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 Prescription Strength Clinical Antiperspirant contains 12% 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.