For The Resident Evil CODE: Veronica item, see Serum (Code: Veronica). For The Resident Evil 7: Biohazard item, see Serum (RE7).
"There's just enough for one dose."
A serum is mostly an antidote to a poison, although its effect and purpose can vary depending on the game.
- In the original Resident Evil and its source ports, the Serum has a number of unique effects. It is the only thing that will cure Yawn's poison during the first encounter (using Blue Herbs won't cure it). The Serum can also cure any conventional poison status effects (such as from Webspinners).
- In addition, the Serum will also make the player completely immune to Yawn's poison for the rest of the game, whether they had the Serum administered by Rebecca/Barry or they kept the Serum and used it themselves after failing to save Richard. If the player somehow avoids getting poisoned in the first encounter, they will not be immune to Yawn's poison during the second, though Blue Herbs will work this time.
- If Jill was poisoned but did not sustain significant damage, she must collect the serum herself.
- If Jill was poisoned and sustained damage, she will fall unconscious and Barry will collect it for her. She will regain consciousness in the 1F chemical storage room.
- If Chris is poisoned, he will lose consciousness and the player will take control of Rebecca, who must collect the serum for him.
- In the original version, if Chris decides not to take Rebecca with him after meeting her in the chemical room, she will automatically take him back there and administer the serum.