Vesicant/Blister Agent Poisoning


The purpose of this document is to enable health care workers and public health officials to recognize when a chemical event has poisoned people by exposing them to vesicants/blister agents. Vesicants include distilled mustard (HD), mustard gas (H), lewisite, mustard/lewisite, mustard/T, nitrogen mustard, phosgene oxime, sesqui mustard, and sulfur mustard.


Vesicants, also referred to as “blister agents,” were the most commonly used chemical warfare agents during World War I. The most likely routes of exposure are inhalation, dermal contact, and ocular contact. Vesicants are highly reactive chemicals that combine with proteins, DNA, and other cellular components to result in cellular changes immediately after exposure.

Depending on the vesicant, clinical effects may occur immediately (as with phosgene oxime or lewisite) or may be delayed for 2 to 24 hours (as with mustards). Following exposure, 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 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. 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.

Signs and symptoms

The following is a more comprehensive list of signs and symptoms that may be encountered in a person exposed to a vesicant. Signs and symptoms are not listed in order of presentation or specificity. Also, partial presentations (an absence of some of the following signs/symptoms) do not necessarily imply less severe disease.

Respiratory signs and symptoms

  • Chest tightness
  • Clear rhinorrhea
  • Cough
  • Dyspnea (shortness of breath)
  • Hemoptysis
  • Nasal irritation/pain
  • Sore throat
  • Tachypnea

Dermal signs and symptoms

  • Blisters (within 1 hour with phosgene oxime, delayed for 2 to 12 hours with lewisite, delayed for 2 to 24 hours with mustards)
  • Erythema (immediate with lewisite and phosgene oxime, may be delayed for 2 to 24 hours with mustards)
  • Immediate blanching (phosgene oxime)
  • Itching
  • Necrosis and eschar (over a period of 7 to 10 days)

Ocular signs and symptoms

  • Blindness
  • Blurred vision
  • Corneal ulceration
  • Conjunctivitis
  • Eyelid edema
  • Eye pain/burning
  • Lacrimation
  • Photophobia

Cardiovascular signs

  • Atrioventricular block and cardiac arrest (with high-dose exposure)
  • Hypotension (with high-dose exposure to lewisite)

Gastrointestinal signs and symptoms (prominent if ingestion is a route of exposure)

  • Abdominal pain
  • Diarrhea (sometimes bloody)
  • Hematemesis
  • Nausea and vomiting

Central nervous system signs and symptoms (with exposure to high doses)

  • Ataxia
  • Coma
  • Convulsions
  • Tremors

Hematological signs and symptoms

  • Anemia
  • Bleeding/hemorrhage
  • Bone marrow supression
  • Increased susceptibility to infection
  • Leukocytopenia
  • Thrombocytopenia

Laboratory findings suggestive of vesicant exposure

Although it is a nonspecific finding, leukopenia can indicate vesicant exposure. It usually begins 3 to 5 days after exposure. With a white blood cell count < 500, the prognosis is poor.

Differential diagnosis

  • Barbiturates
  • Bullous pemphigoid
  • Chemotherapeutic agents
  • Carbon monoxide
  • Other chemical burns (such as with strong acids, bases, or corrosives)
  • Pemphigus vulgaris
  • Stevens-Johnson syndrome
  • Staphylococcus scalded skin syndrome
  • Toxic epidermal necrolysis

Note: The actual clinical manifestations of a vesicant exposure may be more variable than the syndrome described above.

Page last reviewed: April 4, 2018