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Table of Contents > Supplements > Iron
Also Known As:  ferrous sulfate, ferrous fumarate, ferrous succinate, ferrous gluconate, ferrous lactate, ferrous glutamate, ferrous glycine
Dietary Sources
Available Forms
How to Take It
Possible Interactions
Supporting Research


Iron is an essential mineral that contributes to many important physiologic functions in the body. Much of the iron in the body is attached to hemoglobin molecules in red blood cells, thereby delivering oxygen to all of the tissues. Extra iron is stored in the liver, bone marrow, spleen, and muscles.

Significant deficiency in iron leads to anemia. The most common symptoms of anemia are weakness and fatigue. Pregnant women, young women during their reproductive years, and children tend to be at the highest risk of becoming deficient in iron. Anemia may be mild, moderate, or severe and may be caused by significant and/or prolonged blood loss such as that from a bleeding ulcer, menstruation, severe trauma, surgery, or a malignant tumor. It can also be caused by an iron-poor diet, inefficient absorption of dietary iron, pregnancy, and the rapid growth that takes place during infancy, early childhood, and adolescence.

On the other hand, excessive iron in the body can lead to a condition known as hemochromatosis, which can cause diabetes, liver damage, and discoloration of the skin.


Anemia: The most important use of iron supplements is to treat anemia caused by iron deficiency. This treatment is directed and supervised by a health care provider, who may first search for the underlying reason for the low levels of iron.

Exercise Capacity
Low levels of iron can lead to diminished exercise capacity, whether anemia is present or not. Therefore, if your iron stores are low (as measured by your doctor), iron supplements (for example, in a multivitamin or iron supplement) may improve endurance during aerobic activities.

Attention-Deficit Hyperactivity Disorder (ADHD)
Symptoms of iron deficiency (including decreased attention, arousal, and social responsiveness) are similar to symptoms of ADHD. There is little scientific evidence, however, that iron supplementation in those who are deficient improves behavior in children with ADHD. Since iron can be toxic in children who are not deficient, there is little justification for its supplementation as a treatment for ADHD in children with normal levels of this mineral. If iron levels are low, a healthcare provider can determine whether replacement is needed.

Cough associated with ACE inhibitor use

One preliminary study suggested that iron supplementation may soothe and even prevent cough associated with a class of medications known as angiotensin-converting enzyme (ACE) inhibitors (such as enalapril, captopril, and lisinopril). ACE inhibitors are medications commonly used to treat high blood pressure and heart failure, but dry cough is a side effect that leads many people to discontinue their use. Despite this encouraging information, it is premature to conclude that taking iron with ACE inhibitors to reduce dry cough is safe or effective.

Plus, it is important to note that taking ACE inhibitors at the same time as iron may diminish the absorption of this nutrient. Therefore, if used together, the two should be taken at least two hours apart. Also, iron is associated with some risk for heart disease. For this reason, it should not be used by individuals with high blood pressure or heart failure without the consent and supervision of a physician.

Dietary Sources

The best dietary sources of iron are liver and other organ meats, lean red meat, poultry, fish, and shellfish (particularly oysters). Iron from these sources is readily absorbed in the intestines.

Other sources of iron include dried beans and peas, legumes, nuts and seeds, whole grains, dark molasses, and green leafy vegetables. However, iron from these sources must be accompanied by certain nutrients for proper absorption. For example, vitamin C helps the absorption of this type of iron while calcium (including all dairy products), bran, tea, and unprocessed whole grain products block its absorption.

In the U.S. grain products such as breads and cereals are fortified with iron.

Available Forms

Ferrous sulfate is the most common type of iron supplement. Other available forms include ferrous fumarate, ferrous succinate, ferrous gluconate, ferrous lactate, ferrous glutamate, and ferrous glycine.

In severe cases of anemia from low levels of iron, or if there is rapid blood loss leading to iron deficiency, iron and blood will be administered intravenously in a hospital setting.

How to Take It

Daily dietary recommendations for iron are listed below.


  • Infants birth to 6 months: 0.27 mg
  • Infants 7 to 12 months: 11 mg
  • Children 1 to 3 years: 7 mg
  • Children 4 to 8 years: 10 mg
  • Children 9 to 13 years: 8 mg
  • Males 14 to 18 years: 11 mg
  • Females 14 to 18 years: 15 mg


  • Males 19 years and older: 8 mg
  • Females 19 to 50 years: 18 mg
  • Females 51 years and older: 8 mg
  • Pregnant females: 27 mg
  • Breastfeeding females 14 to 18 years: 10 mg
  • Breastfeeding females 19 years and older: 9 mg


Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable healthcare provider.

The most common side effect from iron supplements is stomach upset including discomfort, nausea, diarrhea, constipation, and heartburn.

Although not entirely clear, there may be an association between high iron stores and risk of heart disease, cancer (such as breast cancer), and Alzheimer's disease. Similarly, for those with inflammatory bowel disease (Crohn's disease and ulcerative colitis) the areas of the bowel that are inflamed appear to have higher amounts of iron. This is thought to be because iron acts as a pro-oxidant, stimulating the damaging effects in the body of substances known as free radicals.

