Serum

Serum is used in Metal Gear Solid 3 to cure poison that inflicted on Naked Snake by enemies such as poisonous Scorpions and Tarantulas and other external causes such as poisoned weapons. Snake must only apply the Serum to cure himself of the poisoning - otherwise his health will slowly diminish until he dies.

Snake's Serum is useful for treating toxins from a variety of poisonous animals, such as the Cobalt Blue Tarantula, the Emperor Scorpion (whose venom is not actually lethal) and the Brazilian Wandering Spider. He should have it in abundant supply when fighting The Fear, as he can poison Snake by firing poisonous arrows from his crossbow.