Cyanocobalamin Side Effects
Some side effects of cyanocobalamin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to cyanocobalamin: oral tablet, oral tablet extended release, sublingual tablet
Get emergency medical help if you have any of these signs of an allergic reaction while taking cyanocobalamin: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have a serious side effect such as:
feeling short of breath, even with mild exertion;
swelling, rapid weight gain; or
unusual warmth, redness, or pain in an arm or leg.
Less serious side effects of cyanocobalamin may include:
headache, dizziness, weakness;
nausea, upset stomach, diarrhea;
numbness or tingling;
itching or rash.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to cyanocobalamin: compounding powder, injectable solution, intramuscular solution, nasal gel, nasal spray, oral tablet, oral tablet extended release, sublingual tablet
Cardiovascular side effects associated with parenteral cyanocobalamin have included congestive heart failure, pulmonary edema, and peripheral vascular thrombosis. These effects were usually reported early in treatment.
Dermatologic side effects associated with both intranasal and parenteral cyanocobalamin have included itching and transitory exanthema.
Dermatologic side effects have rarely included exacerbation or onset of inflammatory acne and folliculitis related to B12.
Exacerbation or onset of inflammatory acne and folliculitis have been seen with high doses of B12 (5 to 10 mg/week). The etiology and pathogenic mechanisms of vitamin B12-induced acne are unknown. When present, acneiform eruptions usually occur on the facial area after the first or second injection, and typically disappear within 8 to 10 days after stopping therapy.
A single case of a severe skin eruption resembling acne rosacea that was temporally associated with daily ingestion of 100 mcg of B12 (with 100 mg of B6) has been reported. The rash resolved upon discontinuation of both drugs and recurred upon rechallenge with half the doses.
Some have suspected sorbitol or iodine that is present in some ampules of B12 may be the cause of at least some cases of skin eruptions associated with this drug.
A single case of cecal vitamin B12 bezoar has been reported in an elderly man with a history of multiple gastrointestinal surgeries.
Gastrointestinal side effects associated with parenteral cyanocobalamin have included dyspepsia, nausea, vomiting, and mild transient diarrhea.
Gastrointestinal side effects associated with intranasal cyanocobalamin have included glossitis and nausea.
Anaphylactic reactions have been reported primarily with parenteral administration of B12 and are thought to be the result of impurities of B12 preparations that are no longer manufactured. They may occur soon after a sensitizing dose, within a few weeks or months, or rarely after a latency of several years.
Hypersensitivity side effects associated with parenteral cyanocobalamin have rarely included anaphylactic reactions and death.
Nervous system side effects associated with parenteral cyanocobalamin have included abnormal gait, asthenia, anxiety, dizziness, hypoesthesia, incoordination, nervousness, and incoordination.
Nervous system side effects associated with both parenteral and intranasal cyanocobalamin have included paresthesia and headache.
Hematologic side effects have included polycythemia vera.
Musculoskeletal side effects associated with parenteral cyanocobalamin have included arthritis, back pain, and myalgia.
Respiratory side effects associated with parenteral cyanocobalamin have included dyspnea.
Respiratory side effects associated with both parenteral and intranasal cyanocobalamin have included rhinitis.
Immunologic side effects associated with both parenteral and intranasal cyanocobalamin have included infection.
Other side effects associated with parenteral administration of cyanocobalamin have included feeling of swelling of entire body, back pain, and generalized pain.
More cyanocobalamin resources
- Cyanocobalamin Prescribing Information (FDA)
- Calomist Consumer Overview
- Calomist Prescribing Information (FDA)
- Nascobal Monograph (AHFS DI)
- Nascobal Prescribing Information (FDA)
- Nascobal spray MedFacts Consumer Leaflet (Wolters Kluwer)
- Vitamin b12
- vitamin b12 Nasal, Oral, Parenteral Advanced Consumer (Micromedex) - Includes Dosage Information
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