Can You Take Too Much Vitamin B12 And What Are The Side Effects?

B12 Energy Boost Cocktail

Increase your energy levels and get a rejuvenating mix of vitamins that includes:

• B12
• B Complex
• Vitamin C

Vitamin B12 (also known as cobalamin) is a water-soluble nutrient that forms red blood cells, produces DNA and energy, and helps to regulate cell metabolism and the functioning of your body’s nerves.

This article will discuss whether it’s possible to overdose on vitamin B12, the levels at which someone might overdose, and what can happen if so.

What is Vitamin B12 and Why is it Important?

Vitamin B12 (also known as cobalamin) is essential for nerve health, DNA creation, red blood cell formation and helps regulate cell metabolism and the functioning of your body’s nerves.

Vitamin B12 is water-soluble and excess amounts are naturally excreted, therefore supplementation should be discussed with a doctor to avoid adverse side effects. Vitamin B12 supplements are available in oral form to maintain normal levels. Intravenous (IV) infusions, injections, and nasal sprays are options used to treat a vitamin B12 deficiency.

However, most people can meet the recommended daily intake through normal foods in their diet such as:

• Meat
• Poultry
• Eggs
• Fish
• Fortified Cereals
• Dairy Products

Is it Possible to Overdose on Vitamin B12?

Vitamin B12 is a water-soluble vitamin, so it’s generally considered safe even at high doses. There is currently no Tolerable Upper Intake Level (UL) for B12 because there isn’t enough scientific evidence to establish one. Any excess B12 that your body doesn’t use gets flushed out in your urine.

However, if you supplement with excessive amounts of vitamin B12 (also called megadosing), you may experience some negative side effects. Some studies suggest that megadoses, especially from vitamin B12 injections, can cause acne and rosacea, which is a skin condition that forms red patches on your face.

The recommended daily intake (RDI) of vitamin B12 is 2.4 micrograms (mcg) for both men and women. Pregnant women need 2.6 mcg per day, and breastfeeding women should take 2.8 mcg every day. For those with a vitamin B12 deficiency, a dose of 1,000 mcg via the intramuscular route is recommended once a month. Newly diagnosed patients should receive 1,000 mcg intramuscularly once a week for four weeks to replenish stores before switching to once-monthly dosing.

While doses up to 2,000 mcg can be used safely to treat vitamin B12 deficiency, you should not take such high doses if you do not have a deficiency and if your doctor hasn’t recommended it.

Regarding absorption, your body only absorbs about 10 mcg of a 500-mcg dose if you do not have a vitamin B12 deficiency. This is because the absorption of B12 is dependent on intrinsic factor, a protein made in your stomach. Conditions like pernicious anemia, atrophic gastritis, and certain gastrointestinal surgeries can affect the production of intrinsic factor, thereby impairing B12 absorption.

While high doses of vitamin B12 are generally safe for most people, it’s important to follow recommended guidelines and consult with your doctor before starting any new supplement regimen.

How Much Vitamin B12 Does it Take to Overdose?

As stated previously, vitamin B12 overdose is unlikely because it is water-soluble, and your body flushes out any excess through urine. There is no upper limit for B12 since there isn’t enough scientific evidence to establish one. While doses up to 2,000 mcg can be safely used to treat B12 deficiency, you should not take such high doses without a deficiency or your doctor’s recommendation.

Absorption of B12 depends on intrinsic factor, a stomach protein, and certain conditions can affect this process. Signs of too much B12 include acne and rosacea, indicating elevated B12 levels.

What Can Happen if I Have too Much Vitamin B12?

While vitamin B12 is generally safe, excessive amounts can lead to some side effects. Side effects can depend on how the vitamin B12 is administered (for example, orally or via injection).

What are The Side Effects of Vitamin B12?

• Frequent Headaches 
• Diarrhea
• Nausea
• Vomiting
• Tiredness
• Feeling Weak
• Tingling sensation in hands and feet
• Increased Risk of Bone Fractures

Vitamin B12 Injection Side Effects

Often used to treat severe deficiencies, vitamin B12 injections come with additional potential side effects, which include:

• Itching (at injection site)
• Skin rashes (at injection site)
• Dizziness
• Swelling

Severe Vitamin B12 Injection Side Effects

More serious side effects from vitamin B12 injections can include:

• Pulmonary Embolism
• Congestive Heart Failure
• Vein Thrombosis/Blood Clots
• Anaphylaxis, an allergic reaction (rare)
  
  Anaphylaxis is life-threatening and causes swelling of the face, tongue, and throat, making it difficult to breathe and swallow. Immediate medical attention is necessary if this occurs.

