can u overdose on b12 injections Symptoms if You Take Too Much Vitamin B12 Shots & B12 Injections:

Allergic Reactions and How to Handle Them Allergic reactions to B12 injections are rare but can occur

Vitamin B12 is not produced naturally in the body and must be obtained through diet or injections

Pernicious anemia is a chronic condition characterized by the inability to absorb vitamin B12, leading to deficiency and related complications. Other issues like problems after stomach surgery or diseases like Crohns also might need Vitamin B12 injections

Fish and shellfish: Fish such as salmon, trout, and haddock, as well as shellfish such as clams and mussels, are all rich in vitamin B12

If you are having private injections on top of an NHS schedule, the combined frequency may be higher than either provider realises, which is worth flagging to both