You are caring for a client with hyperthyroidism that is taking propylthiouracil (PTU). The client reports that she misunderstood the instructions and took more doses than her prescribed dosage. The client also reported drowsiness, weight gain, edema, and cold intolerance. You suspect which of the following adverse effects of this drug?

The correct answer is A: Hypothyroidism. Propylthiouracil (PTU) is an antithyroid medication used to treat hyperthyroidism by inhibiting the production of thyroid hormones. If the client takes more than the prescribed dosage, it can suppress thyroid hormone production excessively, leading to hypothyroidism. Symptoms of hypothyroidism include drowsiness, weight gain, edema, and cold intolerance, which align with the client's reported symptoms. Other choices are incorrect as B: Thyrotoxicosis is the opposite condition of hyperthyroidism, C: Cushing's Syndrome is caused by excessive cortisol production, and D: Addison's Disease is caused by adrenal insufficiency, none of which are associated with PTU overdose.