Try swapping your deodorant for an antiperspirant to help prevent wet spots from appearing underneath your arms and staining your favorite silk blouse. Most contain aluminum compounds that occlude sweat ducts and prevent perspiration from reaching the skin's surface (where it's exposed to bacteria that can cause odor). Drugstore brand Certain Dri contains a higher percentage of aluminum chloride than most other over-the-counter antiperspirants; apply it at night, and in a few days you should notice significantly less sweating. Your doctor can prescribe the stronger Xerac AC or Drysol. Whatever the level of protection, it will be more effective on bone-dry skin, says Loretta Ciraldo, MD, voluntary professor of dermatology at the University of Miami Miller School of Medicine, who tells patients to dry their armpits with a hair dryer (on the cool setting) before applying antiperspirant. For a more long-term solution, there's Botox. Underarm injections can cost up to $3,000, but you'll stay dry for at least three—and up to seven—months.