- Eating or drinking deliberately. Allah the Exalted says: “Eat and drink until the white thread of dawn becomes distinct to you from the black thread; then complete the fast until night” (Q 2:187).
If, however, someone eats or drinks out of forgetfulness, that does not affect his fast. The Prophet ﷺ said: “Whoever eats or drinks while forgetting that he is fasting should complete his fast, for it is Allah who has fed him and given him drink.”
Among the acts that break the fast is letting water or the like reach the stomach through the nose—a procedure known as saʿūt—as well as receiving nutrient solutions through a vein or having blood transfused; all of these invalidate the fast because they provide nourishment.
The same ruling applies to nourishing injections, for they serve the purpose of food and thus nullify the fast. As for non-nutritive injections, the fasting person should also avoid them in order to safeguard his fast, following the Prophet’s instruction: “Leave that which makes you doubtful for that which does not,” and should postpone them until nighttime.