An anti-inflammatory substance is one which counteracts inflammation. Inflammation is a response made by the immune system in response to bodily injury - whether physical trauma, infection, extremes of temperature, etc. Bloodflow is increased to the injured area, and substances are released to begin repair of damaged tissue.
The process produces side effects including redness, swelling, heat, pain, and sometimes fever. This process is normal, and an outward sign that the body's self-repair mechanisms are in force. However, if the inflammation process occurs inappropriately (as in some immune system disorders), or is too extreme or extended, an anti-inflammatory drug may be used to reduce the extent of inflammation.
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain