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Neo-Cytamen Side Effects

Generic Name: hydroxocobalamin

Note: This page contains side effects data for the generic drug hydroxocobalamin. It is possible that some of the dosage forms included below may not apply to the brand name Neo-Cytamen.

For the Consumer

Applies to hydroxocobalamin: intravenous powder for solution

As well as its needed effects, hydroxocobalamin (the active ingredient contained in Neo-Cytamen) may cause unwanted side effects that 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

Minor Side Effects

Some hydroxocobalamin side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

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.

It is possible that some side effects of Neo-Cytamen may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

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.