Fasting, any type of injection Injections do not break the fast whether they are for feeding the person or just medicine. It does not matter if the injection was intravenous or underneath the skin. The Prophet, upon whom be peace, was cupped while he was fasting. However, if doing this weakens the fasting person, it is disliked. This is related by al-Bukhari and others.
Vivisection follows the same ruling as cupping.
At-Tirmizhi called it hassan sahih. There is a hadith that supports their opinion. Malik and Abu Hanifah hold that it breaks the fast because that water reaches the stomach. If he was aware that he was fasting, it breaks his fast, as if he would have drunk intentionally. It is similar to having a fly enter the mouth and proceed to the throat.