Q. You diagnosed a 38-year-old woman with iron deficiency anemia two weeks ago and started her treatment with two daily ferrous sulfate tablets. Today she came to your clinic complaining about nausea, vomiting, and constipation, which appeared following using the ferrous sulfate. She has no dietary restrictions and usually eats homemade food. Her body mass index is 21 kg/m2. Her lab tests show a hemoglobin of 8.9 g/dL, hematocrit of 26%, serum iron of 38 microg/dL, serum ferritin of 14 microg/L, and transferrin of 420 mg/dL. What is the best plan for her intolerance of ferrous sulfate?