Confusing labels on iron supplements: A problem that still needs to be “ironed” out


When an elderly man developed anemia, his physician advised the man’s daughter to give him 325 mg of ferrous sulfate (iron) tablets daily. Ferrous sulfate is taken to treat iron-deficiency anemia, a condition in which the body does not have enough healthy red blood cells due to low levels of iron in the body. The man’s daughter bought a bottle of “iron ferrous sulfate” from the pharmacy. The label said each tablet contained 65 mg (Figure 1, on page 1 of the PDF version), so she gave her father 5 tablets daily believing this would equal a 325 mg dose. However, each tablet actually contains 65 mg of elemental iron, which is equal to 325 mg of ferrous sulfate. Unfortunately, the label did not clearly state that each tablet contains 325 mg of ferrous sulfate. The information on the back of the label under Supplement Facts is also confusing. That part of the label says each tablet contains “Iron (as Ferrous Sulfate) 65 mg.” The elderly man developed severe constipation, a common side effect of iron even when given at the correct dose. He was soon hospitalized for other reasons. During his hospitalization, the mistake was recognized while reviewing the medicines the man had been taking at home.

This is not a new problem. Longstanding confusion with the way iron supplements are labeled has led to frequent errors. And it’s not just consumers who have made errors—so have healthcare providers, including nurses and pharmacists. Most physicians prescribe iron supplements as Iron figure 1ferrous sulfate. Ferrous sulfate is the form of iron that is best absorbed by the body. As noted above, 325 mg of ferrous sulfate contains just 65 mg of elemental iron. Some iron supplement labels only list the amount of elemental iron in each tablet. Other iron supplement labels note that each tablet contains 325 mg of ferrous sulfate (Figure 2, on page 1 of the PDF version). However, mistakes have still been made because the Supplement Facts lists the amount of “Iron, as Ferrous Sulfate” in each tablet as 65 mg. Even worse, some liquid infant iron supplements do not include the amount of iron per mL at all on the front of the label (Figure 3, on page 2 of the PDF version). Instead, only the amount of elemental iron per mL is listed (15 mg), not the amount of ferrous sulfate per mL (75 mg).

iron 2 and 3

There are other forms of oral iron supplements in addition to ferrous sulfate. Two products that you can find over the counter are ferrous gluconate and ferrous fumarate. But again, the stated dose of each product is different from the actual dose of elemental iron that it contains. For example, a 324 mg tablet of ferrous gluconate contains just 38 mg of elemental iron, while a 325 mg tablet of ferrous fumarate contains 106 mg of elemental iron. Although these iron-containing products are recommended less frequently than ferrous sulfate, the labels on these products are just as confusing.

Since most iron supplements are available over-the-counter (OTC), you may purchase them in any number of places without a pharmacist’s assistance. However, please consider the following recommendations to reduce the risk of an error:

ü  If your doctor recommends an iron supplement, ask for the dose in both elemental iron and ferrous sulfate forms (e.g., elemental iron 65 mg [ferrous sulfate 325 mg]).

ü  Although iron supplements are available OTC, ask your doctor for a prescription so your pharmacist always helps you select the correct supplement. Talk to the pharmacist when you pick up the product to be sure you understand the dosing instructions.

ü  If you do not receive a prescription for an iron supplement, purchase the product at a pharmacy so you can ask a pharmacist for help, especially if purchasing liquid iron supplements for infants and children. Some pharmacies store all iron supplements behind the pharmacy counter so a pharmacist can talk to consumers about proper dosing if the product is purchased.

ü  Before you leave the pharmacy, confirm with a pharmacist how many tablets or mL of an iron supplement you plan to take (or give a loved one) to be sure you understand how to take the iron supplement correctly.

ü  Keep all iron supplements up and out of the reach of children. It may only take a few tablets to cause serious toxicity in children. If an accidental poisoning happens, call the Poison Help number (800-222-1222) immediately.

Created on August 21, 2018

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