The most reliable way to tell if you have lice is to find a live louse or nit (egg) attached to a hair shaft. Itching is the symptom most people associate with lice, but it can take four to six weeks to develop during a first infestation, so you can have lice for over a month without feeling anything at all. That means a physical check is the only sure method.
Why You Might Not Feel Itchy Yet
The itching from head lice isn’t caused by the bugs biting you. It’s an allergic reaction to their saliva, and your immune system needs time to develop that sensitivity. If you’ve never had lice before, you may go four to six weeks with no itching whatsoever. Even with a light infestation, some people never itch at all. So waiting for your scalp to feel itchy before checking is not a reliable strategy.
If you do feel symptoms, the most common ones are a persistent itch (especially behind the ears and along the back of the neck), a tickling sensation like something is moving in your hair, and small sores or red bumps on the scalp from scratching. On darker skin tones, those bumps can be harder to spot visually. In children, repeated scratching sometimes leads to swollen lymph nodes in the neck, which feel like small, tender lumps.
What Lice and Nits Look Like
Adult lice are dark in color and roughly the size of a poppy seed. They move quickly and avoid light, which makes them surprisingly hard to spot just by looking. Nymphs (baby lice) are even smaller and nearly translucent.
Nits are easier to find because they don’t move. They’re tiny oval-shaped eggs, white or yellowish-brown, glued to individual hair shafts about a quarter inch from the scalp. That proximity to the scalp matters: lice lay their eggs close to the skin because the warmth helps them develop. The two places to focus your search are behind the ears and along the hairline at the back of the neck. These warm, sheltered spots are where lice prefer to lay eggs.
Nits vs. Dandruff
A lot of people mistake dandruff flakes, dried hair product, or hair casts for nits. There’s a simple physical test: try to flick or slide the speck off the hair strand. Dandruff comes off easily. Nits do not. They’re cemented to the shaft at an angle and resist being pulled free. You’ll need to pinch them between your fingernails and drag them along the strand to remove one.
Hair casts, which are tiny tubes of skin that form around the hair shaft, can also look like nits. The difference is that hair casts slide freely up and down the entire length of the hair with very little effort, while a true nit stays firmly in place. Hair casts also don’t cause itching or spread between people.
The Wet Combing Method
Simply parting the hair and looking at the scalp is the way most people check for lice, but it misses a lot. Research comparing visual inspection to wet combing found that about 30% of “positive” visual diagnoses were wrong, and 10% of “negative” ones missed an actual infestation. In other words, just eyeballing the scalp gives you a roughly one-in-three chance of a false alarm and a one-in-ten chance of missing lice entirely.
Wet combing is significantly more accurate. Here’s how to do it:
- Wet the hair thoroughly. Lice slow down and stop moving as quickly when hair is wet, making them easier to trap.
- Apply a generous amount of conditioner. This makes the comb glide smoothly and helps lice and nits show up more clearly against the white residue.
- Use a fine-toothed lice comb. Regular combs have teeth that are too far apart. Metal lice combs with closely spaced teeth work best.
- Comb systematically from the scalp outward. Start at one side of the head and work in small sections all the way to the other side. After each stroke, wipe the comb on a white paper towel or tissue and look for lice or nits.
- Use a magnifying glass if you have one. A 10x magnifier helps you identify nymphs, which are tiny enough to miss with the naked eye.
The whole process takes about 10 to 15 minutes for most hair lengths. If you find even one live louse or a nit firmly attached close to the scalp, that confirms an active infestation.
What a Live Louse Looks Like on the Comb
When you wipe the comb onto a white surface, a live louse will appear as a small dark speck, roughly the size of a sesame seed or smaller. Give it a moment. If it’s alive, you’ll see it move. Nits wiped onto the towel look like tiny dots, white to tan in color. If you’re only finding nits that are far from the scalp (more than half an inch away), those may be old, already-hatched shells from a previous infestation rather than evidence of active lice.
Signs That Scratching Has Caused a Problem
Most lice infestations are annoying but not dangerous. The main complication comes from scratching. Persistent scratching can break the skin on your scalp, neck, and behind your ears, creating small open sores. These sores can become infected with bacteria, leading to crusting, oozing, or increased redness and tenderness around the area. If you notice sores that seem to be getting worse rather than healing, or if the lymph nodes along the sides of the neck become swollen and tender, the scratching has likely opened the door to a secondary infection that needs treatment.
Who Gets Lice
Lice spread through direct head-to-head contact. They can’t jump or fly. An estimated 6 to 12 million children between the ages of 3 and 11 are affected each year in the United States alone. Adults who live with or care for school-age children are the most likely grown-ups to get lice, but anyone with hair can. Having lice has nothing to do with hygiene. Lice actually prefer clean hair because it’s easier to grip.
If one person in your household has confirmed lice, check everyone else using the wet combing method. People sharing the same bed or who have had head-to-head contact in the past two weeks are most at risk.