Iron overload disease, although most commonly an inherited condition called hemochromatosis, may occur in people who consume excessive amounts of iron over a long period of time. Symptoms include skin discoloration, diabetes, and liver damage, amongst other potential complications. The FDA has established that taking up to 45 mg of iron per day is safe. However, safety for amounts higher than 45 mg per day is not known. Severe iron overdose occurs when amounts of iron equivalent to 50 or 100 times greater than the recommended dietary dose are ingested. Such iron toxicity can lead to destruction of cells in the gastrointestinal tract, which can cause vomiting, bloody diarrhea, and even death. Given the severity of potential adverse effects from excessive iron, supplements should be kept in childproof bottles and out of the reach of children.

Intravenous iron, administered in the case of severe anemia in a hospital setting, can lead to headache, fever, swollen lymph nodes, painful joints, hives, worsening of rheumatoid arthritis, and in rare instances a life-threatening allergic reaction known as anaphylaxis.

Possible Interactions

If you are currently being treated with any of the medications discussed below, you should not use iron without first talking to your healthcare provider.

Iron may interfere with the absorption of many different medications. For this reason, it is best to take iron supplements at least two hours before or two hours after taking medications. This is particularly true for the medications listed below.

The following medications may reduce the absorption of iron:

  • Cholestyramine and Colestipol: These are two cholesterol-lowering medications known as bile acid sequestrants.
  • Medications used to treat ulcers or other stomach problems: Examples of anti-ulcer medications include cimetidine, ranitidine, famotidine, and nizatidine. These medications belong to a class of drugs known as H2 receptor blockers. They change the pH in the stomach and subsequently alter the absorption of iron. It is possible that this effect could occur with other antiulcer medications including antacids and proton pump inhibitors (such as omeprazole and lansoprazole).

Iron decreases the absorption of the following medications:

  • Tetracyclines: These are a class of antibiotics that include doxycycline, minocycline, and tetracycline.
  • Quinolones: These are a class of antibiotics that include ciprofloxacin, norfloxacin, ofloxacin, and levofloxacin.
  • ACE inhibitors: These are a class of medications used to treat high blood pressure. Examples include captopril, enalapril, and lisinopril.

Iron may reduce the effectiveness or blood levels of the following medications:

  • Carbidopa and Levodopa: Iron lowers blood levels of these medications but it is unclear whether these changes lower the effectiveness of the drugs.
  • Levothyroxine: Iron may decrease the effectiveness of this thyroid replacement hormone. A healthcare practitioner should monitor thyroid function closely in those taking iron supplements with thyroid medications.

Iron levels may be increased by:

  • Birth control medications

Supporting Research

Akerele JO, Okhamafe AO. Influence of oral co-administered metallic drugs on ofloxacin pharmacokinetics. J Antimicrob Chemother. 1991;28:87-94.

Balfour JA, Wiseman LR. Moxifloxacin. Drugs. 1999;57(3):363-374.

Baumgaertel A. Alternative and controversial treatments for attention-deficit/hyperactivity disorder. Pediatr Clin of North Am. 1999;46(5):977-992.

Belton N. Iron deficiency in infants and young children. Professional Care of Mother and Child. 1995;5:69-71.

Brouwers J. Drug interactions with quinolone antibacterials. Drug Safety. 1992;7(4):268-281.

Campbell NR, Hasinoff BB, Meddings JB, Anderson WD, Robertson S, Granberg K. Ferrous sulfate reduces cimetidine absorption. Dig Dis Sci. 1993;38(5):950-954.

Christen Y. Oxidative stress and Alzheimer disease. Am J Clin Nutr. 2000;71(suppl):621S-629S.

Dayal M, Barnhart KT. Noncontraceptive benefits and therapeutic uses of the oral contraceptive pill. Semin Reprod Med. 2001;19(4):295-303.

Duffy SJ, Biegelsen ES, Holbrook M, et al. Iron chelation improves endothelial function in patients with coronary artery disease. Circulation. 2001;103(23):2799-2804.

Fleming DJ, Jacques PF, Dallal GE, et al. Dietary determinants of iron stores in a free-living elderly population: the Framingham Heart Study. Am J Clin Nutr. 1998;67:722-733.

The Food and Nutrition Information Center. National Agricultural Library (NAL), United States Department of Agriculture's (USDA) Agricultural Research Service (ARS). Accessed at on January 8, 1999.

Hercberg S, Preziosi P, Galan P. Iron deficiency in Europe. Public Health Nutr. 2001;4(2B):537-545.

Hines Burnham T, et al, eds. Drug Facts and Comparisons. St. Louis, MO:Facts and Comparisons;2000:1294.

Hinton PS, Giordano C, Brownlie T, Haas JD. Iron supplementation improves endurance after training in iron depleted, nonanemic women. J Appl Physiol. 2000;88(3):1103-1111.

Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press. January 9, 2001. Accessed May 6, 2002 at

Jensen JT, Speroff L. Health benefits of oral contraceptives. Obstet Gynecol Clin North Am. 2000;27(4):705-721.

