Why can't I get rid of lice? - briefly
The infestation often persists because treatment does not eliminate nits and because lice may develop resistance to common pediculicides. Reinvasion from untreated contacts or incorrect application of products also sustains the problem.
Why can't I get rid of lice? - in detail
Persistent head‑lice infestations result from several biological and environmental factors.
Adult lice survive for about 30 days on the scalp, laying up to 10 eggs per day. Eggs (nits) adhere firmly to hair shafts and hatch only after 7–10 days, creating a continuous cycle that resists short‑term treatments.
Common obstacles include:
- Incomplete removal of nits; even a few surviving eggs repopulate the scalp.
- Resistance to common pediculicides; repeated use of permethrin or pyrethrin selects for resistant lice strains.
- Re‑infestation from close contact with untreated individuals, shared objects (combs, hats, bedding) or contaminated environments.
- Incorrect application of topical agents; insufficient contact time or failure to follow manufacturer instructions reduces efficacy.
- Underlying scalp conditions (seborrhea, dermatitis) that provide a favorable habitat for lice survival.
Effective eradication requires a multi‑step approach:
- Apply a proven ovicidal product according to label directions, ensuring the recommended exposure period.
- Conduct a thorough nit combing with a fine‑toothed lice comb after each treatment, repeating every 2–3 days for at least two weeks.
- Wash all personal items (bedding, towels, clothing) in hot water (≥ 60 °C) or seal them in a plastic bag for two weeks to kill undiscovered lice.
- Treat all close contacts simultaneously, even if asymptomatic, to prevent cross‑contamination.
- If resistance is suspected, switch to an alternative class of pediculicide (e.g., ivermectin, spinosad) or consult a healthcare professional for prescription options.
Monitoring continues for 4 weeks after the final treatment. Absence of live lice and nits during this period confirms successful elimination. Regular checks and prompt retreatment at the first sign of recurrence prevent re‑establishment of the infestation.