Leg swelling can be caused by being overweight, being older, having a blood clot in the leg, having a leg, ankle or foot injury, or having venous insufficiency. Additionally, sitting for long periods of time, such as on an airplane or in a car, can contribute to swelling. Hormonal changes in women during their menstrual cycle or pregnancy can contribute to fluid buildup.
Leg swelling also is a symptom for a number of medical conditions, including kidney failure and disease, cardiomyopathy, heart failure, lymphedema, pericarditis, cirrhosis, or preeclampsia.
Leg swelling is also a side effect of certain medications, including antidepressants, blood pressure medicine, hormone treatments, and steroids.