Before taking cyanocobalamin, tell your doctor or pharmacist if you are allergic to it; or to any form of vitamin B12; or to cobalt; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

If you have any of the following health problems, consult your doctor or pharmacist before using this medication: a certain eye disease (Leber's optic neuropathy), a certain blood disorder (polycythemia vera), gout, iron or folic acid deficiency anemia, low potassium blood levels (hypokalemia).

Cyanocobalamin taken by mouth should only be used if your body can properly absorb it. You may need a form of vitamin B12 that is injected or inhaled in the nose if you have any of the following health problems: pernicious anemia, food absorption problems, stomach/intestinal surgery (such as gastric bypass or bowel resection), stomach/intestinal disease (such as Crohn's disease, colitis, diverticulitis, pancreatic insufficiency), irradiation of the small bowel.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Cyanocobalamin is safe to use during pregnancy when taken in recommended doses. Higher doses should be used only when clearly needed. Discuss the risks and benefits with your doctor.

Cyanocobalamin passes into breast milk and is unlikely to harm a nursing infant when used in recommended doses. Consult your doctor before breastfeeding.