Reducers of preload These aid in lowering the pressure caused by fluid entering your heart and lungs. Diuretics also aid in lowering blood pressure by causing you to pee, which removes fluid. The urine flow will also flush out any drug particles that might be circulating through your body. Diuretics can be administered orally or injected intramusselty. The most common oral diuretic is hydrochlorothiazide (Zetia, Zoloft). Lasix is another name for furosemide, which is an oral diuretic used to treat high blood pressure, congestive heart failure, and edema (excessive accumulation of fluid in the body). In addition to reducing preload, diuretics can also reduce afterload by limiting the amount of salt and water in the body. This reduces the workload on the heart during each contraction. Reducer of afterload After a person has been deprived of fluid for several hours, even if the deprivation is only temporary, the plasma volume becomes reduced. This means there is less fluid outside the cells to fill with salt and water, so more fluid is drawn into the cells to make up for the loss. This extra fluid inside the cells increases their weight and pressure, putting stress on the heart muscle. As long as this stress is only internal, such as from increased blood volume, the heart muscle can handle it.