Getting rid of head lice takes a combination of the right treatment and thorough follow-up, typically over a two-week window. A single application of medication usually isn’t enough because most products kill live lice but not their eggs, which take 6 to 9 days to hatch. That timing gap is the key to the whole process.
Why the Life Cycle Matters
Understanding a few basic timelines makes the difference between clearing an infestation and chasing one in circles. Lice eggs (called nits) hatch in about a week. The newly hatched lice, called nymphs, take another 7 days to mature into egg-laying adults. Adults can survive on a person’s head for up to 30 days, but they die within two days if they fall off and can’t feed.
This is why most treatments require a second application around day 9. The first round kills live lice. The second catches any nymphs that hatched from surviving eggs before they’re old enough to lay new eggs themselves. Skip that second treatment and you risk restarting the whole cycle.
Over-the-Counter Treatments
The most widely available OTC option is 1% permethrin lotion, sold under the brand name Nix. It kills live lice but not unhatched eggs, and it continues killing newly hatched lice for several days after application. It’s approved for children two months and older. You apply it to freshly shampooed, towel-dried hair, leave it on for 10 minutes, then rinse. The American Academy of Pediatrics recommends rinsing over a sink with warm (not hot) water rather than in the shower, to limit how much skin the product contacts.
Here’s the catch: lice in many areas have developed resistance to permethrin. A Canadian study found resistant genes in 133 out of 137 lice populations tested, which helps explain why OTC treatments fail for some families. If permethrin doesn’t work after two or three properly timed applications, it’s time to try a different approach rather than repeating the same product.
When OTC Products Don’t Work
If store-bought treatments fail, prescription options are available. These use different active ingredients that lice haven’t developed widespread resistance to. Some prescription formulas also kill eggs, meaning a single application can be enough. Your pediatrician or family doctor can determine which option fits based on the child’s age and the severity of the infestation.
One important rule: don’t use more of any lice medication than directed, and don’t treat more than two to three times with the same product if it’s not working. Overuse doesn’t improve results and increases the chance of skin irritation.
The Wet Combing Method
Wet combing is a chemical-free approach with solid clinical evidence behind it. You can use it as a standalone treatment or alongside medication to improve your odds. The key is using a fine-toothed lice comb with teeth spaced less than 0.3 mm apart, which is narrow enough to trap both adult lice and nymphs.
Here’s how it works:
- Wash and condition. Shampoo the hair normally, then apply a generous amount of conditioner. This makes the hair slippery and easier to comb through.
- Detangle first. Use a wide-toothed comb to remove all tangles so the fine lice comb can move freely.
- Comb systematically. Switch to the lice comb. Slot the teeth into the hair at the roots, lightly touching the scalp, and draw the comb all the way to the ends with every stroke. Work through the entire head section by section.
- Check after each stroke. Wipe or rinse the comb after every pass to remove any lice or nymphs caught in the teeth.
- Rinse out the conditioner once you’ve combed through all sections.
Repeat this process every 3 days. You’re done when you’ve had four consecutive combing sessions with no lice found. That schedule ensures you catch any newly hatched nymphs before they mature. It requires patience, especially with long or thick hair, but it works and avoids any concerns about chemical resistance.
Skip the Home Remedies
Mayonnaise, olive oil, coconut oil, and similar suffocation methods are popular suggestions online, but the evidence doesn’t support them. While coating the hair in a thick substance may suffocate some adult lice, it doesn’t kill the eggs. That means the infestation can restart within days. Pediatricians at the University of Utah have described these remedies as both unreliable and potentially messy enough to discourage the thorough follow-up that actually clears an infestation.
Cleaning Your Home
The good news: lice can’t survive long away from a human head. They die within two days without a blood meal, and nits that fall off generally die within a week because they need body heat to hatch. This means you don’t need to fumigate your house or throw away stuffed animals. Focus your cleaning efforts narrowly.
Wash any bedding, clothing, and towels used by the infested person in the two days before treatment. Use the hot water cycle at 130°F or higher and dry on high heat. Soak combs and brushes in hot water (at least 130°F) for 5 to 10 minutes. For items that can’t be washed, like stuffed animals or decorative pillows, sealing them in a plastic bag for two weeks will kill any lice or nits. Vacuum upholstered furniture and car seats, then move on. Spending hours deep-cleaning the house isn’t necessary and takes time away from the treatments that actually matter.
Checking and Treating the Whole Family
Before treating anyone, confirm that live lice are actually present. Nits alone, especially those found more than a quarter inch from the scalp, are often empty casings from a previous infestation and don’t necessarily mean active lice. The best way to check is wet combing with conditioner over a white paper towel, where live lice are easy to spot.
Check everyone in the household, but only treat those who have confirmed live lice. Preventive treatment of unaffected family members isn’t recommended. Sharing beds, brushes, hats, and helmets are the most common transmission routes, so separating those items during active treatment helps prevent spread within the family.
Going Back to School
Both the American Academy of Pediatrics and the National Association of School Nurses recommend against “no-nit” policies, which keep children home until every nit is removed. Their reasoning is straightforward: nits attached to hair shafts are very unlikely to transfer to other people, misdiagnosis of nits by non-medical staff is common, and the days of missed school cause more harm than the lice themselves. A child with lice can finish the school day, get treated that evening, and return to class the next morning. If your school still enforces a no-nit policy, it may help to share this guidance from the AAP with school administrators.