Stimpak (Fallout: New Vegas)

Stimpaks function much the same as in Fallout 3, with one exception. If the player chooses to play in Hardcore Mode, stimpaks will heal over time (versus instantly) and will not heal crippled limbs. Limbs can only be healed by a doctor or with the use of items that specifically indicate limb healing in their information. (Including, but not limited to, hydra, a doctor's bag, weapon binding ritual, daturana and healing poultice) Teaching Jack in Red Rock Canyon Drug Lab with the new patch still sets the value at 25 instead of the normal patched merchants 75.

Crafting
In Fallout: New Vegas, stimpaks can also be created by using broc flower, Empty syringe and xander root with a Science skill of 70 at a workbench.