With oral iron therapy, rise in Hb% can be seen after:

Rise in hemoglobin with oral iron – 0.7 gm-1 gm per week, which is seen after 3 weeks of initiation of oral therapy. (According to COGDT, 10/ed, p 407 — Hemoglobin levels should increase by atleast 0.3g/dl/week if the patient is responding to therapy) If there is no significant clinical or hematological improvement within 3 weeks, diagnostic re-evaluation is needed.