Definition of Vesicant

Vesicant: A substance that causes tissue blistering. A blister agent. Also called a vesicatory.Vesicants are highly reactive chemicals that combine with proteins, DNA, and other cellular components to result in cellular changes immediately after exposure.

Vesicants can be used as agents of chemical warfare, as was the case in World War I, or as agents of terrorism. Vesicants include distilled mustard (HD), mustard gas (H), lewisite, mustard/lewisite, mustard/T, nitrogen mustard, phosgene oxime, sesqui mustard, and sulfur mustard.

The most likely routes of exposure are inhalation, dermal contact, and ocular contact. Depending on the particular vesicant, clinical effects may occur immediately (as with phosgene oxime or lewisite) or may be delayed for 2 to 24 hours (as with mustards).

The amount and route of exposure to the vesicant, the type of vesicant, and the premorbid condition of the person exposed will contribute to the time of onset and the severity of illness as well as the treatment. For example, ingestion of a vesicant leads to gastrointestinal symptoms more prominent than those that would result from inhalation exposure to the same dose and type of vesicant.

Following exposure to vesicants, the most commonly encountered clinical effects include dermal (skin erythema and blistering), respiratory (pharyngitis, cough, dyspnea), ocular (conjunctivitis and burns), and gastrointestinal (nausea and vomiting). The ensemble of the signs and symptoms due to a vesicant has been referred to as the toxic sydrome by the Centers for Disease Control and Prevention (the CDC).