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Taking iron supplements

Definition

Eating iron rich foods is a key part of treating anemia caused by low iron levels. You may also need to take iron supplements as well to rebuild iron stores in your body.

Information

ABOUT IRON SUPPLEMENTS

Iron supplements may be taken as capsules, tablets, chewable tablets, and liquids. The most common tablet size is 325 mg (ferrous sulfate). Other common chemical forms are ferrous gluconate and ferrous fumarate.

Ask your health care provider how many pills you should take each day and when you should take them. Taking more iron than your body needs can cause serious medical problems.

Blood counts return to normal after 2 months of iron therapy for most people. You should continue taking supplements for another 6 to 12 months to build up your body's iron stores in your bone marrow.

TIPS FOR TAKING IRON

Iron is best absorbed on an empty stomach. Yet, iron supplements can cause stomach cramps, nausea, and diarrhea in some people. You may need to take iron with a small amount of food to avoid this problem.

Milk, calcium and antacids should not be taken at the same time as iron supplements. You should wait at least 2 hours after having these foods before taking your iron supplements.

Foods that you should not eat at the same time as you take your iron include:

  • High fiber foods, such as whole grains, raw vegetables, and bran
  • Foods or drinks with caffeine

Some providers suggest taking a vitamin C supplement or drinking orange juice with your iron pill. This can help the iron absorb into your body. Drinking 8 ounces of fluid with an iron pill is also OK.

Tell your provider about all the medicines you are taking.

  • Iron tablets may cause other medicines you are taking to not work as well. Some of these include tetracycline, penicillin, ciprofloxacin, and medicines used for Parkinson's disease and seizures.
  • Medicines that reduce stomach acid will impair iron absorption and may cause iron deficiency. Your provider may suggest changing these.
  • Wait at least 2 hours between doses of these medicines and iron supplements.

SIDE EFFECTS

Constipation and diarrhea are very common. If constipation becomes a problem, take a stool softener such as docusate sodium (Colace).

Nausea and vomiting may occur with higher doses, but they can usually be controlled by taking the iron in smaller amounts. Ask your provider about switching to another form of iron rather than just stopping.

Black stools are normal when taking iron tablets. Talk to your provider right away if:

  • The stools are tarry looking as well as black
  • If they have red streaks
  • Cramps, sharp pains, or soreness in the stomach occur

Liquid forms of iron may stain your teeth.

  • Try mixing the iron with water or other liquids (such as fruit juice or tomato juice) and drinking the medicine with a straw.
  • Iron stains can be removed by brushing your teeth with baking soda or peroxide.

Keep tablets should in a cool place. (Bathroom medicine cabinets may be too warm and humid, which may cause the pills to fall apart.)

Keep iron supplements out of the reach of children. If your child swallows an iron pill, contact a poison control center right away.

References

Camaschella C. Disorders of iron homeostasis: iron deficiency and overload. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 37.

Camaschella C. Microcytic and hypochromic anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 150.

Last reviewed July 8, 2023 by Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..

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