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’re also on our FAQ page.
Your actual vitamin B12 injection dosage, for adults as well as children, doesn’t matter as much as how frequent the shots are. Unfortunately, doctors often don’t get it right. They start with 5-10 shots over the course of a few weeks, and later begin to schedule them farther and farther from each other. Sometimes it can be months between them.
As an example, here’s a note that one of our readers received and sent to us:

This is not nearly enough. One injection every three months is not sufficient for those with pernicious anemia, nor are five (or fifty, for that matter) loading doses enough for long-lasting protection for those who have other B12 absorption issues. Plus, checking the blood once a year for B12 levels is a very poor indicator of true B12 status.
As a result, many B12-deficient patients end up with lifelong nerve damage.
This scandal is the reason our organization is alive. Despite the fact that such a simple treatment exists, doctors in the USA, UK, and other countries consistently deny access of it to patients with B12 deficiency and pernicious anemia. They simply can’t grasp how deadly B12 deficiency can become, and think they simply need to keep the B12 levels of patients within the 150-700 pmol/L range. This is not that easy, because even when supplementing, B12 levels will rise regardless of therapeutic effectiveness.
Below are the correct vitamin B12 injections dosage and frequency.
B12 Injections Dosage & Frequency
If you use our injectable B12, our recommended vitamin B12 injection dosage for adults (in ml) is 0.3, once a day for at least three months straight. Our vial contains 40mg of B12 that you dissolve in 10ml of saline. This means that each 0.3ml syringe will give you 1.2mg (1,200μg) of pure methyl-B12, which is around 400-500 times the recommended daily allowance. It’s a good insurance policy, and don’t worry – you can’t overdose.
If you use another B12 kit (hopefully not made of cyanocobalamin B12), you’ll have to calculate how much B12 it nets you. Aim for around 1mg of B12 per shot, which is plenty. You probably won’t absorb all of it, but this ensures you’re getting enough B12 to circulate in your bloodstream around the clock. Better safe than sorry.

But, why inject daily?
Forget that “vitamin B12 monthly injection dose” that your doctor prescribed.
The secret is little and often. It’s better to inject smaller doses on a regular basis, rather than injecting mega-doses infrequently. Your B12 shots frequency is more important than the dose, because B12 is water-soluble, so any excess will be urinated within hours. The body can only retain so much of it, so you’ll want to inject often to make sure you’re constantly saturating your stores and cells. Start with daily injections, especially if you show neurological symptoms, which indicate an advanced B12 deficiency.
Now, why is a minimum of three months crucial?
The lifespan of your red blood cells is 90 days. Only after 90 days will all the malformed cells have been replaced by healthy ones. So keep injecting daily, until symptoms stop improving (because some of them may not be completely reversible). Only then can you do every-other-day-shots, and continue testing from that point.
By the way, we recommend the exact same vitamin B12 injection dose for adults and children alike. In both cases, you’ll be taking hundreds of times more B12 than what the body needs. But again, B12 is harmless even in mega doses, since any excess is flushed out. Therefore, it’s better to play it safe, and inject too much rather than too little.
What About Pernicious Anemia?
How often should you have B12 injections for pernicious anemia? We recommend to begin with the same three-month daily schedule, until symptoms stop improving, and start testing from there. If you reduce the frequency to every other day, and symptoms don’t get worse after a few months, then the frequency is likely sufficient.. Then you can test every-three-days. Only testing will give you the answer.
But, again, a daily B12 injection frequency should be your default starting point.
If you have pernicious anemia, make sure you’re getting the methylcobalamin B12 form. It comes bundled with a valuable methyl group, which pernicious anemia patients often lack. The methyl donor will help reduce your homocysteine levels, thus solving two problems at once. We’ve written extensively about the different forms of B12.
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? Again, with our methylcobalamin, injection dosage will be 1,200μg per each 0.3ml syringe. This is a great vitamin B12 shot dose to aim for, even if you use other brands.
B12 Injection Dose For Weight Loss?
What’s our suggested vitamin B12 injection dosage for adults in ml for weight loss? Well, if you’re taking B12 shots primarily to lose weight (or for “energy”), then don’t.
This is not the point of taking B12 shots.
Summary: How Much & How Often?
So, how much and how often can you take B12 shots? To summarize, our recommended vitamin B12 shot dosage and frequency is around 1mg of B12 per shot, injected daily, for at least 90 days. Once symptom improvement plateaus, you can experiment with less frequent schedules – consider trying every other day – and monitor how your body responds. If symptoms creep back, revert to your previous B12 injection schedule.
In short:
- Begin with daily shots for at least three months.
- Monitor your symptoms.
- Adjust.