cyanocobalamin at a glance
Medicine class
Vitamin B12 replacement.
Main role
Prevention or treatment of vitamin B12 deficiency and associated macrocytic anaemia.
Available forms
Oral tablets and intramuscular injection.
Cobalt content
Contains cobalt, which matters for people with a known cobalt allergy.
What is cyanocobalamin used for?
Selected products are licensed for:
Nutritional vitamin B12 deficiency.
Prevention or treatment of macrocytic anaemia caused by vitamin B12 deficiency, including pernicious anaemia.
Deficiency following partial gastrectomy or associated with certain malabsorption states.
Tropical sprue, alone or with folic acid, using the selected tablet product.
Use of the selected injection as part of the Schilling test.
How does cyanocobalamin work?
It replenishes vitamin B12, supporting normal red blood-cell production and nervous-system function. It is carried in blood by transcobalamin proteins and stored mainly in the liver.
cyanocobalamin preparations and strengths
Tablet
Route: Oral
Strengths: 50 micrograms
How to take cyanocobalamin
Use the formulation exactly as directed on its label or by the prescriber.
Swallow prescribed tablets whole with water; do not chew or break them.
Where possible, take the selected tablets between meals.
A healthcare professional gives the injection into a muscle.
cyanocobalamin side effects
Common or expected effects
- Most people taking tablets have no side effects.
- Reported non-serious effects, particularly with injection, include injection-site pain or firmness, nausea, flushing, dizziness, fever, chills, malaise, tremor and acne-like eruptions. Their frequency is not established.
Get urgent medical advice
- Allergic skin reactions such as rash, itching or hives require prompt medical advice.
- Rarely, severe allergic reactions including anaphylaxis can occur.
- Blistering skin eruptions, injection-site tissue damage, reactive thrombocytosis and heart rhythm disturbance associated with low potassium have been reported.
cyanocobalamin in pregnancy
Cyanocobalamin can be used during pregnancy when vitamin B12 replacement is needed. Megaloblastic anaemia in pregnancy should not be treated empirically unless vitamin B12 deficiency has been established, because another deficiency may be responsible.
cyanocobalamin while breastfeeding
Cyanocobalamin is compatible with breastfeeding. It occurs naturally in breast milk, and supplemental cyanocobalamin passing into milk is unlikely to harm the infant. Seek advice if the baby feeds poorly or there are other concerns.
cyanocobalamin interactions
Some medicines affect absorption, response or laboratory testing.
Metformin and other biguanides
May reduce oral absorption; clinical response and vitamin B12 status may need review.
Antacids, H2-receptor antagonists and proton-pump inhibitors
Reduced stomach acidity may decrease absorption from tablets or food.
Chloramphenicol
May reduce the haematological response.
Common questions about cyanocobalamin
Answers are fully visible for fast scanning and source review.
Is cyanocobalamin the same as vitamin B12?
It is a manufactured form of vitamin B12 used to replace low body stores.
Why might tablets be unsuitable for some causes of deficiency?
Absorption depends substantially on intrinsic factor and gastrointestinal function, so it may be unreliable in pernicious anaemia, after gastrectomy or with malabsorption.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.