How long do head lice survive on items? - briefly
Head lice can remain viable on dry objects such as combs, hats or bedding for up to 48 hours, after which they usually die. On moist surfaces they may survive slightly longer, but survival rarely exceeds two days.
How long do head lice survive on items? - in detail
Head lice (Pediculus humanus capitis) can remain alive on non‑living surfaces for a limited period because they depend on blood meals from a human host. On dry items such as combs, hats, pillowcases, or clothing, adult lice typically survive for 24–48 hours at room temperature (20‑25 °C) and normal humidity (40‑60 %). Under cooler, drier conditions, survival may drop to 12–24 hours; in warm, humid environments, it can extend up to 48 hours. Nymphs, being smaller and less robust, usually die within 12–24 hours under the same conditions.
Key factors influencing survival time:
- Temperature: Higher temperatures (above 30 °C) accelerate desiccation, reducing viability; lower temperatures (below 10 °C) also shorten lifespan but may delay death slightly.
- Relative humidity: Moisture above 70 % prolongs survival; dry air below 30 % causes rapid dehydration.
- Material type: Porous fabrics (e.g., cotton) retain moisture longer than synthetic fibers, allowing lice to survive marginally longer.
- Exposure to sunlight: Direct UV light damages lice quickly, often killing them within a few hours.
Practical implications for decontamination:
- Wash washable items in hot water (≥ 60 °C) for at least 10 minutes, then dry on high heat.
- Seal non‑washable objects in a sealed plastic bag for 48 hours; the lice will die without a host.
- Use a clothes dryer on high heat for 30 minutes for clothing and bedding.
- Discard or treat hair accessories that cannot be cleaned, as they may harbor viable lice for up to two days.
Overall, head lice do not persist beyond two days on most inanimate objects when environmental conditions are typical for indoor settings.