A blister agent (or vesicant) is a chemical compound that causes severe skin, eye and mucosal pain and irritation in the form of severe chemical burns resulting in fluid filled blisters. Named for their ability to cause vesication, blister agent refers in common parlance to those agents which are developed for, or have been in the past utilized as chemical weapons, though some naturally occurring substances such as cantharidin fall under the same terminology. Exposure to blister agents is widely incapacitating, but often precipitates a delayed effect, with symptoms developing one to twenty four hours following the initial contact with the agent. Treatment for acute exposure is largely supportive, with the exception of Lewisite, for which an antidote is available. Overall lethality as a direct result of exposure is low, but increases with dose. Despite low overall lethality, blister agent exposure requires extensive supportive treatment, and can cause significant strain on medical systems. In some cases, blister agents have limited medical uses including for purposes of wart removal.