Osteoarthritis
Osteoarthritis is a joint disease in which tissues in the joint break down over time. It is not the same process as autoimmune inflammatory arthritis.
Read NIAMS osteoarthritis informationUNDERSTAND THE LANDSCAPE
Arthritis is not one condition.
Arthritis describes many conditions that affect joints and, in some cases, other parts of the body. Causes, evaluations, and treatments differ. This page is a map—not a diagnosis.
Updated August 3, 2026
One distinction matters immediately: not every kind of arthritis is autoimmune, and not every painful joint is arthritis.
Autoimmune and inflammatory arthritis
Conditions such as rheumatoid arthritis, psoriatic arthritis, and some spondyloarthritis conditions involve immune-system-driven inflammation. They can differ in pattern and in whether other organs or tissues are affected.
Read NIAMS rheumatoid arthritis informationCrystal arthritis
Gout is a type of inflammatory arthritis associated with uric-acid crystals in joints. A website cannot confirm that a sudden painful joint is gout or safely rule out infection.
Read NIAMS gout informationArthritis related to infection
Infections can directly affect a joint, and some infections can trigger reactive arthritis. A rapidly painful, swollen, hot, or difficult-to-move joint—especially with fever or feeling very unwell—needs prompt professional attention.
Read the fixed safety pageJuvenile arthritis
Arthritis can affect children. Pediatric evaluation and age-appropriate specialty care are important; adult-oriented tools are not a substitute.
Read NIAMS juvenile arthritis informationOther rheumatic and musculoskeletal conditions
Joint-area pain can also relate to tendons, bursae, muscles, injuries, nerves, infection, or other conditions. That is why the site routes by purpose instead of guessing from symptoms.
Why joint pain is not always arthritisYOUR NEXT STEP
Turn information into a better appointment.
Use the question builder to choose practical topics and create a private list for your next conversation.
SOURCE DESK
Authoritative starting points
These organizations publish the original guidance used to shape this page. External resources may change; confirm current information directly with the source and your licensed care team.
- NIAMS — Arthritis overview and types U.S. National Institutes of Health overview of arthritis and major categories.
- NIAMS — Osteoarthritis Federal health information about osteoarthritis.
- NIAMS — Rheumatoid arthritis Federal health information about rheumatoid arthritis.
- NIAMS — Arthritis and rheumatic diseases NIH directory covering arthritis and related rheumatic diseases.