swelling

Edema, also known as swelling, is the abnormal accumulation of watery fluid in the body's tissues. This excess fluid is essentially an ultrafiltrate of serum, though it may contain small amounts of protein. Edema can be a localized issue or a generalized condition affecting body cavities, a state historically referred to as dropsy.12

This condition is typically a symptom of an underlying disease rather than a disease itself. Common causes include issues with the kidneys, heart, veins, or lymphatic system, as well as malnutrition or allergic reactions. For instance, swelling in the brain is called cerebral edema, and fluid buildup in the lungs is known as pulmonary edema.13

The inflammatory response, a non-specific defense mechanism, can also lead to swelling. This occurs when chemicals released by macrophages increase capillary permeability, allowing fluid and cells to enter tissues, causing pain and swelling. Treatment for edema generally involves addressing the root cause.41