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March 2017

Which Iron Supplement Should You Recommend?

It's tricky to iron out differences among oral iron supplements. Efficacy and tolerability are similar at equal doses of elemental iron. But the percent of elemental iron varies between products.

For iron deficiency, expect most patients to need 100-200 mg/day elemental iron. Suggest ferrous sulfate or fumarate. These typically have 65-100 mg elemental iron/tab versus about 35 mg with ferrous gluconate.

Products containing more elemental iron can cause more GI upset and constipation. Suggest starting with just one tab per day and titrating up to twice daily or three times daily over a week or two. Also explain that iron is best absorbed on an empty stomach, but it's okay to take it with food if GI upset occurs. If needed, offer strategies to limit GI upset, such as switching to a product with less elemental iron. Or consider once-daily dosing as an option, but it may take longer to correct an iron deficiency with a lower dose.

Vitamin C slightly increases iron absorption, but most combo products don't have enough vitamin C to make a difference. Don't feel compelled to recommend other iron forms. Explain that slow-release or enteric-coated products may not be absorbed as well because they dissolve later in the GI tract. Also point out that there's no proven advantage to using more costly iron forms, such as polysaccharide-iron complex (Ferrex 150, etc), carbonyl iron (ICAR), or heme iron polypeptide (Proferrin ES, etc).

Check our Commercial Products Database for details on specific iron supplements.

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