Certain Dri is the #1 over-the-counter brand that doctors recommend for their patients with excessive sweating, and is one of the original clinical antiperspirant brands. Certain Dri offers three levels of protection to help sufferers manage their excessive sweating. Certain Dri Prescription Strength Clinical Antiperspirant contains 15% Aluminum Chloride and is one of the strongest, most effective antiperspirants you can buy without a prescription. Aluminum Chloride is the strongest and most effective ingredient available and is the #1 doctor recommended active ingredient for hyperhidrosis. This Certain Dri formulation stops excessive sweating for up to 72 hours. PLEASE NOTE: this item is intended for people with the medical condition hyperhidrosis so it contains a strong active ingredient that may irritate the skin when applied incorrectly. It is important to apply sparingly at nighttime only to completely dry underarms. Do not use immediately after showering, shaving, or on broken and irritated skin.