaced too far apart. A purpose-built metal nit comb has rigid, tightly spaced teeth that catch eggs as they slide down the hair shaft.
- Work on wet, heavily conditioned hair. Saturate the hair with a thick conditioner. This lubricates the strands so the comb glides through more easily, and it immobilizes any live lice, making them easier to remove at the same time.
- Section the hair. Use clips to divide the hair into small sections, roughly an inch wide. Comb from the roots all the way to the tips, wiping the comb on a white paper towel or cloth after every pass so you can see what you’re removing.
- Repeat daily. Comb every day as long as you’re finding live lice or eggs within a quarter inch of the scalp. Because eggs hatch in 6 to 9 days, daily combing for at least two weeks catches any newly hatched nymphs before they mature enough to lay their own eggs.
This process takes time, especially with thick or long hair. Expect 30 minutes to over an hour per session. It’s tedious, but it’s the method with the best track record. The UC Integrated Pest Management program calls nit combing “key to successful control, regardless of any insecticide treatment used.”
Over-the-Counter Treatments and Resistance
Most drugstore lice treatments contain pyrethrins or permethrin, which target the nervous system of live lice. These products have limited effect on eggs, which is why their instructions call for a second treatment 7 to 10 days later to kill newly hatched nymphs. The problem is that lice in many areas have developed genetic resistance to these chemicals. Studies have found resistance-linked mutations in a significant percentage of lice populations, meaning the treatments may not even kill the adult lice effectively, let alone the eggs.
If you use an over-the-counter product, follow the instructions completely, including the second application. But don’t rely on it alone. Combine any chemical treatment with daily wet combing. If the infestation persists after two rounds of over-the-counter treatment, a healthcare provider can prescribe stronger options that work through different mechanisms, some of which are more effective against eggs.
Using Heat to Kill Eggs
Lice and their eggs die when exposed to temperatures above 125°F for 10 minutes. This isn’t practical to apply directly to someone’s head at home, but it’s useful for dealing with eggs on clothing, bedding, and hair accessories.
For washable items, run them through a hot wash cycle followed by at least 20 minutes in a dryer on high heat. Non-washable items like stuffed animals or decorative pillows can go straight into the dryer on high for 20 minutes. Combs and brushes should be soaked in water heated to about 150°F for 10 minutes.
Professional heated-air treatments are available at lice clinics, where a device blows controlled hot air along the hair shaft to dehydrate eggs in place. These sessions typically take about an hour and can be effective, though they work best when combined with combing to physically remove the dehydrated eggs afterward.
What About Home Remedies?
Olive oil, coconut oil, petroleum jelly, and mayonnaise are commonly suggested as suffocation treatments. The idea is that coating the hair in a thick, oily substance overnight will smother lice and possibly suffocate eggs. There’s some logic to this for live lice, which breathe through small openings that can be blocked. But lice eggs have very low oxygen needs, and there’s no strong evidence that any of these substances reliably kills unhatched eggs.
That said, coating hair in oil or thick conditioner does make combing much easier. If you want to use one of these products, treat it as a combing aid rather than a standalone treatment. Apply generously, comb thoroughly with a metal nit comb, then wash out. The real work is still the comb.
Cleaning Your Home
Lice eggs need the warmth of the human scalp to survive and hatch. An egg that falls off the head onto a pillow or couch is unlikely to hatch at room temperature, and even if a nymph did emerge, it would die within hours without a blood meal. This means you don’t need to deep-clean your entire house or bag up belongings for weeks.
Focus on items that have had direct contact with the infested person’s head in the past 48 hours. Wash pillowcases, sheets, hats, and scarves in hot water and dry on high heat. Vacuum upholstered furniture and car seats. That’s sufficient. Lice don’t live in carpets, and they don’t jump or fly. Spending hours sanitizing your home is time better spent combing.
The Timeline for Complete Removal
Plan on at least two full weeks of daily combing, even if you’re also using a chemical treatment. Here’s why the timeline matters: eggs hatch in 6 to 9 days, and a newly hatched nymph takes another 9 to 12 days to mature enough to reproduce. If you comb daily for 14 days, you’ll catch every generation before it can lay new eggs, breaking the cycle completely.
After two weeks with no live lice found during combing, you can shift to checking every few days for another week to be safe. You may continue to find empty egg casings glued to hair strands for some time. These are cosmetically annoying but harmless. They’ll eventually grow out with the hair or can be removed during regular combing. Both the American Academy of Pediatrics and the National Association of School Nurses have stated that the presence of nits alone, without live lice, should not keep a child home from school.