can a b12 injection cause diarrhea do injections Vitamin B12 Hydroxocobalamin (Vitamin B12): Uses, Alternatives,
Description
Vitamin B12 has not been shown to cause any harm, even at high doses[1]
We only absorb about 1 microgram of B12 at a time, though that number can vary based on the dose, says Caspero

J Diet Suppl
The NAD(+) precursor nicotinamide riboside enhances oxidative metabolism and protects against high-fat diet-induced obesity
SAR650984 directly induces multiple myeloma cell death via lysosomalassociated and apoptotic pathways, which is further enhanced by pomalidomide
Since the body cannot produce B12 on its own, it must be obtained through diet (found in animal products) or supplements, such as B12 injections
