How can you tell that lice have infested the head? - briefly
Live lice or their attached eggs (nits) on hair shafts close to the scalp indicate an infestation, and persistent itching accompanied by red bite marks confirms the problem.
How can you tell that lice have infested the head? - in detail
A head‑lice infestation can be confirmed by observing several distinct signs.
- Intense pruritus – persistent itching, especially behind the ears and at the nape, often intensifies after warm showers.
- Live insects – adult lice are about 2–4 mm long, gray‑brown, and move quickly when the scalp is disturbed. They cling to hair shafts close to the skin.
- Nits attached to hair – oval, white or yellowish eggs are firmly glued to the shaft within 1 cm of the scalp. They do not slide easily when the hair is brushed.
- Brown or black specks – expelled nits or fecal debris appear as tiny, dark particles on clothing, pillows, or the scalp.
- Scalp irritation – redness, soreness, or secondary infections may develop from constant scratching.
Systematic inspection
- Separate a small section of hair near the crown, behind each ear, and at the hairline.
- Use a fine‑tooth lice comb on wet hair, moving the comb slowly from scalp to tip.
- After each pass, wipe the comb on a white surface or magnifying glass to detect lice or nits.
- Repeat the process on multiple sections; a single live louse confirms infestation.
Differentiating from dandruff
- Dandruff flakes are loose, white, and easily removed; nits remain attached to the hair shaft.
- Dandruff does not cause the characteristic crawling sensation or rapid movement when hair is disturbed.
When professional evaluation is warranted
- Presence of live lice or a substantial number of nits (more than a few).
- Persistent itching despite over‑the‑counter treatments.
- Signs of secondary infection such as swelling, pus, or severe redness.
By applying thorough visual checks and recognizing the specific symptoms listed above, one can reliably determine whether the scalp is infested with lice.