Kara M, Hasinoff BB, McKay DW, et al. Clinical and chemical interactions between iron preparations and ciprofloxacin. Br J Clin Pharmacol. 1991;31(3):257-261.

Lee SC, Park SW, Kim DK, Lee SH, Hong KP. Iron supplementation inhibits cough associated with ACE inhibitors. Hypertension. 2001;38(2):166-170.

Li RC, Lo KN, Lam JS, et al. Effects of order of magnesium exposure on the postantibiotic effect and bactericidal activity of ciprofloxacin. J Chemother. 1999;11(4):243-247.

Liehr JG, Jones JS. Role of iron in estrogen-induced cancer. Curr Med Chem. 2001;8(7):839-849.

Lih-Brody L, Powell Sr, Collier KP, et al. Increased oxidative stress and decreased antioxidant defenses in mucosa of inflammatory bowel disease. Dig Dis Sci. 1996;41(10):2078-2086.

Mason P. Nutrition and Dietary Advice in the Pharmacy. Oxford, UK: Blackwell Scientific; 1994:234-235.

Neuvonen PJ. Interactions with the absorption of tetracyclines. Drugs. 1976;11(1):45-54.

Okhamafe AO, Akerele JO, Chukuka CS. Pharmacokinetic interactions of norfloxacin with some metallic agents. Int J Pharmaceutics. 1991;68:11-16.

Physicians' Desk Reference. 55th ed. Montvale, NJ: Medical Economics Co., Inc.; 2001:587-591, 847-860.

Recommendations to Prevent and Control Iron Deficiency in the United States. Atlanta, Ga: Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report; April 3, 1998;47(RR-3):1-29.

Say AE, Gursurer M, Yazicioglu MV, Ersek B. Impact of body iron status on myocardial perfusion, left ventricular function, and angiographic morphologic features in patients with hypercholesterolemia. Am Heart J. 2002;143(2):257-264.

Schaefer JP, Tam Y, Hasinoff BB, et al. Ferrous sulphate interacts with captopril. Br J Clin Pharmacol. 1998;46(4):377-381.

Sempos C, Looker AC, Gillum RE, McGee DL, Vuong CV, Johnson CL. Serum ferritin and death from all causes of cardiovascular disease: The NHANES II Mortality Study. Ann Epidemiol. 2000;10(7):441-448.

Sever Y, Ashkenazi A, Tyano S, Weizman A. Iron Treatment in children with attention deficit Hyperactivity disorder: a preliminary report. Neuropsychobiology. 1997; 35:178-180.

Shakir KM, Chute JP, Aprill BS, Lazarus AA. Ferrous sulfate-induced increase in requirement for thyroxine in a patient with primary hypothyroidism. South Med J. 1997;90(6):637-639.

Sturniolo GC, Mestriner C, Lecis PE, et al. Altered plasma and mucosal concentrations of trace elements and antioxidants in active ulcerative colitis. Scand J Gastroenterol. 1998;33:644-649.

Torkos S. Drug-nutrient interactions: a focus on cholesterol-lowering agents. Int J Integrative Med. 2000;2(3):9-13.

Tyrer LB. Nutrition and the pill. J Reprod Med. 1984;29(7 Suppl):547-550.

Tzonou A, Lagiou P, Trichopoulou A, et al. Dietary iron and coronary heart disease: a study from Greece. Am J Epidemiol. 1998;147:161-166.

Review Date: April 2002
Reviewed By: Participants in the review process include: Ruth DeBusk, RD, PhD, Editor, Nutrition in Complementary Care, Tallahassee, FL; Jacqueline A. Hart, MD, Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University and Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh (Pediatric Dosing section February 2001), Johnson Drugs, Natick, Ma; Steven Ottariono, RPh (Pediatric Dosing section February 2001), Veteran's Administrative Hospital, Londonderry, NH. All interaction sections have also been reviewed by a team of experts including Joseph Lamb, MD (July 2000), The Integrative Medicine Works, Alexandria, VA;Enrico Liva, ND, RPh (August 2000), Vital Nutrients, Middletown, CT; Brian T Sanderoff, PD, BS in Pharmacy (March 2000), Clinical Assistant Professor, University of Maryland School of Pharmacy; President, Your Prescription for Health, Owings Mills, MD; Ira Zunin, MD, MPH, MBA (July 2000), President and Chairman, Hawaii State Consortium for Integrative Medicine, Honolulu, HI.

Copyright © 2004 A.D.A.M., Inc

The publisher does not accept any responsibility for the accuracy of the information or the consequences arising from the application, use, or misuse of any of the information contained herein, including any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise. No warranty, expressed or implied, is made in regard to the contents of this material. No claims or endorsements are made for any drugs or compounds currently marketed or in investigative use. This material is not intended as a guide to self-medication. The reader is advised to discuss the information provided here with a doctor, pharmacist, nurse, or other authorized healthcare practitioner and to check product information (including package inserts) regarding dosage, precautions, warnings, interactions, and contraindications before administering any drug, herb, or supplement discussed herein.

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