Instructed that medication Spironolactone is used to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. It is also used to treat swelling (edema) caused by certain conditions (e.g., congestive heart failure) by removing excess fluid and improving symptoms such as breathing problems. Instructed that common side effects include, Drowsiness, dizziness, lightheadedness, stomach upset, diarrhea, nausea, vomiting, or headache.