The most reliable way to check for head lice is to comb through wet, conditioned hair with a fine-toothed metal nit comb, working section by section under good lighting. A visual scan of dry hair can spot a heavy infestation, but wet combing catches cases that a quick look will miss. Here’s exactly what to look for, where to look, and how to tell lice apart from harmless flakes.
What You’re Looking For
An active head lice infestation has three possible signs: live lice, nymphs (young lice), and nits (eggs glued to hair shafts). Live adult lice are about the size of a sesame seed, tan to grayish-white, and move quickly away from light. That speed is exactly why they’re hard to spot on dry hair. Nymphs are smaller and nearly translucent, making them even harder to see.
Nits are oval-shaped, roughly the size of a pinhead, and attached firmly to individual hair strands close to the scalp. Fresh, viable nits look yellowish-brown or tan. After hatching, the empty shells turn white or clear, which is when people most often confuse them with dandruff. A female louse lays each egg near the base of a hair shaft, and it takes about 6 to 9 days to hatch.
Location matters. Nits found within a quarter inch of the scalp are the ones most likely to be alive and ready to hatch. Nits farther out on the hair shaft are generally old casings or already hatched, and on their own don’t confirm an active infestation.
Where to Focus Your Search
Lice prefer warm, sheltered areas of the scalp. The three hotspots are behind the ears, along the neckline at the back of the head, and under bangs near the forehead. Start your check in these areas. If you’re going to find evidence of lice, it will almost always show up in one of these zones first.
In a light infestation, there may be fewer than 10 live lice on the entire head, so checking only the top or crown and calling it clear isn’t enough. You need to look at the warm edges of the scalp where lice feed and lay eggs.
The Wet Combing Method
Wet combing is the gold standard for detection. It slows lice down (they can’t scurry as fast on wet hair), makes nits easier to see against damp strands, and lets the comb glide without pulling. Here’s how to do it:
- Gather your tools. You need a metal nit comb with long, closely spaced teeth. Metal combs are significantly more effective than plastic ones because the teeth are rigid and narrow enough to trap both nits and small nymphs. You also need regular hair conditioner, a spray bottle of water, good lighting (natural daylight or a bright lamp), and white paper towels or a light-colored cloth.
- Wet and condition the hair. Apply a generous amount of conditioner to damp hair. This lubricates the strands so the comb slides through without snagging, and it temporarily immobilizes live lice.
- Divide the hair into sections. Use clips to pin up most of the hair. Work with one small section at a time, roughly an inch wide.
- Comb from root to tip. Place the comb’s teeth flat against the scalp and draw it slowly all the way through to the ends. After each stroke, wipe the comb on the white paper towel and look carefully at what came out. Live lice will appear as tiny dark or tan specks that may still be moving. Nits will look like small, teardrop-shaped dots stuck to the hair strand.
- Repeat through every section. Work methodically around the entire head. Pay extra attention behind the ears and along the nape of the neck. A thorough check on shoulder-length hair takes about 15 to 20 minutes.
Checking Dry Hair
If you don’t have a nit comb handy and just want a quick first look, you can do a visual check on dry hair. Seat the person under a strong light, part the hair in several places, and look closely at the scalp and the first quarter inch of the hair shafts. Lift and separate sections with your fingers or the end of a regular comb, focusing on behind the ears and the back of the neck.
This method works better for spotting nits than live lice, since adult lice will dart away as soon as you part the hair. If you see suspicious white or tan specks, the quick test is to try to flick or slide the speck off the strand. Dandruff and dry skin flakes come off easily. Nits do not. They’re cemented to the hair and will resist your fingers. You’ll need to pinch them and slide them firmly along the strand to remove them.
Nits vs. Dandruff vs. Other Look-Alikes
The most common false alarm is dandruff. Both nits and dandruff are small, pale, and found near the scalp, but they behave differently. Dandruff flakes are irregularly shaped, sit loosely on hair or the scalp surface, and brush away with minimal effort. Nits are uniform, oval, and glued at an angle to one side of a single hair strand. They won’t budge when you shake or blow on the hair.
Other things that mimic nits include hair spray residue, sand, and DEC plugs (tiny white cylinders of dried scalp oil that slide along the hair). The slide test works for all of these: if it moves freely up and down the strand, it’s not a nit. If it’s firmly anchored and requires real pressure to move, treat it as a nit until proven otherwise.
How to Confirm an Active Infestation
Finding nits alone doesn’t automatically mean the infestation is active. Nits more than a quarter inch from the scalp have likely already hatched or died, especially in warmer climates where hair grows quickly. What confirms a current, active case is finding either a live crawling louse or nits within a quarter inch of the scalp.
If you find only a few distant nits and no live lice after a thorough wet combing, the infestation may already be over. But because nits can be easy to miss, the CDC recommends rechecking every 2 to 3 days for at least two weeks. This catches any nymphs that may have hatched since your last check, since eggs take about a week to hatch and young lice need another 9 to 12 days to mature and start laying their own eggs.
Checking the Whole Household
If you find crawling lice or close-to-scalp nits on one person, check everyone in the household using the same wet combing method. Lice spread through direct head-to-head contact, so siblings, partners, and anyone who shares a bed or pillow with the affected person should be examined. Only treat people who actually have live lice or viable nits. Preventive treatment on people without evidence of lice isn’t necessary and won’t prevent future spread.
Keep in mind that itching is an unreliable signal. Some people with lice never itch at all, while others don’t develop itching until weeks after the infestation begins. The only way to know for sure is to look.