Why Do Our Bodies Swell?

Swelling, also known as edema, is the name for an increase in size or change in shape of an area of the body.

Swelling is a symptom of a variety of conditions, but there is always an underlying cause. Sometimes, the source of swelling can be serious and require immediate medical attention.

So, if you notice a swollen area on your body, it’s important to identify the reason.

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Types of Swelling

Body parts swell when the body retains fluid or collects it in a certain tissue, joint, or other area. Swelling can be internal or external, localized or generalized.

  • External swelling, typically affecting skin or muscles, is visible and usually due to an insect bite, illness, or injury and commonly will heal on its own within two weeks.
  • Internal swelling, which affects organs or other areas inside the body, usually has a more serious cause and can have more intense pain.
  • Localized swellingrefers to swelling in just one area of the body, such as from a bee sting or an ankle sprain.
  • Generalized swelling affects the whole body and often is the result of a major traumatic injury or allergic reaction.

Reasons for Swelling

There can be many causes of swelling:

  • Injury– Swelling often occurs at the site of injuries – including strikes to the body, sprains, muscle strains, and bone fractures – because small tears in the surrounding blood vessels cause fluid to leak into the area.
  • Infection– Pockets of pus or other fluids may form at the site of an infection. These fluids may actually help to resolve the infection, as their presence indicates that infection-fighting white blood cells are on the job.
  • Allergic reaction– Large areas of the body may swell during an allergic reaction, which requires medical attention, especially if swelling of the face, tongue, or throat occurs.
  • Burns/chemical burns – Burns cause tender, inflamed skin with or without a blister, depending on the depth of the burn.
  • Insect bites– Most insect stings and bites result in redness and swelling. If extreme swelling, redness, and itching occur, you may be having an allergic reaction to the bite.
  • Inflammation– Joints or tendons may swell after repeated motion or overuse.
  • Autoimmune/chronic diseases– Chronic illnesses may cause circulation problems that result in the buildup of fluid throughout the body.
  • Pregnancy– Pregnant women often experience swelling of the hands and feet, especially as pregnancy progresses.
  • Menstruation– Many women retain fluid during menstruation, resulting in swelling or bloating.
  • Standing, sitting, or walking for a long time in the heat – All may cause swelling of the lower legs and feet.
  • Medications — Some common medications may cause swelling, including NSAIDs (ibuprofen, naproxen sodium) and steroids.
  • Surgery– Some swelling is normal after surgery at the site of an incision or affected area.
  • Other serious medical conditions — including cirrhosis, liver/kidney disease, and heart disease.

How to Treat Swelling

Often, swelling will go down on its own over time. You can take steps to help reduce swelling.

  • Get plenty of rest to protect the affected area.
  • Elevate the swollen area to above your heart.
  • Move the swollen area to help get blood flow back to the heart, especially if the swelling is in the legs.
  • Use pressure either from compression stockings or sleeves or simply apply pressure with your hands in a massage-like fashion.
  • Reduce the amount of salt you are consuming as it may play a role in increased swelling.
  • For more serious swelling, the underlying cause may need to be treated by doctors. An exam and/or imaging tests can help determine issues.
  • Your doctor may be able to prescribe medication or recommend other methods to reduce the swelling.

Your doctor will likely ask you questions such as:

  • Have you experience edema before?
  • Have you experienced shortness of breath as well?
  • Do you drink alcohol?
  • Are your symptoms constant or on and off?
  • Does the severity of your swelling decrease after a night’s rest?
  • What does your diet consist of?
  • Are you urinating the same as usual?

If you notice sudden, extreme, or unexplained swelling, or if your swelling is due to a serious injury or medical condition, call your doctor or seek medical attention immediately or visit a UPMC Urgent Care location.




Editor's Note: This article was originally published on , and was last reviewed on .

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