What symptom should a nurse instruct a client on trimethoprim-sulfamethoxazole to report?

Trimethoprim-sulfamethoxazole is an antibiotic combination used to treat various infections, and it can have side effects that require monitoring. One critical symptom that a client should be instructed to report is a sore throat. This symptom can be indicative of a potentially serious adverse effect known as agranulocytosis, which is a decrease in white blood cells. This condition can significantly increase the risk of developing infections, as the body's ability to fight them is compromised.

Instructing the client to report a sore throat is vital, as it may serve as an early warning sign for the onset of a more severe condition requiring immediate medical attention. While the other symptoms listed—nausea, diarrhea, and headache—can also occur, they are more common and generally considered less alarming compared to the potential implications of a sore throat when taking this medication. Awareness and timely reporting of symptoms like a sore throat can ensure a proactive approach to managing any serious side effects.