Side effects of oral iron (Fe) therapy

Side effects of oral iron therapy are a common problem. Usually side effects are due to excess oral iron. Excess oral iron can affect almost all the body system. Gastrointestinal irritation is common and it occurs with iron salts like ferrous sulphate and ferrous fumarate. Nausea and epigastric pain are another common side effects of oral iron therapy and are dose related but the relationship between oral iron dose and altered bowel habits (constipation and diarrhea) is less clear. Oral iron, particularly modified release preparations, may exacerbate diarrhea in patients with inflammatory bowel disease. Care is also needed in patients with intestinal strictures and divertcula.

Oral iron preparation may be constipating, particularly in older patients, occasionally leading to fecal impaction.

If side effects occur, the dose may be reduced; alternatively, another iron salt may be used but an improvement in tolerance may simply be a result of a lower content of element iron. The incidence of side effects due to ferrous sulphate is no greater than with other iron salts when compared on the basis of equivalent amounts of element iron.

Oral iron preparations are an important cause of accidental overdose in children