5 Signs of Inflammation

Learn about the causes and signs of inflammation

Inflammation has many causes, including infections, injuries, and diseases. Signs of inflammation help healthcare providers in making a diagnosis. Five cardinal signs characterize this response: pain, heat, redness, swelling, and loss of function. In some cases, though, there may be no symptoms of inflammation at all.

This article describes two types of inflammation—acute and chronic—and details the five signs. It also discusses additional signs and complications of inflammation, as well as treatment options.

Five cardinal signs of inflammation
Verywell / JR Bee.

What Is Inflammation?  

Inflammation is a complex process involving a variety of cell and signaling proteins that protect the body from infection and foreign substances, such as bacteria and viruses. Inflammation helps the body by producing white blood cells, which your body needs to fight infection.

Sometimes, the immune system triggers an inflammatory response inappropriately. This is the case with autoimmune diseases. The body compensates by attacking its own healthy tissues, acting as if they are infected or abnormal.    

When the inflammation process starts, chemicals in white blood cells are released into the blood and the affected tissues to protect the body. The chemicals increase blood flow to the infected or injured body areas, causing redness and warmth. 

These chemicals may also cause leaking of fluids into tissues, resulting in swelling. This protective process can also stimulate nerves and tissues, causing pain. 

Types of Inflammation

Acute Inflammation

Acute inflammation may include heat (sometimes from fever) or warmth in the affected area. 

Acute inflammation is a healthy and necessary function that helps the body attack bacteria and other foreign substances in the body. Once the body has healed, inflammation subsides. 

Examples of conditions that cause acute inflammation include:

  • Acute bronchitis, which causes inflammation of the airways that carry air to the lungs
  • An infected ingrown toenail
  • A sore throat related to the flu
  • Dermatitis includes skin conditions like contact dermatitis, such as from poison ivy or nickel. It tends to be acute and self-limited.
  • Physical trauma
  • Sinusitis, which can cause short-term inflammation in the membranes of the nose and surrounding sinuses (usually the result of a viral infection)
  • Skin cuts and scratches

Chronic Inflammation

Chronic inflammation may continue to attack healthy areas if it doesn't "turn off." It may not be as visible as acute inflammation.

Some chronic inflammatory conditions include:

  • Inflammatory arthritis, which covers a group of conditions distinguished by inflammation of joints and tissues (including rheumatoid arthritis, lupus, and psoriatic arthritis)
  • Asthma, which causes inflammation in the air passages that carry oxygen to the lungs. Inflammation causes these airways to become narrow and breathing to become difficult. 
  • Periodontitis, which causes inflammation of gums and other supporting teeth structures. It is caused by bacteria triggered by local inflammation.
  • Inflammatory bowel disease (IBD), which, like Crohn’s disease and ulcerative colitis, causes signs of inflammation in the gut (gastrointestinal tract)
  • Eczema is from chronic skin inflammation that causes red, itchy inflamed rashes in areas where the skin flexes (such as inside the elbows and behind the knees)

Signs of Inflammation

The five cardinal signs of inflammation. They may differ in the organs that they affect, but signs of inflammation in the heart and other sites of the body share much in common.

Pain

With both acute and chronic inflammation, inflammatory chemicals can stimulate nerve endings, causing the affected areas to feel more sensitive.

Inflammation can cause pain in joints and muscles. When inflammation is chronic, a person will experience high levels of pain sensitivity and stiffness. The inflamed areas may be sensitive to touch. 

Heat

When inflamed areas of the body feel warm, it is because there is more blood flow in those areas.

People with arthritic conditions may have inflamed joints that feel warm to the touch. The skin around those joints, however, may not have the same warmth. Whole-body inflammation may cause fevers as a result of the inflammatory response when someone has an illness or infection.  

Redness 

Inflamed areas of the body may appear red because the blood vessels of inflamed areas are wider than usual.

Swelling 

Swelling, or edema, is common when a part of the body is inflamed. It results from fluid accumulating in tissues either throughout the body or in the affected area. Swelling may cause pressure on the skin and other tissue, leading to pain.

Swelling can occur without inflammation, especially with injuries. 

Loss of Function         

Inflammation may cause loss of function related to both injury and illness. For example, an inflamed joint may not move properly, or a respiratory infection causing signs of inflammation in the lungs may make it difficult to breathe. 

Acute inflammation occurs at the onset of an injury that lasts for several days. It involves two components:

  • The cellular component, in which first-line white blood cells called leukocytes and macrophages are activated and recruited to the site of the injury
  • The vascular phase, in which blood vessels dilate (open) and tissues swell to accommodate the rapid influx of immune cells and antimicrobial chemicals

What Are Cytokines?

Cytokines released into the bloodstream lead to increased vascular permeability, or the ability of molecules to pass through blood vessels and reach tissue. Cytokines are molecules that encourage your cells to communicate with each other. A healthy immune system depends on them.

Additional Signs and Complications

When inflammation is severe, it may cause additional signs and symptoms, including:

  • Exhaustion
  • Fever
  • A general feeling of sickness 
  • Trouble sleeping

Inflammation due to illness may have dangerous complications, including a condition called sepsis. This occurs when the body's immune system overwhelmingly responds to a serious infection, which leads to generalized, life-threatening tissue damage.

