Pain pills

Pain pills, unlike the First aid kit, will only give the user 50 temporary points of health when taken. When carried by Survivors, it is held on the Survivors right hip, probably on the belt.

Pills can be given to teammates by pressing the melee button (right click on PC or left trigger on 360). When not facing a teammate, pressing the melee button will allow you to use your melee attack against enemies.

Since the health from Pain Pills is only temporary, it will slowly decrease over time, dropping one point every few seconds until all the temporary health is gone. The pills you take will restore your movement speed and stop you from limping for as long as your total health is above (and including) 40%.

Keep in mind if when you take damage when both permanent health and temporary health exist, permanent health will be taken first. If while pain pills are active your actual health (read: permanent) drops below zero, your temporary health will continue dropping until it reaches 1%, where it will stay until you heal, take some more, etc.