Benefits of Vitamin B12 Injections (and When You Actually Need Them)
B12 injections are useful — but they're not a wellness shot. Here's who actually benefits, and why oral B12 fails for some patients.
What B12 actually does
Vitamin B12 (cobalamin) is essential for red blood cell formation, DNA synthesis, and myelin — the insulation around nerves. A deficiency shows up as fatigue, brain fog, tingling in hands or feet, mood changes, and in advanced cases anaemia and neurological symptoms.
Because the body can store several years' worth of B12 in the liver, deficiency develops slowly. That's why it's often missed for years — the person feels a gradually 'off' version of themselves rather than a sudden change.
Who genuinely benefits from injections
Confirmed B12 deficiency on blood work, particularly with symptoms.
Pernicious anaemia (autoimmune loss of intrinsic factor).
Post-bariatric surgery or gastric/ileal surgery.
Long-term proton pump inhibitor or metformin use.
Vegan diet without consistent oral supplementation.
Age-related decline in gastric acid limiting absorption.
For most people without absorption issues, high-dose oral B12 (1000+ mcg/day) is as effective as injections. Injections shine when absorption is impaired or when levels need to be corrected quickly.
How the injection appointment works
A B12 injection at CurAge Santé is a short appointment. The Registered Nurse reviews your history, confirms recent B12 levels (blood work within the last 6–12 months for a first dose is ideal), gives the intramuscular injection (usually deltoid), and documents the visit.
A typical schedule for confirmed deficiency is weekly for 4–6 weeks, then monthly, then re-checking blood work at 3 months to individualise the maintenance interval.
Frequently asked questions
Do I need blood work before my first B12 injection?+
For anyone without documented deficiency, yes. This confirms the injection is medically appropriate and gives a baseline to guide future dosing.