Diuretic drugs are medications that help the kidneys remove excess fluid from the body, helping to lower blood pressure and decrease edema and fluid overload. They do this by stimulating the kidneys to excrete sodium (salt). Sodium molecules associate with water, so when they're eliminated by the kidneys, they take water with them. This reduces the amount of excess fluid in the blood and in the body. Heart failure often gives rise to fluid overload, and people with heart failure are commonly treated with diuretic drugs. Recent evidence suggests, however, that long-term, aggressive use of diuretics in patients with heart failure may not be prudent.
As heart failure progresses, a number of symptoms related to fluid overload can appear. Excess fluid can enter the tiny air sacs in the lungs and reduce the amount of oxygen that can enter the blood, causing shortness of breath (dyspnea). Fluid can accumulate in the lungs when a patient lies down at night and make nighttime breathing and sleeping difficult (orthopnea), or even cause the patient to wake up suddenly gasping for air (paroxysmal nocturnal dyspnea). Fluid overload can also occur in the lower limbs and/or abdomen. One million people are hospitalized each year in the United States for heart failure, 90 percent of them for symptoms related to fluid overload.