March 5, 2024/Nutrition

Vitamin B12 Injections: What They Can and Can’t Do

If you have low B12 or a true deficiency, these shots can work wonders

vitamin b12 shot in foreground with vials in background

When you think of vitamins, what comes to mind? Maybe you imagine a leafy, veggie-laden salad or some other healthy, nutrient-rich food. Maybe your mind turns to cartoon-shaped chewable tablets or the many selections in the supplement aisle. But what about injections?


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If you have a low vitamin B12 level, getting a boost in the form of injections or pills can go a long way toward improving your health and overall well-being.

But if your B12 level is normal? Well, don’t fall for the hype that they’ll magically help you shed pounds or give you Tasmanian Devil-like energy levels.

Let’s dig deeper into what vitamin B12 injections are, whether they work and who should — and shouldn’t — look into them.

What are vitamin B12 shots?

Vitamin B12, or cobalamin, is a water-soluble vitamin that helps your body produce red blood cells and DNA. It’s also important for healthy brain function and keeping your energy levels high.

But having a low B12 level or a vitamin B12 deficiency can cause physical, neurological and psychological issues. In this case, your healthcare provider will recommend supplementation to help get your level where it should be. 

“If your B12 level is found to be below normal, replacing that vitamin B12 is very important,” explains family physician Kenneth Goodman, MD. “Vitamin B12 shots or B12 pills will be essential for your health.” 

Vitamin B shots are injected into your muscle or deeply under your skin, usually in an area like your upper arm or thigh. To start, you may need them every day or every other day. But as your B12 level rises, you’ll be able to get them more infrequently.

“Depending on what’s causing your low B12 level, you may only need vitamin B injections until your level gets back to normal,” Dr. Goodman says, “though some people require them for the long term.” Your healthcare provider will make recommendations based on your B12 level, age, diet and overall health.

The benefit of vitamin B12 injections

Getting vitamin B12 injections to raise your B12 level to where it should be often improves symptoms like:

  • Blurred vision.
  • Depression.
  • Difficulty walking.
  • Dizziness.
  • Fatigue and generalized weakness. 
  • Irritability.
  • Loss of appetite.
  • Numbness and/or tingling.
  • Memory trouble.

If left untreated, vitamin B12 deficiency can lead to severe problems, including neurological (nervous system) damage that can’t be reversed.

How do you know if you need vitamin B12 shots?

Vitamin B12 shots can often undo symptoms of a low vitamin B12 level — but the issue is that you might not have any idea that your B12 levels are low to begin with.

“Because B12 levels aren’t checked during routine blood work, a deficiency can go undetected for years,” Dr. Goodman notes. Plus, the symptoms of low B12 can be very subtle, or they may be confused for symptoms of other conditions.

Low vitamin B12 levels are more common among those who: 

  • Are over age 65.
  • Keep a strict vegan or vegetarian diet.
  • Have had weight loss surgery.
  • Have a gastrointestinal condition like gastritis or Crohn’s disease.
  • Take certain types of medications, including heartburn medicine.


If you’re experiencing troubling symptoms or believe you’re at high risk for a deficiency, raise these concerns with a healthcare provider, who may decide that you should be tested.

Do vitamin B12 injections help with weight loss?

If you have low B12 and are battling fatigue and/or depression, raising your B12 level back to normal can ease these symptoms and help you feel more energetic. This could ultimately lead you to lose some weight. But B12 shots themselves aren’t associated with weight loss.

And if your B12 levels are normal, getting B12 injections isn’t going to do anything. Studies show that high vitamin B12 levels may be associated with a lower risk of having obesity, but, again, that doesn’t mean that getting vitamin B12 shots will help you lose weight. 

“If your B12 level is normal, there is little evidence to support that they actually work for these purposes,” Dr. Goodman states.

Will vitamin B12 injections give you more energy?

Some people pursue vitamin B12 shots because they believe that doing so will increase their energy levels. If you have low B12, this is likely true — but if you don’t have low B12, don’t count on it.

“Taking additional B12 hasn’t been found to be of benefit,” Dr. Goodman clarifies.

Other sources of vitamin B12

Vitamin B12 injections are far from the only way to get vitamin B12. In fact, most people are able to get enough vitamin B12 through diet alone. It’s found in lots of common foods, like: 

If you’re found to have low B12, your healthcare provider may first try over-the-counter supplementation like a dissolvable B12 capsule or tablet or a B12 nasal spray. But if they don’t get your B12 level where it needs to be, injections may be the next step.

“As people age, they sometimes have trouble absorbing vitamin B12, even when taking pills by mouth,” Dr. Goodman explains. “That’s when we think about vitamin B12 via injection.”


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