Certain DRI antiperspirants are applied to the armpits before sleeping. That's because the active ingredient works better while sleeping to stop perspiration throughout the day. It is not going to wash the next day, even after bathing or showering. Apply a small amount of the completely dry armpit. Certain DRI are applied moderation only a few strokes under each arm. To reduce the risk of irritation, make sure armpits are completely dry before applying. For adequate deodorant protection, Certain DRI strength All day clinical antiperspirant + deodorant can also be applied in the morning for an extra layer of freshness and protection.