Iron Supplements - Side Effects

Side Effects

Side effects of therapy with oral iron are most often diarrhea or constipation and epigastric abdominal discomfort. Taken after a meal, side effects decrease, but there is an increased risk of interaction with other substances. Side effects are dose-dependent, and the dose may be adjusted.

The patient may notice that his/her stools become black. This is completely harmless, but patients must be warned about this to avoid unnecessary concern. When iron supplements are given in a liquid form, teeth may reversibly discolor (this can be avoided through the use of a straw). Intramuscular injection can be painful, and brown discoloration may be noticed.

Treatments with iron(II) sulfate have higher incidence of adverse events than iron(III)-hydroxide polymaltose complex (IPC) or iron bis-glycinate chelate.