Vitamin B12 deficiency treatment depends on the cause and severity, but intramuscular injections are generally considered the most reliable first-line therapy. B12 injections (typically cyanocobalamin or hydroxocobalamin) bypass absorption issues in the stomach and intestines, making them effective for pernicious anemia and other malabsorption conditions. Injections are usually given weekly or monthly depending on the deficiency severity and underlying cause.
For milder deficiencies or when absorption is intact, oral supplements (tablets, lozenges, or liquids) can be effective, though they require adequate intrinsic factor for absorption. High-dose oral B12 may work through passive diffusion even when normal absorption is impaired. Sublingual or nasal formulations are alternatives, though evidence for their superiority is limited.
Dietary sources—including meat, fish, eggs, dairy, and fortified cereals—can prevent or manage mild deficiencies in people with normal absorption. Vegans typically need supplements or fortified foods since B12 occurs naturally only in animal products.
The underlying cause must be addressed: treating pernicious anemia requires ongoing injections; correcting dietary insufficiency involves education and supplementation; managing medication side effects may involve dose adjustment or switching drugs. Testing should confirm deficiency before starting treatment, as symptoms can mimic other conditions.
Treatment duration varies—pernicious anemia requires lifelong management, while dietary deficiency may be corrected with several months of supplementation followed by maintenance. Your healthcare provider should determine the best approach based on test results, the cause, gastrointestinal function, and individual circumstances.