It doesn’t matter if a potential assailant is large, strong, or psycho, the effects of pepper spray on him will be instantaneous, and will last long enough (15 to 60 minutes) for you to get far enough way to get to safely or call for help. The active ingredient is called OC, short for oleoresin capsicum, which is derived from Cayenne peppers, some of the hottest in the world. Unlike mace or tear gas, which are irritants, the pepper spray effects cause inflammation when it comes in contact with mucous membranes (eyes, nose, throat and lungs). This can result in temporary blindness and instant inflammation of the breathing passages.

OC will also create an intense burning sensation on the surface of the skin. But despite its powerful and instantaneous effects, pepper spray does not cause any after-effects, so it’s safe to use. And since it is an inflammatory agent doesn't work like the irritant chemicals of tear gas, and it isn't vaporous, it won’t give off a lot of fumes. Pepper spray effects are proven to be one of the absolute best deterrents against vicious dogs and aggressive wild animals, as well as potential human attackers.