An infection is an illness caused by harmful bacteria, viruses or other germs getting into the body. Inflammation is a reaction where part of the body turns red, swollen, hot and painful, usually in response to an injury or an infection. A chest infection is caused by germs; the inflammation in a sprained knee is the body's response to the injury itself, with no germs involved.
The core difference
An infection is caused by germs entering the body; inflammation is the body's reaction, which can happen with or without an infection.
- infection — an illness caused by harmful bacteria, viruses or other germs: She was put on antibiotics to treat a chest infection.
- inflammation — redness, swelling, heat and pain as a reaction to injury or infection: The doctor prescribed an anti-inflammatory to reduce the inflammation in his knee.
How to tell them apart
The two often appear together because an infection can trigger inflammation as the body fights it off, but they are not the same thing. Inflammation can happen on its own, from an injury or a chronic condition, with no infection involved at all.
A simple way to keep them straight: infection is about the cause, germs getting in; inflammation is about the effect, the body's redness, swelling and pain. Chronic inflammation, unlike infection, has been linked to a range of long-term illnesses even without any germs present.
