Antiperspirants: Their active ingredient — an aluminum salt — blocks sweat glands temporarily, preventing moisture from reaching the skin’s surface. They’re a great choice if you sweat a lot or live in a humid climate. (Theories that the use of aluminum salts can lead to Alzheimer’s disease have not been proven.)

Deodorants: These don’t stop sweat; instead, they use antiseptic ingredients, such as witch hazel and alcohol, to kill odor-causing bacteria on the skin. “People perceive them to be more natural than antiperspirants,” says New York City dermatologist Debra Wattenberg. Deodorants are a good pick if you sweat minimally.