Medication Interactions

While vitamin B12 supplements are generally considered safe at appropriate doses, interactions with certain medications can affect B12 absorption. These include:

• Aminosalicylic Acid
• Colchicine
• Metformin
• Proton Pump Inhibitors 
• Vitamin C supplements 

What is the Correct Dosage of Vitamin B12? 

The Recommended Daily Allowance (RDA) for Vitamin B12 varies by age, sex, and individual health factors. Below are the general guidelines:

Infants:

• 0-6 months: 0.4 mcg
• 7-12 months: 0.5 mcg

Children:

• 1-3 years: 0.9 mcg
• 4-8 years: 1.2 mcg
• 9-13 years: 1.8 mcg

Adolescents & Adults:

• 14-18 years: 2.4 mcg

Adults (19 years and older): 2.4 mcg

For those with a vitamin B12 deficiency, a dose of 1,000 mcg via the intramuscular route is recommended once a month. Newly diagnosed patients should receive 1,000 mcg intramuscularly once a week for four weeks to replenish stores before switching to once-monthly dosing.

Pregnancy and Vitamin B12

The Recommended Daily Allowance (RDA) for pregnant women is 2.6 mcg. For women who are breastfeeding, the RDA is 2.8 mcg.

When Should I see a Doctor?

Consult a doctor about Vitamin B12 before beginning any vitamin supplementation regimen to determine if a deficiency exists and if there are potential adverse reactions with any current medications you are taking.

Consult your doctor immediately if experiencing any of the severe reactions noted above from IV injections of vitamin B12.

Pregnant and breastfeeding women should consult their OB/GYN about potential vitamin B12 deficiencies and if supplemental action is required.

FAQ

Can Too Much Vitamin B12 be Harmful?

Vitamin B12 is generally considered safe even at high doses. There is currently no Tolerable Upper Intake Level (UL) for B12 because there isn’t enough scientific evidence to establish one. 

With that said, in one case study, a young woman taking high doses of vitamin B12 injections for pernicious anemia developed acne, face redness, insomnia, headache, and palpitations. Her symptoms improved on their own within two weeks of stopping daily vitamin B12 usage. Additionally, a recent study found that high blood concentrations of vitamin B12 appeared to be linked with early death, though researchers are unclear why at this time.

Is it Okay to Take 5000 mcg of B12 a Day?

There is no upper limit for vitamin B12 since there isn’t enough scientific evidence to establish one. However, while doses up to 2,000 mcg or 5,000 mcg can be safely used to treat vitamin B12 deficiency, you should not take such high doses without a deficiency and your doctor’s recommendation.

How to flush out excess B12?

Vitamin B12 is water-soluble and any excess vitamin B12 that your body doesn’t absorb gets flushed out in your urine.

Your body only absorbs about 10 mcg of a 500-mcg dose if you do not have a vitamin B12 deficiency. This is because the absorption of vitamin B12 is dependent on an intrinsic factor, a protein made in your stomach. Conditions like pernicious anemia, atrophic gastritis, and certain gastrointestinal surgeries can affect the production of intrinsic factor, thereby impairing vitamin B12 absorption.

Last Words

Vitamin B12 is a water-soluble member of the B-complex family that is necessary for nerve health, DNA creation, red blood cell formation, metabolic health, and more. This vitamin cannot be made by your body and must be obtained from outside sources such as diet and supplements. Most people can obtain the recommended 2.9mcg of B12 through their daily diet.

Vitamin B12 supplements may offer many potential health benefits, including helping improve mood, supporting bone and eye health, promoting healthy DNA and red blood cell creation, and more. There is currently no established Tolerable Upper Intake Level for Vitamin B12 because it is water-soluble, not stored by the body, and excess amounts are naturally excreted as waste. As such, it is unlikely for most people to experience a B12 overdose from taking too much of this vitamin.

If you want to supplement with Vitamin B12, it’s important to speak with your doctor first. They can advise you if doing so is safe and can help you reach your health goals.

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