Vesicant chemical-warfare agents

[GarryDrold]

Vesicants are chemical-warfare agents that cause blistering (vesicles) and include

Mustards, including sulfur mustard and nitrogen mustards
Lewisite
Phosgene oxime (technically an urticant and a corrosive agent rather than a vesicant, although it is classified as a vesicant)

These agents also affect the respiratory tract: mustards are predominantly type 1 agents, phosgene oxime is a type 2 agent, and Lewisite is a mixed agent.
Sulfur mustard has been variously described as smelling like mustard, garlic, horseradish, or asphalt. Lewisite may have a geranium-like odor, and phosgene oxime has been described simply as irritating. The perceptions of these odors are so subjective that they are not reliable indicators of the presence or identity of these compounds.
(See also Overview of Chemical-Warfare Agents.)