Do not immediately apply more medicine
If a few lice move slowly 8–12 hours after treatment, the medicine may still be working. If no dead lice are found or the lice seem as active as before, contact a healthcare provider before retreating.
Common reasons for failure
CDC lists several reasons a treatment may appear unsuccessful.
- The original finding was not actually head lice.
- Conditioner or a combination shampoo/conditioner was used before treatment.
- Directions, timing, or product amount were not followed.
- The lice may be resistant to that medication.
- The person was reinfested after successful treatment.
Know when to change course
Do not use different lice medicines at the same time, and do not use the same unsuccessful medication more than 2–3 times. A pharmacist or clinician can help select another option.
Health information notice
This article is educational and does not replace advice from your child's clinician or pharmacist. Always follow the current product label and seek professional help when you are unsure.