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Swelling—The Necessary Evil

Have you ever injured yourself and noticed swelling in that area? Maybe it was right away or even the next morning, but in either instance, it can be very intimidating. Some good news, swelling can make things appear worse than they really are. While it may appear abnormal, swelling is a natural and common occurrence. This is the way that your body helps heal you and starts to make you better! Swelling at a site can be caused by many different things. For example, the knee may swell due to arthritis, an injury to a structure of the knee, or just from banging your knee on something. This article will dive deeper into swelling, including:

  •  What causes swelling?
  • What is the purpose of swelling?
  • How is swelling beneficial to you?

What is Swelling?

Swelling or “effusion” develops typically between 2 and 24 hours of the injury occurring, swelling is induced by a process of the immune system called the inflammatory response. This is a vital reaction in the body to help initiate the healing process. Immune cells already waiting in the area of the injury are stimulated to release chemicals called chemokines and cytokines

As these chemicals are being released, it does cause some pain in the region, which can be uncomfortable. But these cytokine molecules are extremely important, as they increase the size of your blood vessels around the site of the injury and change the structure of these blood vessels. With larger blood vessels, more blood can flow to the site of the injury. While the increase in blood flow will cause the redness (or purple color) and the heat you get with swelling, it is essential to healing. With more blood flow, more immune cells can move into the area of the injury to aid healing. Because the cytokine chemicals released changed the structure of the blood vessels, these immune cells can leave the blood vessels to start repairing the site of injury. All the cells and proteins leaving the blood vessels to help heal the site cause the lump commonly experienced with swelling. Fluids in your body will follow the proteins to the area. This is also known as edema.

Why is Swelling Beneficial?

As mentioned earlier, all of this is natural and expected. It is a sign that your immune system is working and doing its job correctly. The inflammatory response is one of the first lines of defense your body has and is one of the first steps in the healing process.

The immune cells (different kinds of white blood cells) that are brought to the site of injury during the inflammatory response help repair tissue in the body, remove any potentially harmful foreign substances that may have gotten into the body (if there is an open wound involved in the injury), and help close the wound if there is one. This occurs inefficiently without swelling.

Swelling also works as a protective measure. Since it is uncomfortable and painful, you are less apt to be active with the site of injury. It helps you rest the injury so that you cannot do any more damage to the area, further helping the healing process. The human body is so detailed and efficient, it truly is amazing!

While the redness, pain, heat, and swelling may be uncomfortable and frustrating, it is nothing to fret about. It is just the first step on your path to recovery. The body is doing everything it can to protect and heal you, and swelling is its way of doing this. While prolonged swelling may not always be beneficial to you, this initial response is the best thing to happen to you, even if you don’t think it at the time!

How Should you Handle Swelling?

If you are interested in learning more about swelling, stay tuned. In a future article, we will discuss some strategies to progress this initial swelling through to a good recovery.

If you have swelling from a previous injury and would like to speak to a Physical Therapist directly, click below to schedule your free discovery visit.


Murphy K, Weaver C. Janeway’s Immunobiology. 9th ed. New York, NY: Garland Science; 2017.