Inclusion Criteria:  Age 9 years or greater and less than age 22 years Heavy menstrual bleeding, defined as a Pictorial Blood Assessment Chart (PBAC) Score >100 Iron deficiency anemia, defined as both hemoglobin <12 g/dL and ferritin <15 ng/mL within 7 days of enrollment.  Exclusion Criteria:  non-uterine cause of vaginal bleeding pregnancy chronic kidney disease serology confirmed celiac disease active gastrointestinal blood loss active malignancy inability to follow-up at Texas Children's Hospital receipt of intravenous iron within 30 days prior to enrollment allergy or known inability to tolerate oral iron