antidote

n. remedy; medicine that works against the effects of poison

An antidote is a substance which can counteract a form of poisoning.Sometimes, the antidote for a particular toxin is manufactured by injecting the toxin into an animal in small doses and the resulting antibodies are extracted from the animals' blood. The venom produced by some snakes, spiders, and other venomous animals is often treatable by the use of these antivenoms, although a number do lack one, and a bite or sting from such an animal often results in death. Some animal venoms, especially those produced by arthropods (e.g. certain spiders, scorpions, bees, etc.) are only potentially lethal when they provoke allergic reactions and induce anaphylactic shock; as such, there is no "antidote" for these venoms because it is not a form of poisoning, though anaphylactic shock can be treated (e.g., by the use of an EpiPen).
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Antidote /an·ti·dote/ an agent that counteracts a poison.antido´tal chemical antidote one that neutralizes the poison by changing its chemical [more]Antidote - Community and Resources

Noun
1. a remedy that stops or controls the effects of a poison
(synonym) counterpoison
(hypernym) remedy, curative, cure
(hyponym) atropine

n. antidote, remedy