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What is inflammation?

Regardless of the actual cause, the body responds in a typical manner by increasing the blood supply to the injured area, thus delivering an increased number of white blood cells to the affected tissue.

The blood vessels become permeable, in other words their walls allow white blood cells, proteins, and fluid to leak through. These white blood cells will endeavour to eliminate the offending agent by what is called phagocytosis – a process whereby white blood cells surround and ingest germs, foreign objects, or dead cells to enable their removal. This is then followed by down-regulation of these activities resulting in healing. This process is the so-called cascade of inflammation, and it is the body’s unique mechanism to maintain its integrity1,2,3.

The body’s immune system is responsible for the inflammatory response2.

Inflammation is best viewed as a defence mechanism that helps one recover from infection and injury. However, it may also produce unpleasant sensations, such as pain, swelling, bruising or redness2,3. Such discomfort is usually temporary and will disappear when healing has been completed. Sometimes, however, inflammation may cause harm and tissue damage may occur3.

Types of inflammation

Inflammation can be divided into two types2:

Acute inflammation

This is your body’s immediate response to an injury or illness. It starts rapidly and becomes severe quickly2,4,5. If the inflammation subsides in less than 48 hours, it is called acute inflammation2,4.

Chronic inflammation

If the body is unable to eliminate the causative agent, or if there is some interference with the healing process, an acute inflammatory response may progress to the chronic stage3. Chronic inflammation may also result from repeated episodes of acute inflammation3. It is a long-term condition that can last for several months and even years4,5. Its extent, duration, and effects are determined by the cause of the injury and the body’s ability to ameliorate the damage3.

The period between acute and chronic inflammation is called subacute inflammation and this may last 2 to 6 weeks5.

Signs of inflammation

Acute inflammation

The four cardinal signs of acute inflammation were first described by the Roman medical writer Aulus Cornelius Celsus in the 1st century AD and are easy to identify3,4:

  1. Redness (Latin rubor) – caused by the dilation of small blood vessels in the injured area
  2. Heat (calor) – resulting from the increased blood flow through the area
  3. Swelling (tumor) – from the leakage of fluid
  4. Pain (dolor) – partly due to the swelling which causes distortion of tissues, but also brought about by the chemical mediators of inflammation (known as prostaglandins and bradykinin, amongst others) that enhance the sensitivity of the affected tissues to pain.

There is also a fifth consequence of inflammation, and this is loss of function (function laesa) in the inflamed area. It may result from pain and/or swelling that prevent or limit mobility3.

Chronic inflammation

Symptoms of chronic inflammation are more subtle and may include5:

  • Body pain, such as joint or muscle pain
  • Constant fatigue and insomnia
  • Mood disorders, such as depression and anxiety
  • Gut complaints, such as constipation, a runny stomach (diarrhoea) or acid reflux
  • Weight gain or weight loss
  • Regularly getting infections.

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Causes of inflammation

Acute inflammation is the body’s complex, dynamic, protective response to cell injury, infection (with bacteria, viruses, or other micro-organisms), trauma or toxins4.

Chronic inflammation can result from several processes all characterised by the inability to complete the healing process. These may involve any of the following5:

  • The body’s defence mechanisms may be unable to eliminate the microorganisms causing an infection and they thus stick around, continuing to infect the tissue. Examples of microorganisms that can resists the body’s defences include tuberculosis, certain fungi, and other parasites.
  • The body experiences prolonged exposure to a low level of a particular irritant that cannot be eliminated by its usual mechanisms (such as enzymatic breakdown and phagocytosis), for example inhalation of industrial chemicals such as silica dust over a long period.
  • An autoimmune disorder, where the body mistakenly identifies its own tissue and organs as foreign bodies and launches an inflammatory attack against them, for example rheumatoid arthritis or systemic lupus erythematosus.
  • A defect in the cells that are meant to mediate (or wind down) inflammation leading to persistent or recurrent inflammation. An example of such an auto-inflammatory disorder is Familial Mediterranean Fever.
  • Repeated episodes of acute inflammation.  However, chronic inflammation does not always get triggered by acute inflammation; it can exist on its own, as is the case with rheumatoid arthritis or tuberculosis.
  • Signalling molecules in the body may cause cells to malfunction and produce more inflammation-causing substances.

