A drug or other agent that produces blisters. Vesicants are highly active corrosive materials even at extremely low concentration. Additional Info: One of the most familiar examples of a vesicant is called mustard gas, which was used as a chemical warfare agent in World War I and the Iran-Iraq war. Mustard gas is a trivial name for 1,1'-thiobis(2-chloroethane), also known as bis(2-chloroethyl)sulfide or HD. Certain chemically related species are collectively referred to as mustards. These agents can be quite deadly as they have a high solubility in lipids (fatty tissues). Symptoms of exposure to mustard gas include conjunctivitis, blindness, cough, edema of the eyelids, and erythema or necrosis of the skin. When inhaled, this can severely and irreparably damage the respiratory tract. And to add extra insult to injury, mustard gas is also a carcinogen. Vesicants have other uses besides chemical warfare; in these cases the vesicating properties are an undesirable/ unwanted side effect or symptom. For example, some chemotherapy drugs are mild vesicants as are a variety of industrial useful chemical intermediates. MSDS Relevance: The MSDS should warn if the material is a vesicant. Avoid the use of vesicants if at all possible. If a vesicant must be used, do so with appropriate controls such as a fume hood to minimize exposure and be certain to wear personal protective equipment (PPE) such as goggles, face masks, respirators, aprons, gloves etc. Do not rely on odor to warn you of possible exposure, vesicants can produce harmful effects at concentrations below the odor threshold. See also: lachrymator, Poison, Toxic