Riot Control Agents (RCA’s) have been around for many years. Plutarch describes their use around 200 BC and the Japanese Ninjas used pepper spray to confuse their enemies. They were designed to cause a rapid onset of brief effects (< 30 minutes) and have a high safety ratio. All have some form of eye irritation, thus the name tear gas, and some cause coughing, skin irritation and vomiting. While there are many on the market OC (oleoresin capsicum, derived from hot peppers) and CS (tear gas, 2-chlorobenzalmalononitrile) are the most commonly used. Most open air exposure to vapors are relatively non-toxic and don’t require any decontamination. Exposure to the dry agents can usually be treated by fanning the arms or standing facing the wind. Contaminated clothing can be removed and skin irrigated with water, although in some cases water may make OC pain worse. There are commercially available decontamination products such as Bio Shield and Sudecon, although their effectiveness is difficult to judge and their composition is unknown. In general, exposed individuals should not rub their eyes, and blinking vigorously is thought to help by generating tears to wash away the agent. Some sensitive individuals may develop late respiratory symptoms relieved with bronchodilators. Capsaicin is not soluble in water, and even large volumes of water will not wash it off. One study  looking at five recommended treatments, including Maalox, lidocaine gel, baby shampoo, milk and water found that "..there was no significant difference in pain relief provided by five different treatment regimens. Time after exposure appeared to be the best predictor for decrease in pain."
1. Barry JD, Hennessy R, McManus JG. A randomized controlled trial comparing treatment regimens for acute pain for topical oleoresin capsaicin (pepper spray) exposure in adult volunteers. Prehosp Emerg Care. 2008;12(4):432–437. doi:10.1080/10903120802290786.
The Ask A Toxicologist Team