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Niferex-150 Side Effects

Generic Name: ascorbic acid / iron polysaccharide

Note: This page contains side effects data for the generic drug ascorbic acid / iron polysaccharide. It is possible that some of the dosage forms included below may not apply to the brand name Niferex-150.

For the Consumer

Applies to ascorbic acid / iron polysaccharide: oral capsule

Get emergency medical help if you have any of these signs of an allergic reaction while taking ascorbic acid / iron polysaccharide: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using this medication and call your doctor at once if you have a serious side effect such as:

  • fever;

  • severe lower back pain;

  • painful or difficult urination;

  • blood in your urine; or

  • black or dark stools.

Less serious side effects of ascorbic acid / iron polysaccharide may include:

  • stomach upset;

  • nausea or vomiting;

  • diarrhea;

  • constipation; or

  • temporary staining of the teeth.

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 ascorbic acid / iron polysaccharide: oral capsule


Gastrointestinal side effects of ascorbic acid have included nausea, diarrhea, abdominal cramps, and esophagitis. Gastrointestinal side effects of iron polysaccharide have been reported the most frequently. They have included nausea, vomiting, diarrhea, constipation, abdominal pain, flatulence, and heartburn.[Ref]

Nausea, diarrhea, and abdominal cramps have been reported to be associated with ascorbic acid doses exceeding 2 g per day, although there have been some reports with as little as 1 g per day.

Esophagitis has been reported to be associated with prolonged or increased contact of ascorbic acid tablets with the esophageal mucosa.

Constipation from iron may be relieved by administering docusate sodium 100 mg to 200 mg per day in addition to increasing the intake of oral fluids, such as water.[Ref]


Renal side effects of ascorbic acid have included oxalate and urate kidney stones.[Ref]

Hyperoxaluria with ascorbic acid is reported to be dose-related.[Ref]

Nervous system

Nervous system side effects of ascorbic acid have included dizziness, faintness, fatigue, and headache in less than 1% of patients. Migraine headache has also been reported with ascorbic acid.[Ref]

Migraine headache has been reported with a daily dose of 6 grams of ascorbic acid.[Ref]


Conditional scurvy is reported to occur following excessive doses of ascorbic acid over a prolonged period of time. The mechanism of action for this condition is thought to be that large doses of ascorbic acid condition the patient over time for rapid clearance of ascorbic acid resulting in scurvy. The plasma levels of ascorbic acid appear to remain within normal limits. The actual existence of conditional scurvy remains controversial.

Iron overload (i.e., hemosiderosis) has been reported in patients genetically predisposed, or have underlying disorders, that augment the absorption of iron. It has also occurred following administration of excessive parenteral iron therapy, combination of oral and parenteral iron, or in patients with hemoglobinopathies that were erroneously diagnosed as iron deficiency anemia. Hemosiderosis is treated with repeated phlebotomy or long-term administration of deferoxamine. The liver is particularly susceptible to toxicity in iron-overload states.[Ref]

Other side effects from ascorbic acid have included flank pain in less than 1% of patients. Conditional scurvy has also been reported. Other side effects of iron polysaccharide have included iron overload (hemosiderosis). Secondary hemochromatosis due to prolonged iron ingestion has been reported rarely.[Ref]


The majority of hemolysis reports have been associated with patients receiving ascorbic acid who had concurrent glucose-6-phosphate dehydrogenase deficiency.[Ref]

Hematologic side effects of ascorbic acid have included hemolysis.[Ref]


1. Hathcock JN "Vitamins and minerals: Efficacy and safety." Am J Clin Nutr 66 (1997): 427-37

2. "How much vitamin C do you need?" JAMA 281 (1999): 1460

3. Wingard RL, Parker RA, Ismail N, Hakim RM "Efficacy of oral iron therapy in patients receiving recombinant human erythropoietin." Am J Kidney Dis 25 (1995): 433-9

4. KleinSchwartz W "Toxicity of polysaccharid-iron complex exposures reported to poison control centers." Ann Pharmacother 34 (2000): 165-9

5. Glassman E "Oral iron therapy with ferrous fumarate and polysaccharide iron complex." ANNA J 19 (1992): 277-8,323

6. Levine M, Dhariwal KR, Welch RW, Wang Y, Park JB "Determination of optimal vitamin C requirements in humans." Am J Clin Nutr 62(6 Suppl) (1995): s1347-56

7. "Multum Information Services, Inc. Expert Review Panel"

It is possible that some side effects of Niferex-150 may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

More about Niferex-150 (ascorbic acid / iron polysaccharide)

Consumer resources

Other brands: Ferrex 150 Plus, Fe-Tinic 150

Other Formulations

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