What is fluid retention? Fluid retention (edema) is excess fluid that collects in the tissues in your body. Most commonly, fluid retention is marked by swelling of your feet and lower legs, but swelling could also occur in your arms, hands, face, or other areas of the body. Fluid retention can be caused by a wide range of conditions and diseases. The most common cause of fluid retention is too much salt in your diet. Other significant causes include heart failure; kidney disease (includes any type of kidney problem, such as kidney stones, kidney failure and kidney anomalies); liver disease (includes any type of liver problem, such as hepatitis, cirrhosis and liver failure); side effects from certain medications, including blood pressure medications; and conditions that affect your lymph nodes. Fluid retention can be mild or severe. A mild case can happen after eating a meal that is high in salt. A severe response can occur if extra water builds up inside of your lungs, a condition known as pulmonary edema that can make it very difficult to breathe. The most common treatment for fluid retention is diuretics, which are prescribed to increase urination. These medications may help alleviate symptoms; however, it is also important to treat the underlying cause of fluid retention, such as heart failure or chronic disease. Fluid retention can accompany serious or even life-threatening conditions. Seek immediate medical care (call 911) if you have trouble breathing, chest pain or pressure, an inability to urinate, or a decrease in urination. Seek prompt medical care if you have any unexplained fluid retention or swelling that is persistent or causes you concern.