Causes

The causes of inflammation are extensive but can be broadly classified as:

  • Biological, such as infections, diseases, and abnormal immune responses (including autoimmune diseases, atopy, allergy, and drug hypersensitivity)
  • Chemical, including poisons, toxins, and alcohol
  • Physical, such as injuries, burns, frostbite, or radiation exposure

Diagnosing Inflammation

No single test can diagnose inflammation or the conditions that cause it. Instead, based on your symptoms, your healthcare provider will decide which tests may be needed.

First, your healthcare provider will take a complete medical history and conduct a physical examination. They may also request bloodwork and imaging studies.

Blood Tests

Blood tests can look for certain biological markers that indicate inflammation is present. However, these tests are considered informative rather than diagnostic. They help give your healthcare provider clues as to what’s going on.

Tests your healthcare provider may request include:

  • C-reactive protein (CRP): CRP is a protein naturally produced in the liver in response to inflammation. High levels of CRP are common in people with chronic inflammation, inflammatory diseases, and acute inflammation.
  • Erythrocyte sedimentation rate (ESR): ESR testing is usually done to identify whether inflammation is occurring. This level is usually high with certain chronic inflammatory diseases, like lupus.

Imaging

Imaging modalities that can detect inflammation include:

  • MRI with gadolinium enhancement
  • Ultrasound with power doppler
  • FDG PET-CT
  • Nuclear imaging

Treatment 

Treatment will depend on the specific disease or ailment and the severity of symptoms.

Acute Inflammation

For general inflammation, your healthcare provider may recommend:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs are usually the first-line treatment for short-term pain and inflammation. Most of these medications are available over the counter (OTC), including aspirin, ibuprofen, and naproxen. Your healthcare provider can also prescribe prescription-strength NSAIDs for certain inflammatory conditions. Certain people should not take NSAIDs (even OTC NSAIDs), such as those with a history of chronic kidney disease or on anticoagulation.
  • Corticosteroids: This is a type of steroid commonly used to treat swelling and inflammation. Corticosteroids are available in pill form and as injections. These drugs are only prescribed for short periods, since they are known to cause serious side effects.
  • Topical medications: Topicals, including analgesics and steroids, can help with acute and chronic pain and inflammation of the skin and joints, without the side effects of oral treatments. They are also helpful for managing long-term inflammation when they contain an NSAID, such as diclofenac or ibuprofen.

If inflammation is caused by a bacterial infection, antibiotics may be necessary.

Chronic Inflammation

In addition to treating joint pain and inflammation, medications for inflammatory diseases can help to prevent or minimize disease progression.

Medications may include:

  • Disease-modifying anti-rheumatic drugs (DMARDs), including Rheumatrex (methotrexate), Azulfidine (sulfasalazine), and Arava (leflunomide)
  • Biologic drugs, such as Enbrel (etanercept), Humira (adalimumab), and Orencia (abatacept)
  • Anti-malarial drugs, such as hydroxychloroquine
  • Statins
  • Diabetes medications

Because many medications used to treat inflammatory diseases can cause harsh side effects, it is important to see your healthcare provider regularly.

Preventing Chronic Inflammation

There are several lifestyle changes you can make to prevent and reverse chronic inflammation. These include:

  • Getting at least 20 minutes of moderate exercise per day
  • Employing stress-reduction techniques like mindfulness meditation
  • Quitting smoking
  • Maintaining a healthy weight
  • Following an anti-inflammatory diet

Summary

Inflammation occurs as your body fights infection. And as it wages the fight, you may experience pain, heat, redness, swelling, and loss of function.

The symptoms are common enough, but it's still smart to learn the differences between acute and chronic inflammation. It probably will make a difference in how your particular case of inflammation is treated.

A Word From Verywell

Inflammation is a necessary part of the healing process and usually nothing to worry about. But when inflammation is chronic, it can be a serious health problem. See your healthcare provider to identify the source of the inflammation. It's the first step toward proper treatment.

Frequently Asked Questions

  • What can I drink to reduce inflammation?

    Water, tea, coffee, milk, acidic juices, smoothies, and moderate amounts of alcohol (specifically red wine) can help fight inflammation. Avoid sugary drinks and sodas.

  • What are the worst foods for inflammation?

    Anti-inflammatory foods to avoid include white bread and pastries made with refined flours, fried foods (including potatoes), red and processed meats, like beef and sausage, and margarines.

  • Can inflammation affect internal organs?

    Over time, chronic inflammation can cause changes in organs that may increase the risk of heart attack, cancers, and other age-related diseases. Chronic inflammation is associated with chronic condition like diabetes, heart disease, COPD, or HIV.

  • How do you test for inflammation?

    Testing for inflammation will depend on your healthcare provider's assessment and what the suspected source may be. Blood tests, allergy skin tests, and gastrointestinal (GI) procedures are just a few of the possible tests.

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By Lana Barhum
Lana Barhum has been a freelance medical writer since 2009. She shares advice on living well with chronic disease.