side effect from b12 injections Vitamin Effects MIC B12 Side Effects: Safety

Vitamin B12 is water-soluble and absorbed in the intestines

Surgical procedures or conditions that affect the gut, such as gastric bypass surgery or celiac disease, can prevent intrinsic factors from binding to B12 and prevent the body from breaking it down before absorbing the vitamin

Synergy is inferred from the individual mechanisms, not demonstrated in combination

Some patients feel as though they want more frequent injections, and occasionally we test levels to see if they are receiving adequate replacement, but Im not sure how strong the evidence is to support this. GPs should consider periodic vitamin B12 testing of higher-risk patients who take metformin, even if they dont display symptoms of deficiency, the UK medicines regulator said earlier this year