Hydra

 is a consumable item in Fallout: New Vegas.

Characteristics
Hydra is similar to a Doctor's Bag in that it restores limb damage, however Hydra slowly restores all damage over time (60 sec) unlike the Doctor's Bag, which takes effect immediately. In hardcore mode, Hydra is superior to the Doctor's Bag, which only partially heals a single damaged limb, or heals all limbs for a tiny amount. However, Hydra carries a 10% addiction rate. Like any other drug in the game, it can turn into an addiction where preventative measures are needed to stop withdrawal such as Fixer or a visit to a doctor. Hydra can be crafted, can occasionally be found in first aid boxes or bought from chem vendors. You can teach Jack to make it if you have enough skill, but he is the only vendor who routinely stocks it. When crafted over a campfire, you will need 75 Survival skill, Cave fungus (5), Night Stalker Blood (3), and Radscorpion Poison Gland (2). Cave fungus is extremely rare, and even finding enough to use this recipe once in an entire playthrough is unlikely, unless you are thorough about looting Caesar's troops, who have a rare chance of having one.