Vitamin B12 Overdose

Vitamin B12 is a water-soluble vitamin essential for forming red blood cells, DNA synthesis, and nerve function. However, too much vitamin B12 can be toxic to your body. Here’s how much you should take and what signs to look out for if you’re taking too much.

You’re probably aware of the many vitamin B12 advantages that come with consuming enough of the mineral. In reality, sufficient amounts are required to sustain hormone balance, nerve cell health, DNA synthesis, and enzyme creation, to mention a few. What happens if you consume too much vitamin B12, on the other hand? Is it possible to overdose on vitamin B12?

Although vitamin B12 overdose is uncommon, research indicates that specific individuals are more susceptible to adverse consequences from consuming too much of the mineral. Are you in danger of taking too much vitamin B12? Supplementing with this vital vitamin should be done with caution if you have specific health problems.

What Is the Right Vitamin B12 Dose?

Your age, lifestyle changes, food, and health problems affect the quantity of vitamin B12 you require to prevent a deficit. Vitamin B12 should be taken in the following amounts per day, according to the National Institutes of Health:

  • 0.4 micrograms from birth to 6 months.
  • 0.5 micrograms for infants aged 7–12 months.
  • 0.9 micrograms for children aged 1 to 3 years.
  • 1.2 micrograms for children aged 4–8 years.
  • 1.8 micrograms for children aged 9 to 13.
  • Teenagers between the ages of 14 and 18: 2.4 micrograms.
  • Adult males and females 2.4 micrograms for those aged 18 to 50.
  • Adult males and females over the age of 50: 25–250 micrograms.
  • 2.6 micrograms for pregnant women.
  • 2.8 micrograms for nursing mothers.

Adults over 50 are at a higher risk of vitamin B12 insufficiency because they generate less stomach acid, which is required for efficient conversion of the vitamin. For older people, studies indicate that consuming 125–250 mcg of vitamin B12 helps maintain normal B12 levels. It’s a good idea to talk to your doctor about the optimal dose for your particular requirements.

A few other groups need additional vitamin B12, typically in the form of a supplement, to prevent deficiency. For example, people who eat a vegan or vegetarian diet should take one oral dosage of 50–100 mcg per day.

People with gastrointestinal problems or pernicious anemia should take a daily dosage of one milligram of B12, either by injection or by mouth. If you have a disease that prevents you from adequately converting or absorbing vitamin B12, talk to your doctor about the optimum dosage for you.

Symptoms and Consequences

What happens if we consume too much vitamin B12, even though it is an essential vitamin that we need for healthy development and function? There is no acceptable upper consumption limit because vitamin B12 is considered a vitamin with minimal toxicity levels. In addition, there is no known maximum daily dosage that causes harmful effects in the general public.

However, some individuals may be more susceptible to vitamin B12 overload than others. This includes individuals who have renal or liver illness, blood disorders, and pregnant women. According to research, overeating vitamin B12 may cause:

  • Increased risk of cardiovascular events in diabetic nephropathy patients: A research published in JAMA aimed to see whether B vitamin treatment might delay the development of diabetic nephropathy (kidney damage caused by diabetes) and avoid vascular problems in diabetic nephropathy patients. For 36 months, patients were given either a single B vitamin pill containing 2.5 milligrams of folic acid, 25 milligrams of vitamin B6 and one milligram of vitamin B12 each day or a placebo. Researchers discovered that those in the therapy group had worse kidney function and had more vascular events, such as heart attacks and strokes.
  • Hurt unborn children: According to research published in Pediatric Perinatal Epidemiology, very high plasma folate and vitamin B12 levels in pregnant women were linked to an increased risk of autistic spectrum disorder. The findings of this study do not cast doubt on the necessity of obtaining enough of these vitamins during pregnancy. Still, according to the researchers, they raise worries about the effects of a vitamin B12 excess on children.

Vitamin B12 injections are sometimes linked with severe side effects. The following are some of the most frequent complaints:

  • Headache
  • Swelling
  • Rash
  • Flushing of the face
  • Itchy skin
  • Dizziness
  • Numbness
  • Diarrhea
  • Vomiting
  • Blood pressure that is too high
  • Symptoms of the cold
  • Anxiety

Causes of Overdose

Vitamin B12 is a water-soluble vitamin, which means that if we consume too much of it, the excess is excreted via the urine. Therefore, it is virtually difficult to overdose on the vitamin as a result of this. Furthermore, we know that only a tiny portion of vitamin B12 consumed orally is absorbed.

So, what are the signs and symptoms of a vitamin B12 overdose? According to research, mega doses of two milligrams per day are safe for treating a vitamin B12 deficiency. However, mega doses of B12 should not be taken by those who do not have a weakness.

Additionally, some individuals have difficulty adequately absorbing the vitamin due to GI tract problems or a lack of stomach acid. Taking more and more vitamin B12 isn’t going to fix their issue for these individuals. In these instances, a health care practitioner must treat the cause of malabsorption.


According to the Institute of Medicine, excessive vitamin B12 consumption through food and supplements has no negative consequences in healthy people. However, high dosages of vitamin B12 will not enhance your quality of life if you don’t have a vitamin B12 deficit, to begin with, or if you don’t treat the underlying reasons for a deficiency first.

Vitamin B12 insufficiency, according to Cornell University researchers, must be appropriately identified and treated. However, to avoid recurrence and additional problems, the underlying source of the deficit must also be treated. This includes information on how much vitamin B12 you require based on your age, dietary habits, and overall health.

The best approach to avoid a vitamin B12 overload in healthy people is to consume a well-balanced and nutritious diet that includes foods rich in B12, such as organic animal meat, wild seafood, organic dairy products, and eggs.

To prevent deficiency, those over 50, vegetarians and vegans, and individuals with gastrointestinal problems may need to take vitamin B12 supplements. Consult your health care provider before using megadoses of vitamin B12 to treat a deficiency. If you’re having issues with B12 injections, talk to your doctor about switching to oral B12 instead.

Side Effects and Risks

  • Vitamin B12 is a water-soluble nutrient. It is flushed out of the body via urine when eaten in large quantities. As a result, an overdose of vitamin B12 is uncommon. Research indicates that consuming up to 2,000 micrograms per day is safe for low in vitamins.
  • People with specific medical problems or those getting B12 injections, on the other hand, may suffer unpleasant side effects or signs of an overdose.
  • If you’re taking high amounts of vitamin B12 and experiencing adverse side effects, speak to your doctor about it and inquire about having your capacity to absorb the mineral tested.

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.


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