Final answer:
The nurse should instruct the client to drink at least eight large glasses of water a day to prevent dehydration and flush out the bacteria.
Step-by-step explanation:
The nurse should include the information to drink at least eight large glasses of water a day during client teaching. This is because trimethoprim/sulfamethoxazole can cause certain side effects such as fever, nausea, vomiting, cramps, loss of appetite, fatigue, and bloating.
Drinking plenty of water helps to flush out the bacteria and prevent dehydration. Therefore, it is important for the client to stay hydrated by drinking a sufficient amount of water.