You should not use this medication 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.
To treat pernicious anemia, you will have to use this medication on a regular basis for the rest of your life. Not using the medication can lead to irreversible nerve damage in your spinal cord.
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.
Your dose needs may change if you become pregnant, if you breast-feed, or if you eat a vegetarian diet. Tell your doctor about any changes in your diet or medical condition.