Mild HTN. If the BP can be controlled without a diuretic, then none need be used. However, normal physiologic response to BP lowering is to retain fluid, so a diuretic makes great sense, acting synergistically with other BP meds. Moreover, diuretics complement the potassium retaining effect of some BP drugs by clearing potassium in the urine. Hctz (hydrochlorothiazide) is so gentle, you won't even know it's working-i promise!