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, colloquially known as a med kit or health pack, is used to heal any damage the Survivors might take during a campaign. When carried by Survivors, it is held on like a backpack with no visible straps holding it.

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 in random places 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 extremely rare and should not be wasted.

In Left 4 Dead 2, there is the possibility no First aid kits will be available in the safe rooms. Therefore, it is highly recommended to use Pain pills and Adrenaline injectors whenever possible. Also the player has the choice to pick up a defibrillator instead, which can be used to revive dead team mates.

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 to do so is a waste of a first aid kit. In Left 4 Dead 2, Survivors are able to walk slowly and heal at the same time.

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.

Defibrillator
The Defibrillator is an item used only in Left 4 Dead 2. It can be used to revive dead teammates. The defibrillator replaces the health kit and is a one time use item. Its symbol is a lightning bolt.

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.

Adrenaline injectors
The Adrenaline injector (or the syringe) is included in Left 4 Dead 2. They use pain pills' slot and give you 25 temporary health (which adds to the maximum health, even extending it up to 125%), plus they make you immune to melee fatigue and the horde's slowing melee attacks, as well as increase your movement speed a great deal for a short period of time. The health added by the injector appears to drop slower than the health from pills. Injecting oneself appears to give one a tunnel vision effect. This item could become valuable at the end of a finale where Survivors are trying to get on the rescue vehicle but are constantly being slowed down by the horde. Same as the Pain Pills, Adrenaline Injectors can be given to teammates using the melee button.

Using the Adrenaline causes any sounds in the game to become Mono. This means that you can't really determine where somone/something is via sound.

Achievements
Dead Giveaway

Heal a fellow Survivor when your own health is below 10.

- If playing with a friend, have them shoot you until your health falls below 10, then heal your friend. If you're playing single player incapacitate yourself, then when an AI helps you up, quickly take out your med kit (the AI won't be able to heal you with it out) and heal the AI.

Pharm-Assist

Give pain pills to 10 Survivors.

- This is an easy achievement to get. Share your pills every chance you get, and if all the AI have pills, force them to take theirs by shooting them a few times then give them yours.

Field Medic

Heal 25 Survivors with a first aid kit.

- This one might be a bit difficult to achieve on single player since AI will occasionally heal themselves even if their health bar is green. Simply heal someone other than yourself 25 times.

Behind the Scenes
Early screenshots show that the First Aid Kit has a more boxlike shape, didn't look like it was made out of soft materials and had a carrying handle at one time. This design can be still be seen in the final version's First Aid Kit icon.

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!"
 * The design of the bottle is based off of Target brand Ibuprofen.
 * 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.
 * Since hitting the shelves, Left 4 Dead's "Pills here!" became an instant Internet phenomenon/meme, millions of fans claiming that the Survivors were addicted to these over-the-counter pain relievers (or "peelz") with an extensive focus on Louis and Bill, with Louis being portrayed as overly obsessed with them, and often repeating the phrase "grabbin' peelz".
 * In the game, Survivors swallow the entire bottle of pain pills at once. However, if someone were to do this in real life, they would likely die from an overdose soon after, or choke on the pills considering the Survivors don't ingest them with water. Plus, Ibuprofen usually takes around 20-30 minutes to actually start relieving pain, with a recommended dose of no more than 6 tablets per day, where in Left 4 Dead, the pills take affect immediately.
 * It is possible for a merciful Director to change a bottle of pills into a first-aid kit, even if a Survivor has already seen the pills.
 * Pain pills are attached to the Survivors' belts with no visible strap holding them. Likewise, the first aid kit stays on the their backs with apparently no straps keeping them on.
 * After using a first-aid kit, small bands of gauze will appear on the right arm and left thigh or the target, but disappear a couple seconds later.
 * The First Aid Kit, like the new P220 pistol in Left 4 Dead 2, had no walking animation, staying still on the screen when moving.
 * The health pack will be an avatar award for 360 users