OC (Oleoresin Capsicum) is the active ingredient in defensive sprays, also known as pepper extract. This natural pepper extract contains capsaicin, which causes intense burning, watery eyes and respiratory distress on contact with skin and mucous membranes. OC sprays are very effective for self-defense and temporarily incapacitating an attacker. The effects are short-lived but strong enough to give the victim time to escape or summon help.