Possible allergic reaction to B12 injections?? : r B12_Deficiency Vitamin B12 deficiency can DAMAGE nerves if ignored , From numbness to memory lossknow the signs before its too late., , NCLEX favorite topic, Save Share Educate, #nursingstudents , That pins and needles feeling might be more than poor posture. When this feeling keeps coming back, it could point to an underlying health concern. , Conditions such as vitamin B12 deficiency, early How Soon Do You Feel Less Tired After a B12 Injection?