Life In The Fast Vein
From: I. E.
If someone is sick and knows that he is going to have to eat on Yom Kippur, why not do so through intravenous? It's my understanding that since intravenous is not the normal way of eating, it's not technically a violation of the requirement to fast. If you tell me that intravenous is too big a bother or expense, isn't it true that a person must go to all lengths and expense not to transgress a negative commandment? So why don't sick people check into a hospital before Yom Kippur and 'eat' intravenously?
Dear I. E.,
The obligation to fast applies only on Yom Kippur itself. Therefore, there's no obligation to hook up to intravenous before Yom Kippur in order to fast on Yom Kippur. Once Yom Kippur arrives, it may be forbidden to hook up to intravenous. First, inserting a needle when not needed for health is prohibited because of causing a wound and spilling blood. Second, the intravenous may cause some unforeseeable health risk which the person is not required to take.
While on intravenous, Ill tell you a story. Once, a man on intravenous had an overwhelming desire for a glass of tea, and he convinced the doctor to administer it to him intravenously. When the tea began to flow, the man winced. "What's the matter," asked the doctor, "Too hot?" "No, too sweet."
- Iggrot Moshe Orach Chaim 3:90