Injections while Fasting?
Muslimah..injection is allowed to be done during fasting for both as a treatment and insert nutrients, it is permissible with both inserting
through the muscle and through the veins. Because even if the liquid enters the abdomen, it is not through the usual channels.
However, if you know it can be felt up to the throat then as a precaution it is considered makruh, and do the treatment during the day.
Source: Fiqhul Mar’ah Al-Muslimah by Ibrahim Muhammad Al-Jamal