Key takeaways

  • Swelling, which can be internal or external, is the body’s response to inflammation, fluid buildup, injury, or illness.
  • Visible signs of swelling include enlargement of the affected area and fluid retention. Doctors can identify internal swelling through imaging tests.
  • Treatment options range from lifestyle changes and medication to surgery, depending on the cause and severity of the swelling.

Swelling occurs whenever the organs, skin, or other parts of your body enlarge. It’s 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, and injuries often result in external swelling. Internal swelling is often a side effect of a medication or the result of organ dysfunction or serious injury.

You should seek immediate medical attention if you experience rapid, unexplained swelling, especially if you also experience unexplained weight gain and pain.

Sometimes, instances of slight swelling may go unnoticed. Swelling doesn’t 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 include:

  • itching
  • redness or warmth in the affected area
  • pain in the affected area

If the swelling isn’t visible or if it’s internal, you may experience the following symptoms:

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:

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’s often due to fluid retention or an allergic reaction.

Other common causes of widespread swelling include:

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 your body, swelling is often the result of organ inflammation or fluid retention. This can occur in people with chronic diseases such as irritable bowel syndrome, Crohn’s disease, and cancer.

Your doctor may do a variety of tests to diagnose your swelling and its cause. First, they will go over the symptoms you’re experiencing and perform a physical examination to check for tenderness in the affected area.

An imaging test, such as an ultrasound, can offer more information about the cause of the swelling. More specialized tests, such as a CT scan or MRI, may also provide information on the cause of the swelling.

Imaging tests might reveal:

  • blockages in your arteries and veins
  • inflamed muscle or tissue
  • bone fractures

They can also show if you’re retaining fluid or have an impacted colon. And your blood and urine will be tested to determine if a disease is causing the swelling.

If a severe allergic reaction is causing your swelling, you’ll be given an injection of adrenaline before any tests are administered. This medication will stop the reaction from getting any worse.

Your treatment will depend on the cause of the swelling. If a tumor or abscess is causing the swelling, you may need surgery to remove it.

If the growth can’t be surgically removed because of its size or location, your doctor may order an aggressive treatment, such as chemotherapy or radiation, to shrink it.

Your doctor might also prescribe medication to relieve inflammation or swelling. Over-the-counter antihistamines can relieve itching and swelling caused by rashes or hives.

Topical steroid medication may also be useful in easing skin inflammation. Consult with your doctor if these medications don’t help. They may be able to prescribe a stronger antihistamine.

If a chronic illness is causing external or internal swelling, you may be able to prevent further swelling by properly managing your illness or by taking medications to treat it. Medication is also used when you have internal swelling as a result of inflammation.

Your doctor may also suggest lifestyle changes to prevent internal swelling. Some at-home measures you can take include:

  • decreasing salt intake
  • wearing support hose
  • keeping your arms and legs above chest level when lying down

Swelling isn’t always cause for concern. Minor swelling or swelling that results from an obvious cause, such as a bug bite or rash, may be treatable with home remedies alone.

However, there are certain cases where swelling may be the result of a serious health concern and require a conversation with a doctor. Consider reaching out to a medical professional if your swelling:

  • has no clear cause
  • has not improved after treating it at home for a few days
  • gets worse

You should consider seeking immediate medical attention if your swelling:

  • has no clear cause
  • is painful or develops quickly
  • is red or warm to the touch
  • occurs with shortness of breath
  • occurs alongside a high temperature or fever symptoms
  • occurs in the feet or lower legs in those with diabetes

Swelling is a common physiological response with many potential causes. Generally, it results from inflammation or a buildup of fluid within the body.

Swelling may be visible, affecting the outer layers of skin and the muscles. But it may also occur internally and only be identified through imaging tests.

The treatment for swelling depends on the underlying cause. Some causes of swelling respond to rest and home remedies, while others may require medication or more involved treatments.

Consider speaking with a doctor if swelling is severe or has no obvious cause.