Inflammatory arthritis describes conditions characterized by pain, swelling, tenderness and warmth in the joints, as well as morning stiffness that lasts for more than an hour. The most common forms are rheumatoid arthritis (RA), psoriatic arthritis (PsA), systemic lupus erythematosus (SLE, lupus), gout and ankylosing spondylitis (AS). In these diseases, the immune system doesn’t work properly and releases inflammatory chemicals. The resulting inflammation attacks joint tissues and can cause joint swelling, increased joint fluid, cartilage and bone damage, and muscle loss. Nerves in the joints are also activated, causing pain. The inflammatory chemicals may directly activate other nerves of the body and lead to pain as well.