Does insulin invalidate one’s fast? Also vitamin B12 injections.
In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
In general injections including insulin will not invalidate ones fast (unless such an injection that went through directly into the stomach). Therefore insulin is permitted to use during fasting.
Vitamin B12 injections however will be Makrooh (disliked) and should be avoided during fasting, as the purpose of these are to nourish the body.
For details on the laws of fasting see https://fatwa-tt.com/my-ramadhan-guide-1441-2020/
And Allah Ta’āla Knows Best
Mufti Arshad Ali
Darul Iftaa, Jaamia Madinatul Uloom (Trinidad)