Ammonia and smelling salts have long been used as a stimulant by NFL players as well as other athletes, though the risks that come with their use have been noted. Many boxing competitions, for instance, have banned smelling salts under the pretense that their use can mask serious injury.

The NFL has banned the use of smelling salts during games, citing an FDA warning concerning the safety of the substance. Here's what experts say about the effects and the risks.