You should not use  cyanocobalamin 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 cobalt or if you have Leber's disease. Cyanocobalamin can lead to optic nerve damage (and possibly blindness) in people with Leber's disease.
Ask a doctor or pharmacist if this medicine is safe to use if you have ever had:
low levels of calcium or potassium in your blood;
heart disease;
a stroke;
a bleeding or blood clotting disorder such as hemophilia;
diabetes;
an iron or folic acid deficiency;
kidney disease; or
any condition that makes it hard for your body to absorb nutrients from food (malabsorption).
Ask a doctor before using this medicine if you are pregnant or breastfeeding.
Do not give this medicine to a child without medical advice.
How should I take oral cyanocobalamin?
Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.
Carefully follow instructions about whether to take your cyanocobalamin with or without food.
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.
Swallow the extended-release tablet whole and do not crush, chew, or break it. Take with a full glass of water.
Do not swallow a lozenge or sublingual tablet whole. Allow it to dissolve in your mouth without chewing. Cyanocobalamin sublingual tablet or liquid should be placed under your tongue.
Pernicious anemia is also treated with folic acid to help maintain red blood cells. However, folic acid will not treat Vitamin B12 deficiency and will not prevent possible damage to the spinal cord. Take all of your medications as directed.
To treat pernicious anemia, you will have to use cyanocobalamin on a regular basis for the rest of your life. Not using the medication can lead to irreversible nerve damage in your spinal cord.
You may need frequent medical tests to help your doctor determine how long to treat you with cyanocobalamin. Using certain other medicines while taking cyanocobalamin may affect the results of these tests.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
