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Tandem Side Effects

Generic Name: ferrous fumarate / iron polysaccharide

Note: This document contains side effect information about ferrous fumarate / iron polysaccharide. Some of the dosage forms listed on this page may not apply to the brand name Tandem.

For the Consumer

Applies to ferrous fumarate / iron polysaccharide: oral capsule

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

Common side effects may include:

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 ferrous fumarate / iron polysaccharide: oral capsule


Cases of gastrointestinal discomfort are typically mild and subside with continuation of therapy. According to the manufacturer, ferrous fumarate-iron polysaccharide is best absorbed when administered at bedtime; however, gastrointestinal side effects may be minimized when administered with a meal.

Constipation 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]

Gastrointestinal side effects have included nausea, constipation, anorexia, heartburn, vomiting and diarrhea. In addition, stools may appear darker in color in patients taking ferrous fumarate.[Ref]


It has been hypothesized that gastroenteritis is caused by bacteria that become virulent in the presence of iron overload resulting in a systemic infection. Treatment consists of discontinuing deferoxamine and initiating appropriate antimicrobial therapy.[Ref]

Immunologic side effects associated with oral iron products have rarely included gastroenteritis associated with Yersinia enterocolitica and Listeria monocytogenes in patients with iron overload status receiving treatment with deferoxamine.[Ref]


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 have included iron overload (hemosiderosis). Secondary hemochromatosis due to prolonged iron ingestion has been reported rarely.[Ref]


1. "Product Information. Tandem (ferrous fumarate-iron polysaccharide)." U.S. Pharmaceutical Corporation, Decatur, GA.

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.