You gotta find out what causes your ankle and foot swelling in the first place. The most common causes are:
Venous insufficiency. Swelling of the ankles and feet is often an early symptom of venous insufficiency, a condition in which blood inadequately moves up the veins from the legs and feet up to the heart. Normally, the veins keep blood flowing upward with one-way valves. When these valves become damaged or weakened, the blood leaks back down the vessels and fluid is retained in the soft tissue of the lower legs, especially the ankles and feet. Chronic venous insufficiency can lead to skin changes, skin ulcers, and infection. If you experience signs of venous insufficiency you should see your doctor.
Blood clot. Blood clots that form in the veins of the legs can stop the return flow of blood from the legs back up to the heart and cause swelling in the ankles and feet. Blood clots can be either superficial (occurring in the veins just beneath the skin), or deep (a condition known as deep vein thrombosis). Deep clots can block one or more of the major veins of the legs. These blood clots can be life-threatening if they break loose and travel to the heart and lungs. If you have swelling in one leg, along with pain, low-grade fever, and possibly a change in color of the affected leg, call your doctor immediately. Treatment with blood thinners may be necessary.
Heart, liver, or kidney disease. Sometimes swelling can indicate a problem such as heart, liver, or kidney disease. Ankles that swell in the evening could be a sign of retaining salt and water because of right-sided heart failure. Kidney disease can also cause foot and ankle swelling. When kidneys are not functioning properly, fluid can build up in the body. Liver disease can affect the liver's production of a protein called albumin, which keeps the blood from leaking out of the blood vessels into the surrounding tissues. Inadequate albumin production can lead to fluid leakage. Gravity causes fluid to accumulate more in the feet and ankles, but fluid can also accumulate in the abdomen and chest. If your swelling is accompanied by other symptoms, including fatigue, loss of appetite, and weight gain, see your doctor right away.