Generic name: cyanocobalamin (injection) [ sye-AN-oh-koe-BAL-a-min ]
Brand names: Vitamin B12, Vitamin B-12
Drug class: Vitamins
What is Vitamin B-12 ?
Vitamin B-12 is used to treat vitamin B12 deficiency in people with pernicious anemia and other conditions.
Vitamin B-12 may also be used for purposes not listed in this medication guide.
You should not use Vitamin B-12 if you are allergic to cobalt, or if you have Leber’s disease.
Before taking this medicine
You should not use this medicine if you are allergic to Vitamin B-12 or cobalt, or if you have Leber’s disease (an inherited form of vision loss). This medicine can lead to optic nerve damage (and possibly blindness) in people with Leber’s disease.
Tell your doctor if you have ever had:
- eye problems or Leber’s disease (in you or a family member);
- kidney or liver disease ;
- iron or folic acid deficiency;
- any type of infection; or
- if you are receiving any medication or treatment that affects bone marrow.
Tell your doctor if you are pregnant or breastfeeding. Your dose needs may be different during pregnancy or while you are nursing.
How is Vitamin B-12 given?
Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.
Vitamin B-12 is injected into a muscle or under the skin. A healthcare provider may teach you how to properly use the medication by yourself.
Your dose needs may change if you become pregnant, if you breastfeed, or if you eat a vegetarian diet. Tell your doctor about any changes in your diet or medical condition.
Always follow directions on the medicine label about giving Vitamin B-12 to a child. Your child’s dose will depend on age, weight, diet, and other factors.
For pernicious anemia, you may have to use Vitamin B-12 for the rest of your life. Do not stop using the medicine unless your doctor tells you to. Untreated vitamin B12 deficiency can lead to anemia or irreversible nerve damage.
Pernicious anemia is also treated with folic acid to help maintain red blood cells. Folic acid alone will not treat Vitamin B12 deficiency or prevent possible damage to the spinal cord. Use all medications as directed.
You will need frequent medical tests.
Vitamin B-12 can affect the results of certain medical tests. Tell any doctor who treats you that you are using Vitamin B-12.
Store this medication at room temperature away from moisture, heat, and light.
Use a needle and syringe only once and then place them in a puncture-proof “sharps” container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.
Detailed Vitamin B12 dosage information
What happens if I miss a dose?
Call your doctor for instructions if you miss a dose.
Get your prescription refilled before you run out of medicine completely.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid while using Vitamin B-12?
Avoid drinking large amounts of alcohol while you are being treated with Vitamin B-12.
Vitamin B-12 side effects
Get emergency medical help if you have signs of an allergic reaction: hives ; difficulty breathing; swelling of your face, lips, tongue, or throat.
Vitamin B-12 may cause serious side effects. Call your doctor at once if you have:
- heart problems–swelling, rapid weight gain, feeling short of breath;
- fluid build-up in or around the lungs–pain when you breathe, feeling short of breath while lying down, wheezing, gasping for breath, cough with foamy mucus, cold and clammy skin, anxiety , rapid heartbeats; or
- low potassium level–leg cramps, constipation , irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling.
Common side effects of Vitamin B-12 may include:
- diarrhea ; or
- swelling anywhere in your body.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Vitamin B12 side effects (more detail)
What other drugs will affect Vitamin B-12?
Other drugs may affect Vitamin B-12, including prescription and over-the-counter medicines, vitamins , and herbal products . Tell your doctor about all your current medicines and any medicine you start or stop using.