Final answer:
The nurse should monitor for nausea, diarrhea, vomiting, and changes in blood pressure and heart rate.
Step-by-step explanation:
The nurse should monitor for nausea, diarrhea, vomiting lasting 24-48 hours, and possible dehydration and changes in blood pressure and heart rate after administering hydrochlorothiazide and digoxin to a patient. Hydrochlorothiazide is a diuretic medication that can cause gastrointestinal symptoms, while digoxin is a cardiac medication that can affect blood pressure and heart rate.