Chlorothiazide is the active ingredient of Diuril Oral Suspension and is frequently prescribed to those experiencing high blood pressure, also known as hypertension. As a diuretic, Diuril Oral Suspension will work by increasing the amount of sodium and fluid your kidneys excrete which causes you to urinate more than usual. Diuril Oral Solution also helps your blood vessels to dilate so a proper blood flow occurs and there’s less strain on your heart.