In the medical world, fluid retention in the body is called oedema. This fluid build-up causes body tissue to become swollen, and it can occur in a localised part of the body, such as the ankles or feet, or it can be more general. This is often the case with oedema that results from health conditions such as heart or kidney failure.
When oedema occurs in the feet or ankles, it may be the result of particular injuries and infections, or it may result from systemic conditions such as obesity or pregnancy. Diseases of the joints, such as arthritis, can also lead to swelling in the ankle and foot. In such cases, treatment depend on the cause.
These depend on the underlying cause, and can range from a (usually painless) increase in foot and ankle size, to changes of skin colour/texture. Other symptoms may include warm skin and ulceration.
There are many causes of swollen feet and ankles. These include:
- Long periods of standing or walking.
- Medications: many medications, such as steroids and NSAIDs, have a side effect of fluid retention (which results in swelling).
- Injury: traumas such as sprains or fractures can result in swelling.
- Diseases: heart disease, liver disease and kidney disease can all affect the way fluid moves around the body.
- Infection: any infection, either localised (abscess) or diffuse (cellulitis).
- Lymphedema: blockage of lymph vessels or nodes can cause swelling.
- Blood clot(s): blockage of blood vessels can cause fluid to leak out of vessels into tissue.
This is highly dependent on an accurate diagnosis of the underlying cause(s). Often, though, the condition can be improved by raising the legs above the heart while lying down. You should also avoid sitting or standing (without moving) for long periods, or wearing clothing that could constrict blood flow in the upper legs. Exercise (involving the legs) will help get fluid back into the veins and reduce swelling. Reducing salt intake may also help reduce fluid retention.