Summary Riot control agents are highly potent sensory irritants of relatively low toxicity that produce dose and time-dependent acute site-specific toxicity. These compounds have been referred to as transient incapacitating agents or as lacrimators, and in common parlance they are known as "tear gases". These compounds interact pharmacologically with sensory nerve receptors associated with mucosal surfaces and the skin at the site of contamination, resulting in localized discomfort or pain with associated reflexes. This biological response, e.g. ocular irritation, results in pain in the eye and excess reflex lacrimation and blepharospasm. Riot control agents have both civil and military applications and have been classified as either military chemicals or chemical warfare agents. Non-lethal or less lethal weapons have become increasingly popular for law enforcement use when confronting dangerous, combative individuals in the field, include riot control agents. Many incapacitating agents were developed during the Cold War. Oleoresin capsicum (OC) spray, an extracted resin from Capsicum pepper plants, was first developed in the 1970s as an alternative to CS (2-chlorobenzylidene malononitrile) and CN (chloroacetophenone) agents. Most recently, a synthetic form of capsaicin, PAVA (pelargonic acid vanillylamide), gained popularity as a defensive aerosol in the early 1990s. Chemical, pharmacological, and toxicological properties of PAVA are discussed in this paper.