Blister agent toxicity

Author: Vanessa Ngan, Staff writer. Minor revision 22 February 2014.

Blister agents are one of the most common chemical warfare agents. Sulphur mustard was used extensively during World War I and then more recently in the Iran-Iraq War (1980-1988). The most apparent toxic effect of blister agents is the damage they cause to skin. They produce slow-healing skin lesions which can blister, ulcerate and promote secondary infections. These blister agents are also called vesicants.

Classification and chemical properties of blister agents

There are four main blister agent chemicals:

The letter/numbers following the chemical name is the military designations given to the blister agents.

The following table displays some chemical properties of the blister agents.

LewisiteSulphur mustardNitrogen mustardPhosgene oxime
Physical form Oily liquid Oily-textured liquid, gaseous vapour, solid Oily-textured liquid, gaseous vapour, solid Liquid, solid
Characteristic odour Geraniums Garlic, onions, mustard, or odourless Fishy, musty, soapy, fruity Irritating, disagreeable odour
Colour Colourless in pure form. Amber to black in impure form. Clear to yellow or brown Clear, pale amber or yellow Colourless in solid form. Yellow-brown in liquid form.

What are blister agents used for?

All these blister agents were produced as potential chemical warfare weapons. Only lewisite and sulfur mustard have ever actually been used at war. Some nitrogen mustards were designed to remove warts and treat cancers, but have now been replaced with safer and more effective agents. Historically, sulfur mustard has been used to treat psoriasis but has no medical use today.

Blister agents are relatively easy to produce and large stockpiles of these agents may be present in several countries. There is always the underlying threat that they can be used in a terroristic attack.

What are the signs and symptoms of blister agent toxicity?

Signs and symptoms differ slightly between the different blister agents.


Signs and symptoms occur immediately after exposure.

Skin effects:

Other system effects:

Sulfur mustard

Signs and symptoms do not usually occur immediately after exposure. Depending on the severity of the exposure, symptoms may not occur for up to 24 hours. People who are more sensitive to sulfur mustard may show signs and symptoms earlier. Often people may not know immediately that they have been exposed, because sulfur mustard may not have a smell or have a smell that causes alarm.

Skin effects:

Other system effects:

Nitrogen mustard

Signs and symptoms usually do not occur immediately but depend on the severity of the exposure. Symptoms may not occur for several hours after exposure.

Skin effects:

Other system effects:

Phosgene oxime

Signs and symptoms occur immediately after exposure.

Skin effects:

Other system effects:

What is the treatment for blister agent toxicity?

The most important factor in the treatment of blister agent toxicity is removing the blister agent from the body. Remove and seal off in a double plastic bag any contaminated clothing. Seek emergency medical attention immediately. Lewisite is the only blister agent with a known antidote. Exposure to blister agents is not usually fatal if patients receive immediate supportive medical care to minimise the effects of exposure.

Sulphur mustard was heavily used in the Iran-Iraq War and currently there are about 30,000 victims still suffering from the late effects of the agent. Chronic obstructive lung disease, lung fibrosis, recurrent corneal ulcer disease, chronic conjunctivitis, abnormal pigmentation of the skin, and several forms of cancer, are just some of the long-term effects from their exposure.

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