Risk factors for chronic inflammation

There are several factors that may promote a low-level inflammatory response and that may increase one’s likelihood of developing chronic inflammation, including2,5:

  • Age – Levels of inflammatory molecules tend to increase as we age and this may be due to cell dysfunction or the accumulation of harmful substances known as free radicals (unstable atoms that are highly reactive).
  • Obesity – Studies have shown that fat acts as an endocrine organ in the body, secreting multiple substances including inflammatory mediators which promote inflammation.
  • Diet – Diets rich in saturated fat, trans-fats or refined sugar have been linked to higher levels of pro-inflammatory molecules, especially in people with diabetes or those who are overweight.
  • Smoking – Cigarette smoking induces inflammation and also suppresses the molecules responsible for mediating or winding down inflammation.
  • Stress – Both physical and emotional stress have been linked to an increase in inflammation-causing proteins.
  • Poor sleep – People who have irregular sleep patterns are more likely to have chronic inflammation than consistent sleepers.
  • Low levels of sex hormones – Hormones like testosterone and oestrogen have been shown to suppress the production and secretion of pro-inflammatory molecules.

Complications of chronic inflammation

Chronic inflammation has very detrimental consequences and chronic inflammatory diseases are ranked as the most significant cause of death in the world5. Examples of specific diseases mediated by chronic inflammation include5:

  • Diabetes
  • Heart disease
  • Arthritis and joint disorders
  • Allergies
  • Chronic obstructive pulmonary disease (COPD or emphysema).


Unlike the easy recognisable signs of acute inflammation, chronic inflammation is more challenging.

Chronic inflammation is usually only diagnosed in association with another medical condition. There are several blood tests, ranging from inexpensive to quite costly, to help your doctor confirm the presence of chronic inflammation and its possible cause5.

When to see your doctor about inflammation?

Any worrisome injury should prompt you to contact your healthcare provider. Ongoing pain, swelling, stiffness, or other symptoms should also be investigated2. Fever or significant symptoms, such as severe pain or shortness of breath, should also be reported to your doctor6.


Acute inflammation

Acute inflammation does not always require treatment. However, rest, ice, and good wound care often provide adequate relief from discomfort in a few days2. Over-the-counter (OTC) pain relievers or anti-inflammatories may also help to relieve symptoms. In certain instances, it is important to treat the cause of the inflammation. A bacterial infection, for example, will require treatment with antibiotics6. If in doubt, it is always best to consult your doctor.

Chronic inflammation

To effectively address chronic inflammation, a combination of medical treatment and lifestyle interventions is usually required5. Weight loss alone has been shown to be highly effective5.

Treatment options

Medical treatment for chronic inflammation includes:

Non-steroidal anti-inflammatory drugs (NSAIDs): These medicines reduce inflammation and many are available over the counter. Examples include ibuprofen, diclofenac, and naproxen2. They are mostly used to provide pain relief5.

Corticosteroids: Medicines such as prednisone, prednisolone and hydrocortisone offer rapid anti-inflammatory activity, especially in instances where organ function is threatened by whole-body inflammation. They are associated with serious adverse effects, however, when used orally in high doses or long-term1,2. An alternative to oral therapy is local steroid injections to address inflammation limited to a particular area, such as a joint or muscle2.

Immunomodulators: Hydroxychloroquine is an example of an immunomodulator that reduces autoimmune activity without compromising the individual’s ability to fight infections. While originally developed to treat malaria, it has been shown to effectively reduce inflammatory symptoms in patients with autoimmune conditions such as systemic lupus erythematosus and Sjogren’s syndrome. Other examples in include salazopyrine (especially for rheumatoid arthritis), dapsone (for cutaneous lupus), and macrolide antibiotics (for allergic and other forms of chronic bronchitis)1.

Antigen-specific immunotherapy: This therapy is also known as desensitisation. It allows the body to acclimatise to a well-defined, relevant allergen through repeated exposure in small doses over a period of time. It may be particularly helpful for allergic inflammatory conditions, such as asthma and hay fever1.

Metformin: This antidiabetic medicine also has anti-inflammatory activity and is commonly used to treat type 2 diabetes5.

Statins: Traditionally used to lower high blood cholesterol levels, statins are also able to reduce multiple circulating and cellular mediators of inflammation. In doing so, these medicines help to reduce the risk of heart attacks5.

Supplements and herbal medicines: Vitamins A, C, and D, zinc, fish oil supplements and herbal remedies such as turmeric (curcumin) ginger or garlic may also help to reduce inflammation2,5. They should only be used or combined with orthodox medicines under the supervision of a healthcare practitioner.


Lifestyle interventions are key for preventing and managing chronic inflammation5. The following interventions have been shown to be useful5:

  • Follow a low glycaemic diet by limiting the consumption of inflammation-promoting foods like sodas, refined sugars, fructose, and corn syrup.
  • Reduce the intake of total, saturated and trans-fats.
  • Eat more fruit and vegetables, such as blueberries, apples, Brussels sprouts, cabbage, broccoli, and cauliflower. These fruits and vegetables are high in natural antioxidants and polyphenols and other anti-inflammatory compounds.

Increase the intake of dietary fibre and nuts (which may lower one’s risk of heart disease and diabetes).