The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Your doctor or pharmacist can often prevent or manage interactions by changing how you use your medications or by close monitoring.
To help your doctor and pharmacist give you the best care, be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products) before starting treatment with this product. While using this product, do not start, stop, or change the dosage of any other medicines you are using without your doctor's approval.
Some products that may interact with this drug include: drugs that affect the bone marrow (such as chloramphenicol), vitamins/supplements that contain intrinsic factor.
Certain medications can decrease the absorption of vitamin B12, including: colchicine, metformin, extended-release potassium products, antibiotics (such as gentamicin, neomycin, tobramycin), anti-seizure medications (such as phenobarbital, phenytoin, primidone), medications to treat heartburn (such as H2 blockers including cimetidine/famotidine, proton pump inhibitors such as omeprazole/lansoprazole).
Vitamin B12 is an ingredient found in many combination vitamin and nutritional products. Tell your doctor or pharmacist if you are taking other products that contain cyanocobalamin, vitamin B12, or hydroxocobalamin.
Cyanocobalamin may interfere with certain laboratory tests (including intrinsic factor, blood tests for other types of anemia), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.
Certain drugs may interfere with laboratory tests for vitamin B12 levels, possibly causing false results. Tell laboratory personnel and all your doctors if you take any of the following: antibiotics (such as amoxicillin, erythromycin), methotrexate, pyrimethamine.
This document does not contain all possible drug interactions. Keep a list of all the products you use. Share this list with your doctor and pharmacist to lessen your risk for serious medication problems.