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Multivitamin with iron Side Effects

Not all side effects for multivitamin with iron 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 multivitamin with iron: oral capsule, oral capsule extended release, oral liquid, oral powder for reconstitution, oral tablet, oral tablet chewable, oral tablet extended release

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

When taken as directed, multivitamins are not expected to cause serious side effects.

Call your doctor if you have:

  • bright red blood in your stools; or

  • pain in your chest or throat when swallowing a tablet.

Common side effects may include:

  • constipation, diarrhea;

  • nausea, vomiting, heartburn;

  • stomach pain, upset stomach;

  • black or dark-colored stools or urine;

  • temporary staining of the teeth;

  • headache; or

  • unusual or unpleasant taste in your mouth.

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 multivitamin with iron: injectable solution, oral capsule, oral capsule extended release, oral liquid, oral powder for reconstitution, oral tablet, oral tablet chewable, oral tablet extended release


Gastrointestinal side effects associated with oral iron therapy have included nausea, constipation, anorexia, heartburn, vomiting, and diarrhea. These effects are generally dose-related. In addition, stools may appear darker in color in patients taking products containing iron. Iron oral preparations may rarely cause Hemoccult-positive stools, patients with positive tests generally require further work-up.[Ref]


Stained teeth have primarily occurred following ingestion of iron liquid preparation.

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 associated with oral iron products have included stained teeth and iron overload (hemosiderosis). Secondary hemochromatosis due to prolonged iron ingestion has been reported rarely.[Ref]


Metabolic side effects associated with iron have included decreased absorption of thyroxine (T4).[Ref]


1. Hutchins L, Lipschitz D "Iron and folate metabolism in renal failure." Semin Nephrol 5 (1985): 142-6

2. Brock C, Curry H, Hanna C, Knipfer M, Taylor L "Adverse effects of iron supplementation: a comparative trial of a wax- matrix iron preparation and conventional ferrous sulfate tablets." Clin Ther 7 (1985): 568-73

3. Pollycove M "Iron overload syndromes." Clin Physiol Biochem 4 (1986): 61-77

4. M'Seffar A, Fornasier VL, Fox IH "Arthropathy as the major clinical indicator of occult iron storage disease." JAMA 238 (1977): 1825-8

5. Falk RJ, Mattern WD, Lamanna RW, Gitelman HJ, Parker NC, Cross RE, Rastall JR "Iron removal during continuous ambulatory peritoneal dialysis using deferoxamine." Kidney Int 24 (1983): 110-2

6. Bacon BR "Causes of iron overload." N Engl J Med 326 (1992): 126-7

7. Surks MI, Sievert R "Drugs and thyroid function." N Engl J Med 333 (1995): 1688-94

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