Doctor

Doctors are one of the new features in Assassin's Creed II. Found on the streets of every city in black robes, they can either refill Ezio's Synchronization Bar for a fee, or sell him Medicine that can be carried and used later. They also sell him vials of poison for his Poison Blade.

Heal
Doctors can replenish all of your health by paying him a paltry sum of 50 florins. The price from the Doctor in Monteriggioni for his healing services, however, decreases as you renovate his stall.

Medicine
Doctors sell Medicine that acts as a healing item that can be carried with you anywhere you go. The number of Medicine vials you can carry at one time increases when you upgrade your Medicine Pouch from a Tailor.

Poison
Doctors sell Poison vials for a sum of florins. When Ezio asks Leonardo why Doctors would sell Poison, he replies that, when given in high doses, that which heals can kill. Poison is available only after upgrading Ezio's Hidden Blade with the Poison Blade.