A nurse is collecting data from a client who is at 20 weeks of gestation and has been taking ferrous sulfate. For which of the following findings should the nurse monitor as a common adverse effect of iron supplementation and report to the provider?

Ferrous sulfate is commonly prescribed during pregnancy to prevent or treat iron deficiency anemia caused by increased maternal blood volume and fetal iron demands. Although effective, oral iron supplements frequently produce gastrointestinal adverse effects that can affect adherence to therapy. Nurses should educate clients about expected side effects and monitor for complications that may require intervention. Recognizing common versus abnormal effects helps promote safe use and appropriate reporting. Rationale: A. Dry mouth is not a common adverse effect of ferrous sulfate therapy. Iron supplements primarily affect the gastrointestinal tract, leading to symptoms such as constipation, nausea, abdominal discomfort, and dark stools. Dry mouth is more commonly associated with medications that have anticholinergic properties rather than oral iron therapy. B. Tinnitus is not an expected adverse effect of iron supplementation and is more commonly associated with medications such as salicylates or ototoxic drugs. Ferrous sulfate does not typically affect the auditory system. If tinnitus occurs, the nurse should consider other causes rather than attributing it to routine iron therapy. C. Hematuria is not a common side effect of ferrous sulfate and may indicate urinary tract pathology such as infection, trauma, or renal disease. Iron supplements may darken the stool but should not cause blood in the urine. This finding would require further evaluation for causes unrelated to routine supplementation. D. Constipation is a common adverse effect of ferrous sulfate because iron slows gastrointestinal motility and can make stools harder to pass. Pregnant clients are already at increased risk due to hormonal changes and decreased bowel motility, making this effect more significant. The nurse should monitor bowel patterns, encourage fluids and fiber intake, and report persistent constipation that affects comfort or adherence.