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Hydroxocobalamin Side Effects

Not all side effects for hydroxocobalamin may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to hydroxocobalamin: intravenous powder for solution

In addition to its needed effects, some unwanted effects may be caused by hydroxocobalamin. In the event that any of these side effects do occur, they may require medical attention.

If any of the following side effects occur while taking hydroxocobalamin, check with your doctor or nurse immediately:

More common
  • Blurred vision
  • dizziness
  • headache
  • nervousness
  • pounding in the ears
  • redness of the skin
  • slow or fast heartbeat
Incidence not known
  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • cough
  • difficult or labored breathing
  • difficulty with swallowing
  • feeling of warmth
  • hives or welts, itching, or skin rash
  • large, hive-like swelling on the , eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rapid weight gain
  • redness of the face, neck, arms, and occasionally, upper chest
  • sudden sweating
  • tightness in the chest
  • tingling of the hands or feet
  • unusual tiredness or weakness
  • unusual weight gain or loss

Some of the side effects that can occur with hydroxocobalamin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Blemishes on the skin
  • dry, red, hot, or irritated skin
  • nausea
  • pimples
  • red colored urine
Incidence not known
  • Acid or sour stomach
  • being forgetful
  • belching
  • diarrhea
  • heartburn
  • indigestion
  • redness or swelling of the eyes
  • restlessness
  • stomach discomfort, upset, or pain

For Healthcare Professionals

Applies to hydroxocobalamin: compounding powder, injectable solution, intravenous powder for injection


Gastrointestinal side effects have included mild transient diarrhea and nausea.[Ref]


Other side effects have included itching and feeling of swelling of the entire body.[Ref]


Dermatologic side effects have included transitory exanthema and erythema.[Ref]


Hypersensitivity side effects have rarely included anaphylactic reactions.[Ref]


Local side effects have included infusion site reaction and pain with injection.[Ref]


Renal side effects have included chromaturia.


Cardiovascular side effects, following intravenous administration, have included increased blood pressure.[Ref]


1. "Product Information. Hydro-Cobex (hydroxocobalamin)." Major Pharmaceuticals Inc, Rosemont, IL.

2. "Product Information. Cyanokit (hydroxocobalamin)." Meridian Medical Technologies Inc, Columbia, MD.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.