Painkiller

 is a deathstreak in Call of Duty: Modern Warfare 2. It gives the user double the normal health when they spawn for the third time without getting a kill. It only lasts for ten seconds before the player's maximum health returns to normal. While Painkiller is in effect, the player's screen is tinged red with a pill showing how many seconds are left in the deathstreak reward. When shooting a player with deathstreak, a small pill will appear below the crosshairs. This deathstreak replaces Juggernaut, but is a little less effective since it's temporary. In most game modes, the player will respawn away from the action, making this deathstreak useless though this perk can be useful if an enemy kill streak is in use such as a helicopter or AC-130, giving the user enough time to react and find cover. It is more helpful in crowded games like Free-for-All where players often spawn close to each other.

The extra health may confuse experienced players who know exactly how many shots are needed to kill a non-painkiller enemy causing them to instinctively stop firing before actually killing the painkillered player giving them a chance to recover and fire back.

Tips

 * Painkiller will prevent most one-hit-Kills, even from a sniper rifle bullet to the head in Hardcore (Minuscule Health). However, some weapons can still kill in one hit even with the added protection from Painkiller. Oddly enough, a silenced Intervention will not kill in one head hit (with Painkiller) while the FAL will. (Not true, Suppresed Intervention headshot is 50*1.5=75, the FAL has the same damage values for close range, and reduces to 35 at long range. Painkiller is 30*2=60. Player must have missed the head and hit the arm.)

Trivia

 * Painkiller may be a reference to the somewhat historically questionable origin story of the M1911 .45 caliber pistol. During the Filipino-American War, the under-armed Moro guerillas would often rush American soldiers, targeting the officers, armed only with machetes called Bolos. The officers' .38 Long Colt rounds would often hit but fail to immediately stop or kill the Moros who would continue attacking. It was rumored the Moro were taking drugs or painkillers which allowed them to continue fighting. However, there is little historic evidence that the Moro were actually taking drugs and the apparent "Painkiller" effect was a combination of the psychological effects of the Moro warrior culture, the underpowered .38 round, the nature of .38 revolvers at the time and the difficulty of making solid hits under stress. The larger .45 caliber semi-automatic pistol was rushed into service but was not used before the war ended.