How long can lice survive off a head on bedding? - briefly
Head lice typically survive no more than 24–48 hours on bedding or other surfaces without a host; humidity and temperature can extend survival slightly, but they rarely live beyond two days.
How long can lice survive off a head on bedding? - in detail
Head lice (Pediculus humanus capitis) can remain alive on fabrics such as sheets, pillowcases, or blankets only for a limited period when they are separated from a human scalp. Their survival depends primarily on ambient temperature, relative humidity, and the availability of a suitable environment that prevents desiccation.
- At typical indoor temperatures (20 °C–25 °C) and moderate humidity (40 %–60 %), adult lice generally survive for 24–48 hours. Within this window, they retain mobility and can re‑infest a host if contact occurs.
- In cooler, moist conditions (15 °C–20 °C with humidity above 70 %), survival may extend to 72 hours or, in rare cases, up to five days. The higher moisture slows water loss from the insect’s exoskeleton.
- In hot, dry environments (above 30 °C with humidity below 30 %), desiccation occurs rapidly; most lice die within 12 hours.
Nymphs and eggs (nits) are less tolerant of off‑host conditions. Nymphs, lacking the protective cuticle of adults, typically die within 12–24 hours under average indoor conditions. Nits, while more resistant to temperature fluctuations, cannot hatch without a blood meal; they remain viable for several days but will not develop unless they are transferred back to a scalp.
Because lice require human blood for nourishment, they do not reproduce or increase their numbers on bedding. Consequently, the risk of re‑infestation from contaminated linens decreases sharply after the first 48 hours under normal household conditions.
Practical measures to eliminate any remaining insects from bedding include:
- Washing sheets, pillowcases, and blankets in hot water (≥ 60 °C) for at least ten minutes.
- Drying the laundered items on high heat for a minimum of 30 minutes.
- Vacuuming mattresses and bedroom furniture, then discarding or sealing the vacuum bag.
- Storing unused bedding in sealed plastic bags for a week to ensure any surviving lice die from starvation and desiccation.
In summary, head lice can survive on bedding for up to two days under typical indoor conditions, with possible extension to several days only in cool, humid environments. Prompt laundering and thorough cleaning effectively eradicate the insects and prevent re‑infestation.