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Neo-Cytamen Side Effects

Generic Name: hydroxocobalamin

Note: This document contains side effect information about hydroxocobalamin. Some of the dosage forms listed on this page may not apply to the brand name Neo-Cytamen.

For the Consumer

Applies to hydroxocobalamin: intravenous powder for solution

Along with its needed effects, hydroxocobalamin (the active ingredient contained in Neo-Cytamen) 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 hydroxocobalamin:

More Common

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 side effects of hydroxocobalamin 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:

More Common

  • Blemishes on the skin
  • dry, red, hot, or irritated skin
  • nausea
  • pimples
  • red colored urine

Incidence Not Known

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.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

More about Neo-Cytamen (hydroxocobalamin)

Consumer resources

Other brands: Cyanokit

Professional resources

Related treatment guides