Key Points about Swelling

  • Swelling occurs when excess fluids are trapped in the body’s tissues, which causes the affected organs, skin, or other body part to enlarge.
  • Swelling can be internal or external. 
  • Internal swelling is often caused by organ inflammation, fluid retention, or flatulence.
  • External swelling can be caused by acute injuries, insect bites, rashes, hormonal changes, and infections.
  • Localized swelling can usually be treated at home.
  • Swelling that affects large areas of the body or the whole body may signal a serious underlying illness and requires immediate medical attention.

Overview

Swelling occurs when excess fluids are trapped in the body’s tissues, which causes the affected organs, skin, or other body part to enlarge. A variety of conditions can cause swelling, from acute injuries to insect bites. 

Swelling can be internal or external. Most cases of external swelling can be treated at home with ice, or with medications such as antihistamines or anti-inflammatories, depending upon the swelling’s location. Swelling that is widespread throughout the body or does not respond to at-home treatments may be a sign of a serious underlying medical condition. Call your doctor if your swelling is present throughout your whole body, worsens over time, or does not respond to treatment. 

Swelling causes

Swelling occurs when excess fluids are trapped in the body’s tissues and can be internal or external. External swelling can be caused by:

  • Muscle injury
  • Insect bites
  • Rashes
  • Acute injuries
  • Pregnancy, menstruation, and hormonal changes
  • Infection
  • Inflammation

There are two types of external swelling: localized and widespread. Localized swelling affects just one area of the body—for example, swelling surrounding the area after a bee sting—while widespread swelling affects large areas of the body. 

Widespread swelling usually signals a serious underlying illness, and can be a symptom of:

  • A serious allergic reaction, or anaphylaxis
  • Kidney failure
  • Heart failure
  • Fluid retention
  • A venomous bite from an insect
  • Diabetes
  • Certain forms of cancer

Internal swelling is often caused by:

  • Organ inflammation
  • Fluid retention
  • Flatulence

Swelling risk factors

Being affected by any of the conditions listed above may increase your risk of experiencing swelling. 

Swelling symptoms

Swelling is marked by puffiness and can be internal or external. Depending on the cause of your swelling, you may have a range of additional symptoms. Or, swelling could be your only symptom. 

Swelling diagnosis

Your doctor will perform a physical examination and review your symptoms to determine the cause of your swelling. 

Imaging tests can provide additional insight into the cause. These tests may include:

  • Ultrasound
  • CT scan
  • MRI

These tests can help identify broken bones, inflamed tissues or muscles, or any blockages in your veins and arteries. 

You doctor may also test your blood and urine to see if your swelling is a symptom of an existing illness. 

Swelling treatment

Treatment for swelling depends on its location and cause. Antihistamines and topical steroids can relieve swelling caused by hives or rashes.

If over-the-counter treatments do not help, your doctor may prescribe additional medications to alleviate swelling. 

Your doctor will also treat any underlying condition that is causing the swelling. 

When to seek care

Seek medical attention if your swelling:

  • Is accompanied by a fever
  • Gets worse over time
  • Is sudden, and you are pregnant

Next Steps

Your doctor can refer you to an additional specialist if the condition causing your swelling requires treatment.