The healing spray was a first-aid item utilized by both the Militaires Sans Frontières and the Diamond Dogs in late 1974-March 1975 and 1984, respectively. The various members, including their leaders (Big Boss and Venom Snake, respectively), utilized these sprays if they sustained significant injuries. When used, they spray them across the chest, which has the user experience a slight amount of pain before being fully healed.
Behind the scenes
The healing spray was an item that appears in both Metal Gear Solid V: Ground Zeroes and Metal Gear Solid V: The Phantom Pain. The player can access the item if the player had sustained severe injuries that aren't either a dislocated arm or a dislocated leg. The function and design of the healing spray resembles the First Aid spray from the Resident Evil series.