The most reliable way to check for lice is wet combing, which catches about 91% of active infestations compared to just 29% for a dry visual inspection. All you need is a metal fine-toothed comb, some conditioner, and good lighting. A thorough check takes at least 10 minutes, sometimes longer for thick or curly hair.
Why Wet Combing Works Best
Head lice move quickly on dry hair, which is why simply parting the hair and looking often misses them. A visual inspection catches fewer than 1 in 3 active infestations. Wet combing slows lice down (conditioner essentially immobilizes them) and forces them onto the comb where you can actually see them. It’s the same method school nurses and pediatricians rely on.
One exception: visual inspection is better at spotting signs of an old, already-resolved infestation, picking up leftover nits about 86% of the time. But if your goal is to find out whether someone has lice right now, wet combing is far more accurate.
What You Need
- A metal nit comb. The teeth need to be long and very close together. Metal combs are rigid enough to pull nits off the hair shaft, while plastic combs tend to flex and let them slip through. If you don’t have a lice comb, a metal flea comb from a pet store works the same way.
- White conditioner or a light-colored towel. White conditioner makes lice easier to spot when you wipe the comb. A white paper towel or cloth also works for examining what comes off.
- Bright light. A desk lamp angled at the scalp, or natural sunlight near a window, makes a significant difference.
- Hair clips. Sectioning the hair keeps you organized so you don’t skip areas.
Step-by-Step Wet Combing
Start by wetting the hair thoroughly and applying a generous amount of conditioner. This detangles the hair so the comb moves smoothly and traps lice in the conditioner rather than letting them scatter.
Use hair clips to divide the hair into small sections, roughly one to two inches wide. Starting at the scalp, place the comb flat against the skin and draw it all the way from the root to the tip of the hair. After each stroke, wipe the comb on a white paper towel or tissue and look for anything that came off. Lice are tan or grayish-brown, about the size of a sesame seed. Nymphs (baby lice) are smaller and nearly translucent.
Work section by section across the entire head. Pay extra attention to four areas where lice concentrate most: the crown of the head, the bangs, behind both ears, and the nape of the neck. These spots are warmer, which lice prefer for laying eggs. Plan on at least 10 minutes for the full process, and longer for thick, long, or curly hair.
How to Tell Nits From Dandruff
Nits are the eggs lice glue to individual hair strands, and they’re easy to confuse with dandruff or hair product residue. The simplest test: try to slide it off. Dandruff flakes right off with your fingers. Nits are cemented to the hair shaft and won’t budge without pinching them between your fingernails and pulling them down the strand.
Shape helps too. Nits are tiny, teardrop-shaped, and usually white or yellow. Empty casings from already-hatched eggs look more translucent or gray. Dandruff, by contrast, is irregularly shaped and tends to be flat and flaky. Nits also cluster in predictable spots, particularly around the ears and along the neckline, while dandruff is scattered more randomly across the scalp.
Active Infestation vs. Old Nits
Finding nits alone doesn’t necessarily mean you’re dealing with a current infestation. The distance between the nit and the scalp tells you a lot. Viable eggs sit within about a quarter inch (6 mm) of the scalp, where body heat keeps them warm enough to develop. Nits found further than a quarter inch from the scalp are almost always dead or already hatched, since hair growth has carried them away from the warmth they need.
The CDC considers finding a live nymph or adult louse the definitive sign of an active infestation. If the only nits you find are more than a quarter inch from the scalp and you see no live bugs, the infestation is likely old and already over. This distinction matters because it can save you from unnecessary treatment. If you do find nits close to the scalp but no live lice, it’s worth rechecking with a wet comb in a few days to confirm.
What Live Lice Look Like
Adult lice are about the size of a sesame seed, flat, wingless, and range from tan to grayish-white. They have six legs with small claws designed to grip hair strands, and they move fast on dry hair, which is another reason they’re easier to catch in conditioner. Nymphs look similar but smaller, closer to the size of a pinhead. Both avoid light and will try to crawl away when you part the hair, so check quickly once you expose a section of scalp.
You might also notice tiny dark specks on the scalp or pillowcase. These are louse droppings, and while they’re not diagnostic on their own, they’re another clue that warrants a closer wet comb check.
Checking Multiple Family Members
If one person in the household has lice, check everyone. Lice spread through direct head-to-head contact, so siblings, partners, and anyone who shares a bed are the highest priority. Use a separate comb for each person, or clean the comb between checks by soaking it in hot water (at least 130°F) for 5 to 10 minutes.
Recheck anyone who was negative after 7 to 10 days. Nits take about a week to hatch, so an early check can miss an infestation that was just getting started. Two negative wet comb checks spaced a week apart gives you strong confidence that someone is clear.