Directions: apply thoroughly to DRY HAIR or other affected area. For head lice, first apply behind ears and to back of neck, allow product to remain for 10 minutes, but no longer, use warm water to form a lather, shampoo, then thoroughly rinse, check daily for any lice/nits that you missed, a second treatment must be done in 7 to 10 days to kill any newly hatched lice, if infestation continues, see a doctor for other treatments. All Perrigo products must meet approved specifications for identity and strength prior to release for public use. Individual will vary in the way they respond to the same dose of a single drug. The difference in response can result from a number of factors responsible for altering the drug effect that include genetics, disease, age and use of other drugs at the same time. We would like to thank you for the opportunity to address your concern. As you may already know, we are required by the Food and Drug Administration (FDA) to obtain as much information as possible on adverse events associated with the use of our products. In order for us to better understand the events that occurred and file a complete report, we are asking for you to contact us. Please contact us and use the case number 666031 as a reference for this issue. We can be reached by phone at 1-866-634-9120, Monday through Friday 7:30am - 5pm ET. If we do not hear from you within two weeks, we will consider this matter closed.