This is what the wiki says about it:
Cure for Vampirism
If you?ve contracted the disease, you won?t become a vampire for three days. Until then, you can get rid of the disease with any Cure Disease potion or blessing.
After the first three days, the quest for a cure becomes more tedious. To begin the quest, visit any inn. The publican will send you to Morthal to speak to a man named Falion. That will start the quest Rising at Dawn.
However, if you are in one of the latter stages of Vampirism, the innkeepers will attack you on sight. Eventually, everyone will attack you. If this happens, you will need to feed in order to lessen the effects of your vampirism, making NPCs friendly again.
You can also cure your Vampirism by becoming a Werewolf through the Companions faction. However, once you contract Lycanthropy, you gain a 100% resistance to disease and cannot be re-infected with Sanguinare Vampiris. You can, however, become a vampire again if you cure your Lycanthropy.