After administering morphine sulfate for chest pain, what should the nurse do if the client feels dizzy 15 minutes later?

The appropriate action in this scenario is to place the client in the supine position. When a client feels dizzy after administering morphine sulfate, it may indicate the onset of hypotension or other side effects related to the medication. By positioning the client supine, which means lying flat on their back, blood flow to vital organs such as the brain is improved, potentially alleviating dizziness and preventing a fall.

In this situation, monitoring the client’s vital signs and observing for any changes in their condition are also essential. While placing the client in a sitting position might seem like a reasonable option to ease discomfort, it could exacerbate dizziness by reducing venous return to the heart and brain. Administering additional fluids or calling a physician immediately are not the first responses unless assessed to be necessary based on the client's overall condition. The focus should be on stabilizing the patient in this situation.