Learn About
Types of Arthritis

See More Types



Predict your joint pain level based on the local weather.

Stay Connected

btn-sc-social-community btn-sc-social-facebook btn-sc-social-twitter btn-sc-social-youtube btn-sc-social-newsletters



Get the practical information you need to live better with arthritis delivered straight to your inbox!

Arthritis Today

How to reduce pain, find the right treatments and live better with arthritis. [Bi-weekly]

Fitness + Nutrition

Get weight-loss tips, arthritis-friendly recipes and ways to exercise safely. [Bi-weekly]

Mind, Body, Spirit

Find arthritis care tips, inspirational stories and Arthritis Foundation news. [Monthly]

Research Update

Discover advancements made by Arthritis Foundation-funded researchers. [Quarterly]

OA Insider

Beyond the basics of osteoarthritis: research, news and treatment. [Monthly]

RA Insider

Beyond the basics of rheumatoid arthritis: research, news and treatment. [Monthly]

sign up


Browse the glossary by selecting a letter or by entering an arthritis-related term:

Immune system

The body’s complex biochemical system for defending itself against bacteria, viruses or other foreign invaders. Among the many components of the system are a variety of cells (such as T cells), organs (such as lymph glands) and chemicals (such as histamine and prostaglandins).

Immunosuppressive drugs

Drugs that suppress the immune system. These treatments may help curb the self-directed immune response in diseases such as rheumatoid arthritis and lupus. However, they must be used cautiously because they can also inhibit the normal immune response, leaving people who take them vulnerable to serious infection.


A response to injury or infection that involves a sequence of biochemical reactions. Inflammation can be generalized, causing fatigue, fever and pain or tenderness all over the body. It can also be localized, for example, in joints, where it causes redness, warmth, swelling and pain.

Infectious arthritis

A form of arthritis that occurs when a blood-borne infection settles in a joint or joints.


A doctor who specializes in the diagnosis, prevention of all forms of adult disease. Training for an internist requires four years of medical school, followed by a three-year residency. Internists may choose to take additional subspecialty training in particular fields, such as rheumatology, endocrinology, cardiology or gastroenterology.

Arthritis Today Magazine


Subscribe and Receive
a FREE Drug Guide

Subscribe Now

Juvenile Arthritis information & resources

see all

Just For Kids

A website for kids, tweens, and teens with arthritis

click here


Looking for a quick definition of a term?

view the glossary