Applies to cyanocobalamin: intramuscular solution. Other dosage forms:

• nasal spray

Serious side effects of Cyanocobalamin

Along with its needed effects, cyanocobalamin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking cyanocobalamin:

Incidence not known

• Abdominal or stomach pain
• bleeding from the gums or nose
• blue lips and fingernails
• chest pain
• cough
• coughing that sometimes produces a pink frothy sputum
• decreased urine output
• difficult, fast, noisy breathing, sometimes with wheezing
• difficulty with swallowing
• dilated neck veins
• dizziness
• extreme fatigue
• eye pain
• fast heartbeat
• headache
• hives, itching, or skin rash
• increased sweating
• irregular breathing
• irregular heartbeat
• pale skin
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• ringing in the ears
• swelling of the face, fingers, feet, or lower legs
• tightness in the chest
• unusual tiredness or weakness
• weight gain

Other side effects of Cyanocobalamin

Some side effects of cyanocobalamin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

• Diarrhea
• skin rash with a general disease

For Healthcare Professionals

Applies to cyanocobalamin: compounding powder, injectable solution, intramuscular solution, nasal gel, nasal spray, oral liquid, oral tablet, oral tablet chewable, oral tablet disintegrating, oral tablet extended release, sublingual liquid, sublingual lozenge, sublingual tablet.

Cardiovascular

Frequency not reported: Congestive heart failure, peripheral vascular thrombosis, cardiac arrest, low blood pressure^[Ref]

Hypersensitivity

Patients sensitized to the injectable product are often able to tolerate the oral route without problems.^[Ref]

Frequency not reported: Anaphylactic shock and death, allergic hypersensitivity reactions^[Ref]

Gastrointestinal

Frequency not reported: Mild transient diarrhea, prolonged abdominal pain, prolonged nausea or vomiting^[Ref]

Nervous system

Frequency not reported: Severe dizziness, drowsiness, muscular paralysis, loss of consciousness^[Ref]

Dermatologic

Frequency not reported: Itching, transitory exanthema, acneiform eruptions, bullous eruptions^[Ref]

Respiratory

Frequency not reported: Pulmonary edema^[Ref]

Metabolic

Frequency not reported: Hypokalemia^[Ref]

Oncologic

Frequency not reported: Polycythemia vera^[Ref]

Ocular

Frequency not reported: Vision problems^[Ref]

Other

Frequency not reported: Feeling of swelling of entire body^[Ref]