How should vinegar be diluted to kill lice? - briefly
Mix one part white vinegar with three parts water and apply to the scalp for 10‑15 minutes before rinsing. Repeat the treatment every other day for two weeks to ensure eradication.
How should vinegar be diluted to kill lice? - in detail
Vinegar contains acetic acid, which can disrupt the exoskeleton of head‑lice and impair their ability to cling to hair shafts. Effective concentrations are lower than the undiluted 5 % solution sold for culinary use, because full strength may cause scalp irritation while still achieving lethality.
A practical dilution for lice control balances efficacy and tolerability. Mixing one part white distilled vinegar with two parts water yields an approximate 1.7 % acetic‑acid solution; this concentration has been shown to immobilise nymphs and adult lice within minutes. For individuals with sensitive skin, a milder ratio of one part vinegar to three parts water (≈1.3 % acetic acid) may be employed, extending exposure time to 15–20 minutes. Undiluted vinegar is discouraged because of the risk of burns and dermatitis.
Application protocol
- Prepare the solution in a clean container, ensuring accurate measurement of vinegar and water.
- Perform a 24‑hour patch test on a small scalp area; discontinue if redness or itching develops.
- Apply the mixture generously to dry hair, focusing on the scalp and the length of each strand.
- Cover the hair with a shower cap to prevent evaporation; maintain contact for 10–15 minutes.
- Rinse thoroughly with lukewarm water; follow with a regular shampoo if desired.
- Repeat the treatment after 7 days to target newly hatched lice that survived the first exposure.
Safety considerations
- Use only white distilled vinegar; apple‑cider varieties contain additional compounds that may affect scalp pH.
- Avoid contact with eyes, open wounds, or mucous membranes; flush immediately with water if exposure occurs.
- Do not combine vinegar with other chemical lice treatments, as synergistic irritation may result.
- Store any leftover solution in a clearly labelled container, away from children.
When applied correctly, a diluted acetic‑acid preparation offers a low‑cost, non‑chemical option for reducing head‑lice infestations while minimising adverse skin reactions.