To apply spinosad (Natroba®), start by shaking the bottle well. Apply as much as necessary -- up to a full bottle -- to cover the entire scalp and all of your hair. Make sure to cover the scalp completely, as missing any spots could allow the lice to survive. Leave the liquid on for 10 minutes, then rinse thoroughly with warm water.
Although medication is an important part of lice treatment, you must still treat the house in order to keep the lice from coming back. For example, in addition to applying spinosad, you will need to wash any recently worn clothing or bedding in hot water.
(Click Spinosad Dosage to learn more about the proper application of this product. This article also discusses how to protect your eyes and face during treatment.)