What do systematic reviews say?

Intravenous iron vs oral iron

Intravenous iron therapy may leads to higher haemoglobin levels at end of preoperative treatment (g/dL) compared with oral iron therapy (low certainty).

• Iron therapy for preoperative anaemia 2019 · Cochrane Headline outcomes only
  MD 1.23 [0.8, 1.65]
  2 studies · 172 participants
  Low