Because B12 is an essential part of how your biochemistry works, it's not very common that it is actually B12 causing the side effects or reactions
Neither happened for me (thankfully) and I found easier ways to help my boys
I would definitely recommend this location
Establish a Sterile Field: Work on a clean, disinfected surface
[6] [3] [10] A mild deficiency may not cause any discernible symptoms, but moderate deficiency can cause various symptoms, such as feeling tired, lightheadedness, headaches, cold intolerance, pale skin, sore tongue, upset stomach, loss of appetite, hair and skin color changes, numbness or tingling (pins and needles) of the fingers and toes, and tinnitus, and vision, cognitive or psychological problems