You should contact your GP if: You have been found to have elevated B12 levels on blood tests, particularly if levels exceed 1000 ng/L (approximately 740 pmol/L, though laboratory reference ranges vary) and you are not taking high-dose supplements You develop new symptoms after starting B12 supplementation, including persistent skin rashes, significant gastrointestinal disturbance, or unexplained symptoms You have underlying liver disease, kidney problems, or blood disorders and are considering B12 supplementation You are taking B12 supplements without medical supervision and have not had your levels checked, particularly if taking doses exceeding 2000 micrograms daily You experience symptoms that might indicate underlying disease, such as unexplained weight loss, persistent fatigue, jaundice, or abdominal swelling Call 999 or go to A&E if you develop severe allergic reactions following B12 injections, including difficulty breathing, facial swelling, or widespread rash, as these may indicate anaphylaxis, though this is extremely rare

If left untreated, it can lead to Heart palpitations and shortness of breath Weakness, tiredness, or lightheadedness Pale skin Vision loss Constipation, diarrhea, loss of appetite, or gas A smooth tongue Depression Memory loss Behavioral changes Numbness or tingling Muscle weakness Problems walking not trying to give you the wobbles here!), low levels of B12 can be linked to the development of pernicious anemia, dementia, or osteoporosis
Each community has its own specific guidelines for safe disposal, so its important to follow your local regulations
UK guidance recommends hydroxocobalamin 1mg intramuscularly with dosing frequency determined by presence of neurological involvement
This was painful and caused my leg to jerk and I pulled out the needle without thinking