The most reliable sign of a lice infestation is finding a live louse or nit (egg) attached to a hair shaft. Itching is the symptom most people associate with lice, but it can take weeks to develop after the initial exposure, so you can have lice and not feel itchy at all. Knowing exactly what to look for, and where, makes the difference between catching an infestation early and missing it entirely.
Early Symptoms to Watch For
Itching is the hallmark symptom, but it’s not actually caused by the lice crawling around. It’s an allergic reaction to their saliva, which they deposit when they bite. Because your body needs time to develop that allergic response, itching often doesn’t start until two to six weeks after lice first arrive. If you’ve never had lice before, the delay can be even longer.
Other signs that may show up before or alongside itching include a tickling or crawling sensation on the scalp, small red bumps on the scalp or nape of the neck, and difficulty sleeping (lice are most active in the dark). You might also notice tiny dark specks on your pillowcase or collar, which are lice droppings.
What Lice and Nits Look Like
Adult lice are about the size of a sesame seed, roughly 2 to 3 millimeters long. They’re tan to grayish-white and have six legs. They don’t fly or jump. Instead, they crawl quickly through hair, which is why spotting a live louse with the naked eye can be surprisingly difficult. They actively avoid light, so parting the hair to look often sends them scurrying.
Nits are easier to find because they don’t move. They’re oval-shaped, about the size of a pinhead, and white or yellowish-brown. You’ll typically find them glued to individual hair strands about a quarter inch from the scalp, where the warmth helps them incubate. The areas behind the ears and along the nape of the neck are the most common spots.
Nits vs. Dandruff
This is one of the most common sources of confusion. Both look like small white specks in the hair, but they behave very differently. Dandruff flakes off easily when you flick it or run your fingers through your hair. Nits are cemented to the hair shaft and won’t budge without real effort. If you can easily brush a white speck away, it’s almost certainly not a nit. If it’s firmly stuck and you need to slide it along the strand with your fingernails to remove it, that’s a strong indicator of lice.
The Best Way to Check: Wet Combing
Simply looking through dry hair is unreliable. A study comparing the two methods found that wet combing correctly identified active infestations 90.5% of the time, while visual inspection caught only 28.6%. That means a quick look through dry hair misses roughly seven out of ten active cases.
Wet combing works better because conditioner slows lice down and makes hair easier to section through systematically. Here’s how to do it:
- Wash and condition. Use regular shampoo, then apply a generous amount of conditioner. Don’t rinse the conditioner out yet.
- Detangle first. Use a wide-toothed comb to remove tangles so the fine-toothed comb can glide through without dragging.
- Switch to a lice comb. Use a fine-toothed comb with teeth spaced less than 0.3 millimeters apart. Place the teeth at the roots, lightly touching the scalp, and draw the comb slowly from root to tip.
- Check after every stroke. Wipe the comb on a white paper towel or tissue after each pass. Live lice and nits will be visible against the white background.
- Work section by section. Don’t skip areas. Focus especially behind the ears and at the nape of the neck.
- Rinse and repeat. After combing through all sections, rinse out the conditioner and comb through once more to catch anything you missed.
The whole process takes about 10 minutes for short hair and up to 30 minutes for longer hair. It’s worth the time. If you find even one live louse or nit firmly attached near the scalp, you have an active infestation.
Where on the Scalp to Focus
Lice prefer warm, sheltered spots. The two areas where they concentrate most heavily are behind the ears and along the back of the neck near the hairline. These are the spots where nits are most often found, and where bites tend to cluster. If you’re short on time or checking a restless child, examine these two zones first. Finding nothing in either area doesn’t completely rule lice out, but it does lower the probability significantly.
Conditions That Mimic Lice
Not every itchy scalp means lice, and not every white flake is a nit. Several common conditions can produce similar symptoms.
Dandruff causes flaking and itching but produces loose, dry flakes that brush off easily. Scalp psoriasis creates thick, crusty patches of built-up skin that can itch intensely but look distinctly different from individual nits. Both conditions lack the key finding of live insects or firmly attached eggs on the hair shaft.
Less commonly, other tiny insects like fleas or bedbugs can end up on your scalp and cause bites, though they don’t live there the way lice do. And some people experience a crawling sensation on the scalp with no bugs present at all. This can be triggered by medication side effects, stress, or other health conditions. If you’ve done a thorough wet combing and found nothing, the sensation is likely caused by something other than lice.
What Confirms an Active Infestation
Finding nits alone can be ambiguous. Nits found more than a quarter inch from the scalp are often empty shells from a previous infestation or eggs that never hatched. They can linger in the hair for months after lice are gone. The strongest confirmation of an active case is finding a live, moving louse. The next strongest is finding nits very close to the scalp, within that quarter-inch zone, which indicates eggs that were recently laid and are likely viable.
If your wet combing turns up only a few nits far from the scalp and no live lice, you may be looking at remnants of an old infestation rather than a current one. Repeat the wet combing a few days later to be sure. If lice are present, you’ll eventually catch one in the comb.