How long should a lice shampoo be left on? - briefly
Leave the product on the hair and scalp for approximately ten minutes, then rinse thoroughly. Follow any additional instructions on the label for optimal results.
How long should a lice shampoo be left on? - in detail
Lice‑treatment shampoos are formulated to work only when the product remains in contact with the scalp and hair for a specific period. Manufacturer instructions typically specify a minimum exposure time that ensures the insecticide penetrates the exoskeleton of the parasite and reaches the eggs. Ignoring this interval reduces efficacy and may require repeated applications.
The recommended duration usually falls between ten and fifteen minutes. The exact time depends on the active ingredient:
- Permethrin‑based products: fifteen minutes of contact before rinsing.
- Pyrethrin‑based formulations: ten minutes of contact before rinsing.
- Dimethicone‑based shampoos: fifteen minutes, with emphasis on thorough saturation of all hair shafts.
Key steps for optimal results:
- Apply the shampoo to dry hair, ensuring complete coverage from scalp to tips.
- Massage gently to distribute the solution evenly; avoid vigorous scrubbing that could damage hair.
- Leave the product on the scalp for the stipulated time, using a timer to avoid under‑ or over‑exposure.
- Rinse thoroughly with warm water, then repeat the process after seven days to eliminate any newly hatched nymphs.
Failure to adhere to the prescribed exposure period may allow surviving lice to repopulate, leading to treatment failure. For children under two years, consult pediatric guidelines, as some products advise shorter contact times or alternative treatments.