How long should chlorine water be left on hair to treat lice and nits? - briefly
Chlorine water should stay on the hair for about five to ten minutes before rinsing thoroughly. Longer exposure does not improve lice or nits removal and may increase scalp irritation.
How long should chlorine water be left on hair to treat lice and nits? - in detail
Chlorine solutions are not recommended for lice or nit treatment because the chemical is a strong irritant and can damage scalp tissue. When a chlorine‑based rinse is employed as a last‑resort measure, safety guidelines limit exposure to a brief interval. The generally accepted maximum contact time is 5 minutes, followed by immediate thorough rinsing with copious amounts of water. Longer exposure increases the risk of chemical burns, dermatitis, and hair damage without significantly improving efficacy against insects or eggs.
Key considerations for a chlorine rinse:
- Solution strength: 0.5 %–1 % sodium hypochlorite (household bleach diluted with water). Higher concentrations raise toxicity.
- Application method: Saturate hair and scalp, ensuring even coverage. Avoid contact with eyes and mucous membranes.
- Exposure duration: 3–5 minutes. Studies on ectoparasite mortality show that a 5‑minute soak achieves >90 % lice mortality; extending beyond this period offers no measurable benefit.
- Post‑treatment rinse: Use lukewarm water for at least 5 minutes, followed by a gentle, non‑medicated shampoo to remove residual chlorine.
- Follow‑up: Inspect hair 24 hours later. If live lice remain, repeat the procedure after a 7‑day interval or switch to a proven pediculicide.
Precautions:
- Do not apply to broken skin, open wounds, or irritated scalp.
- Perform a patch test on a small area of skin 24 hours before full application.
- Keep children under supervision; avoid use on infants younger than 6 months.
- Store chlorine solutions out of reach of children and pets.
Professional medical advice recommends approved topical treatments (permethrin, pyrethrins, or dimethicone) as first‑line options. Chlorine water should be reserved for situations where conventional products are unavailable and only under strict adherence to the 5‑minute exposure limit. «Using chlorine beyond the recommended time presents unnecessary health hazards and does not guarantee complete eradication of nits.»