If exposure is through the skin or by ingestion, however, the pupils may be normal or only slightly to moderately reduced in size. In this event, correct diagnosis depends on recognizing the other symptoms of nerve agent poisoning. Respiratory exposure usually brings on symptoms in 2 to 5 minutes. Lethal doses kill in less than 15 minutes. Liquid in the eye kills nearly as rapidly as respiratory exposure.
Symptoms appear much more slowly from skin absorption.
Skin absorption great enough to cause death may take one to two hours to become fatal. Very small skin dosages sometimes cause local sweating and tremors but little other effects. Nerve agents are cumulative poisons. Repeated exposure to low concentrations, if not too far apart, will produce symptoms. The treatment of nerve agent poisoning includes the use of the nerve agent antidote.