Fluid accumulation and inflammation stemming from an underlying health condition causes swollen legs, as explained by Mayo Clinic, and an injury resulting from an accident, fall or sports-related activity can also cause legs to swell. People with peripheral edema may also experience a hard, heavy and tight feeling in their legs, according to Parent Giving.
Leg swelling related to fluid accumulation may result from hormone therapy, deep vein thrombosis, heart failure and the use of pain relievers such as naproxen and ibuprofen, according to Mayo Clinic. The accumulation of fluid that leads to swollen legs also results from acute kidney failure, diseases of the heart tissue, blockages in the lymphatic system and damage to blood vessels in the kidney. Chronic kidney disease, cirrhosis, pregnancy and certain medications for high blood pressure as well as diabetes may cause fluid retention that leads to swollen, hard legs.
Inflammation that causes legs to swell may be caused by injuries such as a sprained ankle, a broken foot or leg, an Achilles tendon rupture and an ACL injury, as detailed by Mayo Clinic. People with skin infections, wounds or infections in the leg, osteoarthritis, and rheumatoid arthritis experience inflammation that can lead to swollen legs. A Baker's cyst, gout or knee bursitis may also cause inflammation and swollen legs. A medical professional should evaluate swollen legs, especially when pain, difficulty breathing and dizziness also occur.