An antidote or antivenom used to neutralize or counteract the effects of a poison or venom.
From 'counter-' (against, to neutralize) and 'venom' (poison), from Latin 'venenum.' Medieval physicians created countervenom mixtures to combat snake bites and poisoning.
Ironically, many countervenoms are made from the same venom they fight—snake antivenoms contain a tiny bit of snake venom that trains your immune system to defend itself, essentially fighting poison with poison.
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