Prodromal stage (N-V-D stage): The classic symptoms for this stage are nausea, vomiting, as well as anorexia and possibly diarrhea (depending on dose), which occur from minutes to days following exposure. The symptoms may last (episodically) for minutes up to several days.
Latent stage: In this stage, the patient looks and feels generally healthy for a few hours or even up to a few weeks.
Manifest illness stage: In this stage the symptoms depend on the specific syndrome and last from hours up to several months.
Recovery or death: Most patients who do not recover will die within several months of exposure. The recovery process lasts from several weeks up to two years.