What are the 3 stages of inflammation?

Phases of  inflammation

1. Vascular phase(0-12 hours)

2. Cellular phase(12-72 hours) 

3. Resolution phase(48-96 hours after peak response to injury/ insult)

The three stages of inflammation are initiation, resolution, and chronic inflammation. Initiation is the first step in the process, during which an acute-phase protein is synthesized. Resolution involves restoring tissue homeostasis and is induced by cytokines such as IL-10 and TGF-β. Chronic inflammation occurs when excessive or unresolved inflammatory responses prolong cellular responses and lead to damage of host tissues (e.g., as seen with chronic infections).

stages of inflammation
stages of inflammation

Vascular phase

This is the first response of our immune system to invading pathogens. It is a protective mechanism that involves vasodilation, increased permeability, and blood flow to tissues as well as migration of immune cells to the site of injury where they fight against infection. This acute inflammatory reaction is a very fast process involving white blood cells called neutrophils, monocytes, eosinophils, and basophils. 

It is usually successful in neutralizing the pathogen but it can also cause tissue damage once the battle is over. During this stage of inflammation, certain pro-inflammatory messengers are released which prepare other parts of our body for the upcoming fight against pathogens. These messengers are called cytokines and they include TNF-α, IL-1β, interferons, and chemokines.

Cellular phase

This is the second step of the inflammatory process which occurs after the first wave of chemicals have been released to fight against an invader. This period can last for several days or even weeks. The pro-inflammatory cytokines are still present but now immune cells such as macrophages and lymphocytes are also recruited to clear the remaining pathogens. The proinflammatory cytokines during this phase include IL-6, IL-18, IFN-γ, and TNF-β.

Resolution phase

This is a stage of inflammation that occurs after all pathogens have been eliminated from the infected tissue. During this stage, inflammatory cells are no longer present in the tissue. Repair of the damaged tissue occurs and any pathogens that might have been missed by the first round of immune cells are now chewed up by macrophages. It is during this stage of inflammation that anti-inflammatory cytokines such as IL-10 and TGF-β are released to minimize the tissue damage.

Chronic inflammation

This is a long-lasting inflammation that occurs in response to chronic stress, toxins, and autoimmunity. During this stage of inflammation, immune cells are still present in tissues and they can even become more aggressive than usual which results in severe tissue damage (e.g., as seen with autoimmune diseases). Chronic inflammatory cytokines include IL-6, TNF-α, IFN-γ and IL-17.

Inflammation is an essential part of our immune system which helps us fight against infection. However, without proper regulation, it can cause severe damage to our own tissues. This is why the 3 stages of inflammation are important for returning the body to a healthy state after it has fought an infection.


It is crucial to distinguish between these 3 stages of inflammation and the fact that many people confuse them by calling any symptom which causes redness or pain "inflammation". For example, headaches are not caused by inflammation but because of vasodilation in the brain. As such, anti-inflammatory drugs such as ibuprofen are not going to help. In general, symptoms of redness and pain indicate acute inflammation while symptoms such as fatigue suggest chronic inflammation.

Resolution is the third stage of inflammation during which pro-inflammatory cytokines decrease and anti-inflammatory cytokines increase in order to restore tissue homeostasis.

What is the strongest anti-inflammatory medication?

Salicylic acid is the strongest over-the-counter anti-inflammatory medication. Salicylic acid belongs to a group of drugs called salicylates. It works by increasing the turnover of cells in the outer layer of skin, reducing swelling, and helping relieve pain caused by conditions such as osteoarthritis.

What are the benefits of taking anti-inflammatory medication?

Anti-inflammatory medications reduce inflammation, which helps to reduce stiffness and joint pain. They can also help to relieve pain such as headaches and toothache. Some people take them regularly to prevent painful flare-ups of conditions such as Crohn's disease or rheumatoid arthritis. 

Other people take them for very short periods (often as a rescue treatment) if they think they are about to suffer an asthma attack or a bout of rhinitis.

What is the difference between anti-inflammatory and pro-inflammatory?

Anti-inflammatory medications reduce inflammation, which helps to reduce stiffness and joint pain. They can also help to relieve pain such as headaches and toothache. Some people take them regularly to prevent painful flare-ups. Other people take them for very short periods.

Pro-inflammatory medications increase inflammation, which helps to fight infections. You may be given pro-inflammatory medication if you have an infection or after surgery. They will make you feel generally unwell for a while because they cause many of the symptoms of flu, such as aches and pains, headache, and fever. 

What are the side effects of anti-inflammatory medication?

Side effects usually wear off after a few days. Side effects of salicylic acid include:

  • Skin irritation, such as redness, itching, and dryness
  • Nausea and indigestion
  • Salicylate toxicity 
  • Headache 
  • Ulceration of the esophagus (food pipe) and stomach lining. This can be very serious and is more common in people who have a history of oesophageal problems, such as heartburn.

Corticosteroids can cause:

  • Stomach ulcers, which may be serious and lead to stomach bleeding. Stop taking this medicine and see your doctor straight away if you get any sign of bleeding from your stomach or bowels, such as vomiting blood or passing black/tarry stools.

  • Corticosteroids may make you more prone to getting infections, such as coughs and colds (especially if you are taking them for your asthma). Taking corticosteroid tablets long-term can make it harder for your body to combat infections. You can reduce this risk by regularly taking a probiotic supplement.

  • Corticosteroids can affect your blood pressure or make it more likely for you to have a stroke. You should be checked for high blood pressure before being prescribed this medicine and monitored regularly by your doctor.

  • If you suffer from asthma, corticosteroid tablets may make it worse initially but in the long term, they often help keep your asthma under control.

  • Corticosteroid tablets can make you more likely to have cataracts, glaucoma, or diabetes. Check with your doctor that you are not at risk of these conditions before being prescribed this medicine.

  • Aspirin may cause indigestion and stomach upset, especially if taken on an empty stomach. Do not take aspirin if you are allergic to it.

Other side effects may include:

  • Feeling sick and vomiting 

  • Changes in your taste

  • Dizziness or ringing in the ears (tinnitus) 

  • Problems with your circulation, such as Raynaud's syndrome, blood clots, and strokes 

Whilst taking NSAIDs you should avoid drinking too much alcohol.

Your doctor, nurse, or pharmacist will tell you exactly how many tablets to take and for how long. Take painkillers at the recommended dose and frequency and do not take more than the maximum daily dose of each drug in 24 hours. Always read the leaflet that comes with your medicine packet.

Anti-inflammatory medicines may not be suitable for people with certain medical conditions, or women who are pregnant or breastfeeding. You should speak to your doctor before taking this medicine if you have any of the following conditions:

  • Heart disease 

  • Liver disease 

  • Kidney disease 

  • Stomach ulcers, irritable bowel syndrome, or inflammatory bowel disease 

  • Rheumatoid arthritis or other autoimmune conditions 

  • Asthma, especially if you are taking corticosteroids. If you have problems with your breathing, check with your doctor that this medicine is safe to take before being prescribed it.

  • Anti-inflammatory medicines may not be suitable for people who are breastfeeding, pregnant, or planning pregnancy.

  • If you develop a skin rash, vomiting, diarrhea, or if your asthma gets worse after starting this medicine, contact your doctor for advice. If you notice any other side effects not listed above, tell your doctor or pharmacist.