How to tell if a person has lice? - briefly
Examine the scalp and hair for live insects or their eggs, which look like tiny, translucent ovals attached firmly near the scalp, especially at the nape and behind the ears. Persistent itching that intensifies over several days strongly suggests an infestation.
How to tell if a person has lice? - in detail
A lice infestation manifests through several observable signs that can be identified by careful examination of the scalp, hair, and surrounding environment.
The most reliable indicator is the presence of live insects or their eggs. Adult lice are approximately 2–3 mm long, grayish‑brown, and move quickly when the hair is disturbed. Nits—lice eggs—appear as tiny, oval, white or yellowish shells firmly attached to the hair shaft, usually within ¼ inch of the scalp. Because nits harden after hatching, they become translucent and may be mistaken for dandruff; however, unlike dandruff, they cannot be easily brushed away.
Additional symptoms include:
- Persistent itching, especially after a few days, caused by an allergic reaction to lice saliva.
- Redness or small sores on the scalp from scratching.
- A feeling of movement or crawling on the head, often reported by children.
To confirm an infestation, follow a systematic inspection:
- Separate a small section of hair close to the scalp, using a fine‑toothed comb or a lice detection comb.
- Pull the hair taut and run the comb from the root to the tip, wiping the comb on a white surface after each pass.
- Examine the comb for live lice or nits. A single live specimen confirms an infestation; several nits within ¼ inch of the scalp strongly suggest active infestation.
- Repeat the process on multiple sections of the head, covering the entire scalp, because lice tend to cluster in the nape, behind the ears, and along the hairline.
When inspecting others, use disposable gloves and a clean comb for each individual to prevent cross‑contamination. In environments such as schools or daycare centers, conduct visual checks of hair and clothing, and consider using a handheld magnifier (10×) to improve detection of tiny nits.
If live lice or viable nits are found, initiate treatment promptly and re‑inspect after 7–10 days to ensure eradication, as newly hatched lice may emerge from surviving eggs. Regular follow‑up examinations for at least three weeks help prevent recurrence.