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
NAD+, on the other hand, is a critical coenzyme involved in DNA repair, energy production, and cellular health
The NIH Office of Dietary Supplements and the American Academy of Family Physicians identify the following groups as most vulnerable: Adults over 50 Age-related decline in stomach acid production reduces the ability to release B12 from food proteins
Intramuscular vs Subcutaneous B12 Injections Intramuscular or Subcutaneous B12 Injection
With most drugs in psychiatry, though, short half-lives do not necessarily translate into earlier benefits, and where higher levels need to be attained sooner than can be attained by waiting for 5 half-lives, this is achieved by administering higher initial (loading) doses, or by crowding earlier doses and then spacing them out into the recommended dosing intervals
