Swelling occurs whenever the organs, skin, or other parts of your body enlarge. It is typically the result of inflammation or a buildup of fluid. Swelling can occur internally, or it can affect your outer skin and muscles. A range of conditions can cause swelling. Insect bites, illnesses, or injuries often result in external swelling. Internal swelling is often a side effect of medication or the result of a serious injury. You should seek immediate medical attention if you experience rapid, unexplainable swelling, especially if you also experience unexplained weight gain and pain.

Symptoms of swelling
Sometimes, instances of slight swelling may go unnoticed. This condition does not always cause other symptoms. For external swelling, the enlargement of skin or muscles is usually visible. However, other signs of swelling include the buildup of fluid in the affected area. An imaging scan can show an enlarged organ, muscle, or bone. A scan can help diagnose internal swelling, which is harder to identify. If your swelling was caused by an injury, sting, or disease, you might experience a wide range of symptoms. These may include: itching, vomiting, flatulence, pain in the affected area. If the swelling is not visible or if it is internal, you may experience the following symptoms: nausea, vomiting, dizziness, fever, fatigue, Insomnia, flu-like symptoms, pain.

What causes swelling?
Inflammation in your bones, tissues, or muscles can result in external swelling. Cysts and tumors may also cause visible swelling. Although fluid retention is an internal condition, it may also cause external swelling. The most common causes for external swelling include: insect bites, rash, hives, injury, fluid retention, pregnancy, menstruation, hormonal changes, infection.

External swelling can be localized or widespread.
Localized swelling refers to situations where just one specific area is swollen. For example, a person with an eye infection may experience swelling only around the eyes. A person who has been stung by an insect may experience swelling only in the area of the sting.

Widespread swelling occurs over a large area of the body.
This is usually a sign of serious illness. It is often due to fluid retention or an allergic reaction. Other common causes of widespread swelling include:
-- Hemophilia
-- Kidney Failure
-- heart failure
-- anaphylaxis (severe allergic reaction)

People with diabetes or certain forms of cancer can experience widespread swelling, or swelling in their extremities, such as their fingers and toes. This form of swelling may appear periodically. Inside of your body, swelling is often the result of organ inflammation, fluid retention, or flatulence. This can occur in people with chronic diseases such as Irritable Bowel Syndrome, Crohn’s Disease, and cancer.