Antidotes are administered to counteract the effects of some toxic materials (Table 8.9). The definition of an antidote is “any substance that nulls the effects of a poison on the spot and prevents its absorption or blocks its destructive action once absorbed.” The problem with antidotes is that there are only a few in existence and they do not work on all types of poisons(see Table 8.9). Another problem with antidotes is availability-an antidote must be given immediately after exposure to a poison or the victim may die anyway. Most EMS units do not catty antidotes for toxic exposures: by the time a person is taken to a medical center where the antidote may be available, it may be too late.