Edema, the medical term for swelling, is the body's natural response to injury and has many causes, according to WebMD. Common causes for mild edema include sitting too long, pregnancy and drug side effects, states the Mayo Clinic. Causes for severe edema include heart failure and kidney disease.
Common injuries that may cause edema include twisted ankles, skin infections and bug bites, notes WebMD. The response is beneficial if an infection is present, because it allows a higher number of white blood cells to reach and fight the infection.
Drugs that are known for causing edema include high blood pressure medication, steroids and estrogens. Other causes of severe edema include liver damage, vein damage in the legs and an inadequate lymphatic system.
Treatment for edema depends greatly on the specific cause of the condition. Mild edema generally goes away on its own, and raising the affected body part above the heart may help, according to the Mayo Clinic. Severe edema can often be treated with drugs that expel excess fluid through the urinary tract. Long-term treatment requires curing or managing the underlying cause of edema, such as changing to a drug that does not have edema as an associated side effect.