What is another name for a blister agent?

• A. Irritant
• B. Corrosive
• C. Toxin
• D. Vesicant

Answer: (D)

Blister agents are called vesicants because their defining effect is to produce vesication—blistering of the skin and mucous membranes. When a vesicant exposes the skin, it damages the epidermal layers and causes fluid-filled blisters to form as the tissue separates. This blistering can be delayed after exposure, which is a key clinical feature to recognize in hazmat responses.

This concept isn’t about general irritation, which is just surface inflammation without blister formation; nor about corrosives, which cause tissue destruction through caustic burns but aren’t defined by blistering. A toxin is a broad term for poisonous substances that can have systemic effects rather than the localized blistering pattern that defines vesicants. Vesicants include agents like sulfur mustard and related compounds, which specifically cause blistering on contact.