Pepper spray, also known as OC spray (from "Oleoresin Capsicum"), OC gas, and capsicum spray, is a lachrymatory agent (a chemical compound that irritates the eyes to cause tears, pain, and even temporary blindness) used in policing, riot control, crowd control and personal self-defense, including defense against dogs and bears. Its inflammatory effects cause the eyes to close, taking away vision. This temporary blindness allows officers to more easily restrain subjects and permits persons using pepper spray for self-defense an opportunity to escape. Although considered a less-than-lethal agent, it has been deadly in rare cases, and concerns have been raised about a number of deaths where being pepper sprayed may have been a contributing factor. The active ingredient in pepper spray is capsaicin, which is a chemical derived from the fruit of plants in the Capsicum genus, including chilis.
Contributions by Mark Shaw, 126.96.36.199, and ClockworkSoul.