Healing items

Healing items are those used to restore lost Health, be it a temporary health boost or a permanent restoration.



Healing items can be found in ambulances or randomly throughout the level, but they are most often found inside of first aid stations. First aid stations can contain up to 4 bottles of pain pills, but there is also a chance they can contain first aid kits instead, depending on how the Survivors are doing and the difficulty level. First aid stations found in safe rooms always contain first aid kits.

Note: Sprays of the First aid Station have become widely available online and can look fairly convincing at a distance.

First aid kit
The first aid kit, also sometimes known as a med kit or health pack, is used to heal any damage the Survivors might take during a campaign.

First aid kits can always be found inside of safe rooms, and also during the finale of a campaign. They can also be found in first aid stations and anywhere else throughout the campaign, though this is very rare. On expert difficulty, most first aid kits found in the level itself will be replaced by pills. The only sure way to get health packs on expert is to grab one in the safe room or at the finale. Finding one in the level itself is rare and should not be wasted.

Usage
It takes 5 seconds to use the first aid kit to heal yourself or another Survivor, during which time you cannot defend yourself in any way. Instead of restoring a set amount of health, first aid kits will only restore 80% of the damage the Survivor has taken. For example, if a Survivor has taken 70% damage, using a first aid kit will add 56% (80% of 70) to the Survivor's health, bringing the Survivor to 86% health. This healing is not based on any temporary health a Survivor might have after taking pain pills, and will remove any extra health gained by them. Survivors healing after an incapacitation work on the same rules, and thus, always receive 80 health points. Please note that first aid kits can never bring a Survivor back to 100% health, and using more to try do so is a waste of a first aid kit.

See also: Health

As a weapon
A Survivor can use their melee attack while they are holding the first aid kit, though the only time you might consider doing so is if you were in the middle of healing yourself or another Survivor and you got attacked suddenly. If that happens, it would be best to use your melee attack to push the attackers away to give yourself time to switch to another weapon. Needless to say, using your melee attack while holding a first aid kit does the same amount of damage as any other melee attack, but it's easy to get caught up on trying to heal another Survivor (both the melee attack and healing another Survivor share the same button). Pistols would generally serve better in a (serious) fight.

Pain pills and Adrenaline injectors
Pain pills, unlike the First aid kit, will only give the user 50 temporary points of health when taken. Pills can be given to teammates by pressing the melee button (right click on PC or left trigger on 360 version). 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.

Adrenaline injectors (or syringes) are included in Left 4 Dead 2. They use pain pills' slot and give you 20-25 temporary health, plus they make you immune to melee fatigue and the Horde's slowing melee attacks for a short period of time.

Trivia

 * An interesting note is that in Team Fortress 2, another Valve game, pain pills make an appearance on an upgraded dispenser.
 * A poster in The Terminal advertises these specific pain pills, saying "Yes, we've got... Pills Here!"
 * Ibuprofen was apparently the most often used pain reliever during the development of Left 4 Dead, which may be why it is used as the label in-game. This is probably a reason why they appear in the Team Fortress 2 upgraded dispensers as well.
 * The design of the bottle is based off of Target brand Ibuprofen, with the only differences being the removal of the text and logo, and very minor differences in design to the right of the main section of the pill label.
 * Even whilst holding pain pills or a First-Aid kit, Survivors can still use their flashlight. This is odd as there is nowhere for the light source to emanate from.