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How often should you get B12 shots, and how much B12 should you inject per shot? We get these two questions often, which is why they also appear on our FAQ page.
The truth is, the exact vitamin B12 injection dosage for adults and children matters less than the frequency of the shots. Doctors often get this wrong. They start with 5–10 shots over a few weeks, then gradually space them farther apart, sometimes by months.
This is not the best way.
Most B12 Shot Dosage Advice Is Wrong
For example, one of our readers sent us this note from his clinic:
If you’re having trouble reading the image, the note says:
We are going to request a test for something called “Intrinsic Factor” on your next visit. If this test is positive then it means you definitely have Pernicious Anaemia and you will need to continue your injections every 3 months. If your test is negative it means we can review the need for the injections and it is likely that you do not need more. The 5 initial loading doses are usually all that is needed for long lasting protection. We would then simply check your blood once a year to make sure your levels of B12 have not fallen.
These instructions are terrible. One injection every three months is not sufficient for people with pernicious anemia. Nor do five—or even fifty—loading doses provide long-lasting protection for people with other B12 absorption issues. On top of that, checking B12 blood levels once a year is a very poor indicator of true B12 status.
Unfortunately, such vitamin B12 injection dosage and frequency advice is common. It is irresponsible and can lead patients with low B12 to lifelong nerve damage.
This scandal is the reason our operation exists. Despite the existence of such a simple treatment, doctors in the USA, UK, and other countries consistently deny it to patients with B12 deficiency and pernicious anemia. They don’t realize how deadly B12 deficiency can become, and believe they only need to keep patients’ B12 levels between 150–700 pmol/L. However, B12 levels can rise regardless of whether treatment is effective.
Best B12 Injection Dose and Frequency
So, what is the recommended B12 injection protocol?
If you’re using our product, our preferred vitamin B12 injection dosage for adults is 0.3 mL, once a day for at least three months in a row. Each vial contains 40 mg of B12. Once dissolved in 10 mL of saline, each 0.3 mL dose delivers 1.2 mg of B12, about 400–500 times the recommended daily allowance. It’s good insurance. You can’t overdose.
If you use another B12 injection kit (hopefully not cyano B12), aim for at least 1 mg of B12 per shot, which is plenty. You won’t absorb all of it, but such a high B12 injection dose ensures you have enough B12 circulating in your bloodstream at all times.
Better safe than sorry.
Why daily injections work better
Forget about the ‘vitamin B12 monthly injection dose’ your doctor prescribed. The key is little and often. In other words, smaller daily doses are better than infrequent higher ones. Your B12 shot frequency matters so much because B12 is water-soluble, so any excess is excreted within hours. The body can only retain so much.
Injecting daily helps maintain steady saturation of your cells. Daily B12 injections are especially crucial if you show neurological symptoms of B12 deficiency.
Why the three-month period matters
Red blood cells live for about 90 days. Only after three months of daily injections will all the abnormal cells have been replaced by healthy cells. Continue daily injections until symptoms stop improving, because some of them may not be fully reversible. Only then can you switch to every-other-day shots or test different doses or frequencies.
Note: We recommend the same vitamin B12 injection dose for adults and children. In both cases, each shot provides far more vitamin B12 than what the body needs. Again, B12 is harmless even at much higher doses, so it’s better to play it safe and inject too much rather than too little.
B12 injection dosage for pernicious anemia
How often should you have B12 injections for pernicious anemia?
We recommend starting with the same daily schedule for three months, until symptoms stop improving, and then starting to test. If moving to every other day doesn’t make symptoms worse, that frequency is likely enough. It’s a good idea to give that change three months as well. You can then try every three days. Only testing can tell you the answer, but a daily B12 injection schedule should be your starting point.
If you have pernicious anemia, make sure you’re using the methylcobalamin form of B12. It comes bundled with a valuable methyl group, which PA patients often lack. This methyl donor helps reduce homocysteine levels, addressing two problems at once. If you’d like to learn more about all forms of B12, we wrote extensively about them.
If you can’t get your doctor to prescribe daily methyl B12 injections, you can get them from us and take control of your health. This is what we’re here for. How much B12 is in a shot? With our methylcobalamin, the injection dosage is 1,200 μg per 0.3 mL syringe. This is a healthy vitamin B12 shot dose to aim for, even with other kits.
The weight loss trap
When readers ask us about vitamin B12 injection dosage and frequency for weight loss, we give the same answer every time: this is not a legitimate reason to take B12 shots. That’s not what they are for. They are meant to help people with B12 deficiency.
Don’t fall for the hype.
Takeaways: How Much and How Often
To wrap up, how much and how often can you take B12 shots?
In short, our recommended vitamin B12 shot dosage and frequency is around 1 mg per shot, injected daily for at least 90 days. Once symptom improvement plateaus, you can try less frequent schedules and monitor your body’s response. If symptoms creep back, revert to your previous B12 injection schedule. That’s how you find the sweet spot.
In short:
- Begin with daily shots for at least three months.
- Monitor your symptoms.
- Adjust as needed.
Good luck.