How to know that there are no lice? - briefly
Inspect the scalp and hair in bright light, looking for live insects, firmly attached eggs, or persistent itching; if none are found, the head is free of infestation. Use a fine-toothed comb to verify that no nits remain hidden.
How to know that there are no lice? - in detail
To confirm that a person or a living environment is free of head‑lice, follow a systematic examination that combines visual observation, tactile assessment, and appropriate tools.
First, separate the hair from the scalp using a fine‑toothed lice comb. Work in sections, starting at the crown and moving toward the hairline. After each pass, wipe the comb on a white tissue or rinse it under running water. Any live insects, nymphs, or viable eggs will be clearly visible against the background.
Second, conduct a close visual inspection of the scalp and hair shafts. Use a bright light or a magnifying lens to look for:
- Live insects, typically 2–4 mm in length, with a grayish‑brown or tan color.
- Nits attached firmly to the hair shaft within ¼ inch of the scalp; they appear as tiny, oval, yellow‑white bodies.
- Red or irritated patches that may indicate recent bites.
Third, perform a tactile check. Run fingertips through the hair, feeling for movement or the distinctive “candle‑wick” texture of nits stuck to the shaft. Absence of any crawling sensation or gritty feeling supports the conclusion of no infestation.
Fourth, examine personal items that could harbor lice: hats, scarves, pillowcases, and hairbrushes. Wash these in hot water (≥ 130 °F/54 °C) or place them in a sealed bag for two weeks to ensure any hidden stages are eliminated.
Fifth, repeat the combing and visual inspection after 7–10 days. This interval matches the life cycle of lice and ensures that any newly hatched nymphs, which may have been missed initially, are detected.
If all examinations over two consecutive weeks reveal no live insects, viable eggs, or signs of irritation, the area can be considered free of head‑lice. Persistent uncertainty or recurring findings warrant a professional assessment by a healthcare provider.