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Fumasorb Side Effects

Generic Name: ferrous fumarate

Note: This page contains information about the side effects of ferrous fumarate. Some of the dosage forms included on this document may not apply to the brand name Fumasorb.

For the Consumer

Applies to ferrous fumarate: chewable tablets, suspension

Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Constipation; darkened or green stools; diarrhea; nausea; stomach upset.

Seek medical attention right away if any of these SEVERE side effects occur while taking ferrous fumarate (the active ingredient contained in Fumasorb)

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); black, tarry stools; blood or streaks of blood in the stool; fever; vomiting with continuing sharp stomach pain.

For Healthcare Professionals

Applies to ferrous fumarate: compounding powder, oral liquid, oral suspension, oral tablet, oral tablet chewable, oral tablet extended release


Gastrointestinal side effects are generally dose-related and have included nausea, constipation, anorexia, heartburn, vomiting and diarrhea. In addition, stools may appear darker in color in patients taking ferrous fumarate (the active ingredient contained in Fumasorb)

Oral preparations may rarely cause Hemoccult-positive stools, patients with positive tests generally require further work-up.[Ref]

Gastrointestinal discomfort may be minimized by initiating ferrous fumarate therapy at smaller doses and gradually titrating upwards until the desired dose is achieved.

Gastrointestinal discomfort may also be minimized by administering each dose with food. However, concurrent administration of ferrous fumarate with food may decrease the amount of iron absorbed.

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]


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


Local side effects have included gangrene.[Ref]

Localized corrosion has been reported in a pregnant woman taking ferrous sulfate (tablet) that lodged in a Meckel's diverticulum.

There have also been reports of wax-matrix ferrous sulfate tablets (delayed-release) lodging in the bowels of patients with strictures.[Ref]


Stained teeth have primarily occurred following ingestion of ferrous fumarate (the active ingredient contained in Fumasorb) liquid preparation. Liquid dosage forms should be diluted in juice or water and sipped through a straw to aid in prevention of staining.

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 stained teeth and iron overload (hemosiderosis). Secondary hemochromatosis due to prolonged iron ingestion has been reported rarely.[Ref]


1. "Product Information. Chromagen Forte (ferrous fumarate)." Savage Laboratories, Melville, NY.

2. Fakir M, Saison C, Wong T, Matta B, Hardin JM "Septicemia due to Yersinia enterocolitica in a hemodialyzed depleted patient receiving omeprazole and oral iron supplementation." Am J Kidney Dis 19 (1992): 282-4

3. Mazzoleni G, deSa D, Gately J, Riddell RH "Yersinia enterocolitica infection with ileal perforation associated with iron overload and deferoxamine therapy." Dig Dis Sci 36 (1991): 1154-60

4. Boelaert JR, van Landuyt HW, Valcke YJ, Cantinieaux B, Lornoy WF, Vanherweghem JL, Moreillon P, Vandepitte JM "The role of iron overload in Yersinia enterocolitica and Yersinia pseudotuberculosis bacteremia in hemodialysis patients." J Infect Dis 156 (1987): 384-7

5. Abcarian PW, Demas BE "Systemic Yersinia enterocolitica infection associated with iron overload and deferoxamine therapy." AJR Am J Roentgenol 157 (1991): 773-5

6. Laine LA, Bentley E, Chandrasoma P "Effect of oral iron therapy on the upper gastrointestinal tract. A prospective evaluation." Dig Dis Sci 33 (1988): 172-7

7. Leighton PM, MacSween HM "Yersinia hepatic abscesses subsequent to long-term iron therapy." JAMA 257 (1987): 964-5

8. Shaffer JL, Higham C, Turnberg LA "Hazards of slow-release preparations in patients with bowel strictures." Lancet 2 (1980): 487

9. Alaily AB "Gangrene of Meckel's diverticulum in pregnancy due to iron tablet." Br Med J 1 (1974): 103

Not all side effects for Fumasorb may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

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