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Vitamin B12 (cyanocobalamin, dietary supplement)

Written by Stephanie Nera, RPh, PharmD · Pharmacology

Updated Jul 07, 2021

Vitamin B12, also known as cyanocobalamin, is one of many types of B vitamins that the body needs to function. Vitamin B12 is important in the synthesis of new red blood cells, nerve cell health, and releasing energy from food. It also works alongside folic acid.

Vitamin B12 is not made in the human body, so it must be ingested either through food or dietary supplements. A deficiency of B12 may result in different types of anemia.

vitamin B12


What is vitamin B12 used for?

  • Prevent vitamin B12-deficiency anemia
  • Boost energy
  • Supplement vegetarian and vegan diets

How should I take vitamin B12?

Vitamin B12 is available as an oral tablet and injectable solution. Many multivitamins contain several types of B vitamins as well as other vitamins and minerals. The oral tablet should be taken by mouth without chewing or crushing it. It is best to take it before a meal.

For parenteral dosage forms, only a licensed healthcare professional should administer it.

How do I store vitamin B12?

Store this product at room temperature away from direct light and moisture. To prevent drug damage, you should not store it in the bathroom or the freezer. 

There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & Warnings

What should I know before using vitamin B12?

Vitamins, including vitamin B12, are generally safe to take at any time. As a water-soluble vitamin, an overdose is less likely, however, it can still occur at extremely high, frequent doses.

Most people receive enough vitamins and minerals by eating balanced meals. Only take vitamin and food supplements if you are directed to do so by your doctor.

Before using this drug, tell your doctor if you are/have:

  • Pregnant or breastfeeding.
  • Taking any other medicines. This includes any prescription, OTC, and herbal remedies.
  • An allergy to any of the ingredients of this product.
  • Any other illnesses, disorders, or medical conditions.

Is it safe during pregnancy or breastfeeding?

Vitamin B12 may be recommended for pre- and post-natal supplementation. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as determined by your doctor.

Vitamin B12 passes into breast milk and adds to the nutritional content of breast milk. Increased intake of vitamins may be needed to adequately cover both the mother and baby’s needs.

Side Effects

What side effects can occur from vitamin B12?

Like all drugs, this product may have side effects. If they occur, side effects are generally mild and resolve once treatment is finished or the dose is lowered. Some reported side effects include:

  • Upset stomach
  • Headache
  • Unusual or unpleasant taste in your mouth
  • Infection
  • Asthenia
  • Hypersensitivity

However, not everyone experiences these side effects. In addition, some people may experience other side effects. So, if you have any concerns about a side effect, please consult your doctor or pharmacist.


What drugs may interact with vitamin B12?

This medication may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. 

To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. 

Drugs with known interactions:

  • Chloramphenicol
  • Colchicine

If you experience an adverse drug interaction, inform your doctor immediately to reevaluate your treatment plan. Approaches include dose adjustment, drug substitution, or ending therapy.

Does food or alcohol interact with vitamin B12?

This drug may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Limit your alcohol consumption as it can decrease the amount of B12 in the body. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with vitamin B12?

This drug may interact with underlying conditions. This interaction may worsen your health condition or alter the way the drug works. Therefore, it is important to always let your doctor and pharmacist know all the health conditions you currently have.


The information provided is not a substitute for any medical advice. Therefore, you should always consult with your doctor or pharmacist before using any medication.

What is the dose for an adult?

Pernicious or macrocytic anemia

  • Take 2000 mcg (2 mg) per day.

Megaloblastic anemia caused by vitamin B12 deficiency

  • Take 50 to 150 mcg per day.

What is the dose for a child?

Pernicious or macrocytic anemia

  • Take 1000 mcg (1 mg) per day or every 2 weeks.

How is vitamin B12 available?

This drug is available in the following brands, dosage forms, and strengths:

  • GNC Cyanocobalamin 1000 mcg (1 mg)
  • Neramin-12 OD tablet 1 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.

What should I do if I miss a dose?

If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Written by

Stephanie Nera, RPh, PharmD


Updated Jul 07, 2021

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