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Elemental Iron Side Effects

Generic name: carbonyl iron

Medically reviewed by Last updated on Apr 5, 2024.

Note: This document contains side effect information about carbonyl iron. Some dosage forms listed on this page may not apply to the brand name Elemental Iron.

Applies to carbonyl iron: oral tablet chewable. Other dosage forms:


  • Accidental overdose of drugs that have iron in them is a leading cause of deadly poisoning in children younger than 6 years of age. Keep away from children. If this drug is taken by accident, call a doctor or poison control center right away.

Serious side effects of Elemental Iron

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Other side effects of Elemental Iron

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

For Healthcare Professionals

Applies to carbonyl iron: oral suspension, oral tablet, oral tablet chewable.


Gastrointestinal side effects have been reported the most frequently. They have included diarrhea (45%) vs. placebo (3%), cramping (38%) vs. placebo (0%), nausea (30%) vs. placebo (8%), constipation (25%) vs. placebo (14%), heartburn (17%) vs. placebo (6%), and epigastric discomfort (16%) vs. placebo (11%).[Ref]

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]


Other side effects have included iron overload (hemosiderosis) and stained teeth. Secondary hemochromatosis due to prolonged iron ingestion has been reported rarely. An unpleasant taste following carbonyl iron (the active ingredient contained in Elemental Iron) ingestion has been reported in 40% to 70% of patients.[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.

Stained teeth have been reported primarily following ingestion of iron liquid preparations. Liquid dosage forms should be diluted in juice or water and sipped through a straw to aid in prevention of staining.[Ref]

Nervous system

Nervous system side effects have included headache (29%) vs. placebo (25%), and weakness (11%) vs placebo (9%).[Ref]

More about Elemental Iron (carbonyl iron)

Patient resources

Other brands

Iron Chews, Icar, Feosol Natural Release, Wee Care

Related treatment guides


1. Gordeuk VR, Brittenham GM, Hughes M, Keating LJ, Opplt JJ (1987) "High-dose carbonyl iron for iron deficiency anemia: a randomized double-blind trial." Am J Clin Nutr, 46, p. 1029-34

2. Gordeuk VR, Brittenham GM, McLaren CE, Hughes MA, Keating LJ (1986) "Carbonyl iron therapy for iron deficiency anemia." Blood, 67, p. 745-52

3. Devasthali SD, Gordeuk VR, Brittenham GM, Bravo JR, Hughes MA, Keating LJ (1991) "Bioavailability of carbonyl iron: a randomized, double-blind study." Eur J Haematol, 46, p. 272-8

4. Gordeuk VR, Brittenham GM, Hughes MA, Keating LJ (1987) "Carbonyl iron for short-term supplementation in female blood donors." Transfusion, 27, p. 80-5

5. "Product Information. Feosol Caplet (carbonyl iron)." SmithKline Beecham

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.