06/01/2026
⚠️ The cardinal signs of acute inflammation ⚠️
Did you know, Aulus Cornelius Celsus (25 BC-50 AD), a Roman encyclopedist, offered a still valid statement about inflammation: “Notae vero inflammationis sunt quatuor: rubor et tumor cm calore and dolore”, defining the four cardinal signs of inflammation as redness and swelling with heat and pain.
There are four (plus one more) physiological signs of acute inflammation. These are:
Rubor (redness)
🔷 Cause: increased blood flow (hyperemia) to the affected area due to the dilation of small blood vessels (arterioles and capillaries).
🔷 Why it happens: the body sends more blood to deliver immune cells and nutrients to the site of injury or infection.
Tumor (swelling)
🔷 Cause: accumulation of fluid (edema) in the tissues.
🔷 Why it happens: blood vessels become more permeable, allowing plasma proteins and white blood cells to leave the bloodstream and enter the tissue, which helps fight infection and start repair, but also causes swelling.
Dolor (pain)
🔷 Cause: release of chemicals (like prostaglandins and bradykinin) that stimulate nerve endings.
🔷 Why it happens: these chemicals sensitise nerves, making the area more sensitive to pain. Swelling can also physically press on nerves, contributing to discomfort.
Calor (heat)
🔷 Cause: increased blood flow to the area raises the local temperature.
🔷 Why it happens: the warmth is a direct result of more blood (which is warmer than surrounding tissues) being delivered to the site.
Functio laesa (loss of function)
🔷 Cause: the four effects of inflammation as stated above.
🔷 Why it happens: the four effects combine to create a temporary loss of function.
These physiological changes are part of the body’s defence mechanism. They help bring immune cells, antibodies and nutrients to the site of injury or infection, and facilitate the removal of debris and pathogens.
Once the threat is eliminated and repair is underway, these changes subside, and the tissue gradually returns to normal.