When should IV iron be used instead of oral iron?

IV iron is preferred when oral iron fails, isn’t tolerated, or can’t be absorbed, or when rapid repletion is clinically necessary.

Common indications include:

• Intolerance to oral iron (e.g., gastrointestinal side effects, nonadherence).
• Malabsorption (e.g., celiac disease, inflammatory bowel disease, post–bariatric surgery).
• Inflammatory states with impaired intestinal iron uptake (e.g., CKD, heart failure, chronic inflammation).
• Ongoing blood loss exceeding oral replacement capacity (e.g., heavy menstrual bleeding, GI bleeding).
• Need for rapid correction (e.g., preoperative anemia, symptomatic iron deficiency, late pregnancy).
• Functional iron deficiency in patients receiving erythropoiesis-stimulating agents (CKD, oncology).

In brief:

Oral iron is first-line for most mild, uncomplicated cases. IV iron is appropriate when oral therapy doesn’t work, isn’t feasible, or isn’t fast enough.