Can a Person Undergo Blood Transfusion and or Accept an Injection Which Nourishes His or Her Body During the Fast?
So when you transfuse blood, its taken as though as though it’s a sought of nourishment and food entering the body. So that breaks the fast.
Similarly if you put any food via the rise tube into the stomach that too breaks the fast, if it is parental feeding, it breaks the fast or if you inject anything which is in the form of nourishment then that breaks the fast. Even kidney dialyses as I mentioned earlier that if you take out blood from the kidney and you purify it and add into it few nutrients and chemicals and put back into the body that too breaks the fast.
Taking any injection whether intravenous whether intramuscular or subcutaneous if it does not contain nourishment, if it contains the form of nourishment, it breaks the fast. If its only for medicinal purpose, not containing nourishment then that does not invalidate the fast then the person can take that.
(Source - Dr Zakir Naik)