What commonly causes leg swelling and what to do about it?

Leg swelling. One sided: could be a blood clot, an infection. Both legs: could be a weak heart (unable to pump blood well), liver disease (low albumin), kidney disease (so many of them), venous (vein) insufficiency. Is better to see your doctor .
Many causes and RX. Leg swelling is a common complaint with many causes including problems with the heart, lungs or kidneys, as well as medications, lymphedema, dvt, cellulitis, venous insufficiency and a host of other issues. There is also a difference in cause if the swelling is one side or bilateral. There are many treatments for swelling but the first step is to identify the cause. See a vein specialist or md.