Side Effects of Intravenous Iron and Iron Overload

As a transition metal, iron has a dual personality. Iron is an essential nutrient — good — or it can be a dangerous toxin — bad.

Intravenous iron, or IVI, is recommended when someone has iron deficiency anemia and cannot get enough iron from her diet or iron supplements. People with chronic kidney disease are most commonly given IVI, although this treatment may be recommended for people with another condition that reduces iron absorption from the intestines.

Iron is normally administered as a complex with other molecules to make it more stable in the blood. The earliest approved preparations were iron sucrose, iron gluconate and iron dextran. The amount of iron given per injection is about 100 mg for these products.

Newer Food and Drug Administration-approved iron preparations include ferric carboxymaltose, another sugar complex, and ferumoxytol, an iron carbohydrate complex. These forms of IVI may be administered at doses of roughly 500 to 750 mg of iron in a single infusion.

The most serious problem associated with injection of IVI products is a severe allergic reaction to the injection called anaphylaxis. This is a sudden response affecting the entire body, which sometimes happens to people who are allergic to peanuts or beestings. The signs and symptoms of anaphylaxis include dizziness or fainting, skin flushing and itchiness, difficulty breathing, rapid heart rate, low blood pressure and sudden anxiety.

FDA researchers reviewed voluntary reports submitted to the agency of serious, anaphylactic-like reactions associated with IVI through mid-2007. Their findings were reported in a September 2010 article published in the "American Journal of Hematology."

The authors note that 3 or fewer confirmed deaths occur annually in the U.S. related to an anaphylactic reaction to IVI. Administration of iron dextran appears to have a higher rate of anaphylaxis compared to other intravenous iron products, according to the report authors.

Gastrointestinal symptoms that are seen with IVI include nausea, vomiting and diarrhea. Nausea is the most common symptom with newer agents but occurs in less than 7 percent of patients, according the manufacturers' prescribing information.

Low blood pressure is the most common side effect associated with injection of iron sucrose and iron gluconate. Other symptoms include chest pain, abdominal cramps and shortness of breath. Less common side effects include dizziness, loss of the sense of taste, fluid buildup and pain in the back or extremities.

With prolonged use, intravenous iron may lead to iron overload in the tissues, which is a dangerous condition. Iron overload can be toxic to all body systems.

Signs and symptoms of iron overload include tiredness, irregular heartbeat and heart failure, joint pain, loss of fertility, erectile dysfunction and change in skin color. The liver is a primary site of iron overload and may begin to fail as iron accumulates. Use of IVI requires careful monitoring to avoid iron overload.