How should 70 % vinegar be diluted for lice treatment? - briefly
Mix one part 70 % vinegar with an equal part water to achieve roughly a 35 % solution, then further dilute to about 5 % by adding twelve parts water (1 : 13 total). Use the resulting low‑strength solution for lice treatment.
How should 70 % vinegar be diluted for lice treatment? - in detail
A 70 % acetic acid solution contains 700 mL of pure vinegar per litre. For safe topical use against head‑lice, the concentration should be reduced to approximately 5 %–10 % acetic acid. The following procedure achieves the desired strength.
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Measure the required volume of the 70 % solution.
Example: to prepare 200 mL of a 7 % mixture, start with 20 mL of the concentrated vinegar (20 mL × 0.70 = 14 mL pure acid, which equals 7 % of the final 200 mL). -
Add distilled or boiled‑then‑cooled water to reach the target volume.
Continuing the example, add 180 mL of water to the 20 mL of concentrate, mixing thoroughly. -
Verify the final volume with a calibrated container; adjust with small amounts of water if necessary.
Safety considerations
- Perform the dilution in a well‑ventilated area; the vapour from concentrated acetic acid is irritating.
- Wear gloves and eye protection during handling.
- Store the diluted solution in a tightly sealed, child‑proof container, labelled with concentration and date of preparation. Use within 48 hours to avoid microbial growth.
- Conduct a patch test on a small skin area before full application; discontinue if redness or burning occurs.
Application guidelines
- Apply the solution to dry hair, ensuring thorough saturation of the scalp and hair shafts.
- Leave the mixture on for 10–15 minutes, then rinse with lukewarm water.
- Follow with a gentle combing session using a fine‑toothed lice comb to remove dead nits.
- Repeat the treatment after 7 days to eliminate any newly hatched lice.
Alternative dilution ratios
- For a 5 % solution: use 7.1 mL of 70 % vinegar diluted to 100 mL with water.
- For a 10 % solution: use 14.3 mL of 70 % vinegar diluted to 100 mL with water.
These calculations maintain a precise acetic‑acid content, ensuring efficacy while minimizing the risk of skin irritation.