|For the trait, see Fast Metabolism (trait).|
With the Fast Metabolism perk, the player gains 20% hit points when using stimpaks. In Hardcore mode, the multiplier increases the amount of healing per second making stimpaks an even better in-combat healing option. Players not playing on Hardcore mode may be better served by simply applying multiple stimpaks from their Pip-Boy rather than investing in the perk.
This perk also affects (adapted) alien biogel, super stimpaks, and the auto-inject versions of the stimpak. Despite not directly healing HP, Fast Metabolism will also improve the effectiveness of doctor's bags.