Botulinum Toxin (Botox)
What It Is: An injectable drug that blocks overactive nerve impulses to reduce muscle activity.
What It's Approved to Treat: Excessive underarm sweating, overactive bladder, crossed eyes, muscle spasms, chronic migraines
Common Off-label Uses: Severely cold hands, premature ejaculation, depression
Botox may be best known for smoothing and preventing wrinkles, but the manufacturer, Allergan, holds almost 800 additional patents for the drug's potential uses, including those mentioned above [source: Sifferlin]. The neurotoxin is derived from a bacterium known as Clostridium botulinum, which can cause paralysis — and even death — if it's consumed in contaminated food. But when it's administered in small doses, it can cause muscles to relax. That mechanism of action is what makes it an effective wrinkle preventer, an overactive bladder treatment (it prevents involuntary contractions that can cause the feeling of urgency).
As far as depression, a 2014 study published in the Journal of Psychiatry revealed that because facial expressions are part of the brain circuitry related to mood, inhibiting muscles in the face may prevent people from making expressions associated with negative emotions.
No matter how it's used, however, Botox does come with a long list of possible side effects including muscle weakness, drooping eyelids and double vision if the drug spreads from the injection site to other parts of the body [source: Sifferlin].