Edema happens when tiny blood vessels in your body leak fluid. The fluid builds up in surrounding tissues, which leads to swelling. Mild cases may result from being pregnant, eating too much salty food, sitting or staying in one position for too long, or having premenstrual signs and symptoms. Edema can also be a side effect of some medications, which include estrogens, certain diabetes medications, high blood pressure medications, non-steroidal anti-inflammatory drugs. In some cases, edema just might be a sign of more serious health issues, like congestive heart failure, cirrhosis, kidney damage or kidney disease, severe, long-term protein deficiency, or damage or weakness to the veins in the legs.