How long do lice live in a bed? - briefly
Lice survive off a host for only about one to two days, after which they die from dehydration and lack of blood meals. In a mattress or bedding, the insects may remain viable for roughly 24 hours, while their eggs require warmth and a host to hatch.
How long do lice live in a bed? - in detail
Lice are obligate ectoparasites that require blood meals to survive. On a human host an adult head‑louse can live up to thirty days, completing several reproductive cycles. Once removed from a host, the insect loses access to nourishment and its lifespan shortens dramatically.
On fabrics such as mattresses, sheets, or pillowcases, survival depends on temperature, humidity, and the presence of a recent blood meal. At room temperature (20‑25 °C) and relative humidity above 50 %, an unfed louse can endure for approximately twenty‑four to forty‑eight hours. Cooler, drier conditions accelerate mortality, reducing the window to less than twelve hours. If a louse has recently fed before contact with bedding, it may retain enough stored blood to survive up to seventy‑two hours, but prolonged survival beyond three days is rare.
Empirical observations indicate the following approximate timeline for off‑host viability:
- 0‑12 h: active, capable of movement and seeking a host.
- 12‑24 h: reduced activity, metabolic slowdown.
- 24‑48 h: near‑death stage, limited response to stimuli.
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48 h: mortality in most cases; occasional individuals may persist up to seventy‑two hours under optimal humidity.
Cleaning measures that eliminate lice from bedding include washing fabrics at a minimum temperature of sixty degrees Celsius, drying on high heat for at least thirty minutes, or sealing items in airtight bags for a week to ensure death of any remaining insects. Vacuuming mattresses and surrounding surfaces removes detached nymphs and eggs, reducing the risk of re‑infestation.
In summary, without a blood source, lice on a mattress or similar surface survive no longer than two days under typical household conditions, with a maximum of three days only under unusually favorable humidity and temperature. Effective sanitation practices eradicate the insects well within this timeframe.