The First-aid spray acts as an instant continue option in Resident Evil: The Darkside Chronicles.
"Displaying remaining first aid sprays.First aid sprays are used automatically."
The first aid spray in The Darkside Chronicles behaves similarly to that of The Umbrella Chronicles, it is automatically used when the player dies in a chapter. Each chapter but the secret stage has one first aid spray in the environment.
Even if the player is revived by the first aid spray, the No-continue Clear bonus in the Results screen will still be given.
If an ally character dies, such as Sherry, the spray will not be used even if there is one available and it will instead head the player onto the Game Over screen as if no spray was obtained. The only way to see if a spray is available is by pausing the game and going into the status menu.