What is the ruling on a fasting person using saline solution, vitamin injections, intravenous injections, and rectal suppositories?

Everything that is food or drink, or similar in meaning to them, breaks the fast. This includes intentional eating and drinking, and everything that enters the body cavity as nourishment or water, such as snuff ( سعوط ) and nutritional intravenous fluids.

Therefore, saline solution given intravenously is considered among the things that break the fast, because it enters the body cavity and the body benefits from it.

As for vitamin injections and non-nutritional intravenous injections (taken to energize the body, relieve pain, or lower fever), they do not break the fast. However, if they are nutritional, they do break the fast.

A suppository ( إلبوس شرجي ) does not break the fast because it is for treatment and is not in the meaning of food or drink.