How to tell if lice have been eliminated or not? - briefly
A thorough inspection with a fine-tooth comb should reveal no live lice or viable nits; if none are found and no new eggs appear after 7‑10 days, the infestation is considered cleared.
How to tell if lice have been eliminated or not? - in detail
To confirm that a lice infestation has been successfully removed, follow a systematic inspection and monitoring routine.
First, conduct a thorough visual examination. Use a fine-toothed comb on dry, clean hair, starting at the scalp and moving to the tips. Separate sections of hair and hold each strand taut. Look for live insects, which are tan to gray and move quickly, and for viable eggs (nits) that are firmly attached to the hair shaft within a quarter inch of the scalp. Any nits that can be easily slid off the shaft indicate they are no longer viable.
Second, repeat the combing process daily for at least seven days after the last treatment. Lice eggs hatch in 7–10 days, so a full week of negative findings confirms that no new insects have emerged. Record each inspection; a consistent absence of live lice and viable nits across all days is strong evidence of eradication.
Third, monitor for secondary signs. Absence of persistent itching, especially after washing and combing, suggests that no feeding insects remain. However, minor irritation may linger for a short period after treatment and does not alone indicate failure.
If uncertainty persists, consider a second professional evaluation. A trained technician can use a magnifying lens to detect any hidden specimens. In most cases, a combination of repeated meticulous combing, lack of viable nits, and cessation of symptoms provides definitive confirmation that the infestation has been eliminated.