A wonder of pre-War science, stimpaks are syringes filled with a mixture of healing agents and stimulants, allowing the user to boost their own body's natural regenerative functions. In most cases, it leads to an almost instantaneous regeneration of wounds. Stimpaks can also be used to treat physical conditions, such as a heart condition, but only temporarily. The syringe is typically equipped with a gauge for quickly identifying the state of the contents and can be used either in an intravenous or intramuscular fashion. The basic stimpak is designed for use on minor wounds, as the soup of healing medication is ineffective at treating major trauma.
Stimpaks are a type of hand held medication used to healing the body. The item consists of a syringe for containing and delivering the medication and a gauge for measuring the status of the stimpak's contents. When the medicine is injected, it provides immediate healing of the body's minor wounds, delivering between 30-90 hit points per injection, dependent on the level of the player's Medicine skill.
Additionally, it can be used to heal crippled limbs by injecting it directly into the affected limb - via the PipBoy interface. When used on a limb it heals a relatively high amount of damage on the limb, but slight healing on the body. Conversely, when used on the whole body, a relatively high amount of damage on the whole body is healed, but the limbs are healed only slightly.
↑ 1.01.1Vault Dweller's Survival Guide p.5-19: "A stimpak (short for Stimulation Delivery Package) contains many healing chems. A soup of healing medication, if you will. By injecting the Stimpak, you drastically increase your own recuperative functions and restore lost hit points almost instantly."
↑Fallout Official Survival Guide p.124: "Stimpak: The stimpak is an autoinjector loaded with a variety of healing medications and stimulants. Injecting yourself or another character will increase your natural healing ability and give you an immediate Hit Point boost."
↑The Lone Wanderer: "Here, take some Stimpaks. That should get him through." Madison Li: "Yes, this looks to be enough. He'll need medical attention once we've reached the Citadel, but this will get him there. Thank you. Give me a moment, and we can continue." (Madison Li's dialogue)