Iron deficiency anemia is one of the most common types of anemia, but real-world clinical management practices in Japan are unclear. This study retrospectively explored iron prescription patterns, treatment effectiveness, and assessments. Patients with at least one treatment period between September 2020 and September 2022 were included and classified into three groups (ferric carboxymaltose [FCM]: 7437 patients, saccharated ferric oxide [SFO]: 98,648 patients, and oral iron: 359,547 patients). Iron-related laboratory values over time and testing proportions were evaluated. Median baseline hemoglobin levels were lowest with FCM (FCM: 8.10 g/dL, SFO: 8.70 g/dL, oral iron: 9.70 g/dL), but changes in hemoglobin levels by 12 weeks were greatest with FCM (FCM: 3.20 g/dL, SFO: 2.60 g/dL, oral iron: 1.70 g/dL). The median serum ferritin level at 8 weeks after FCM treatment was 43.70 ng/mL for ≤500 mg, versus 123.30 ng/mL for >500 to ≤1500 mg. All groups had a low proportion of serum ferritin and transferrin saturation (TSAT) testing at diagnosis (<38%), which decreased further for post-treatment assessment (<24%). This study suggests the importance of prescribing an appropriate total iron cumulative dose per the package insert, along with diagnosis and assessments based on serum ferritin/TSAT.