"Arthritis" strictly means inflammation of the joints, but the word is used more generally for almost all joint problems. So the term inflammatory arthritis means those diseases of joints where the immune system is causing inflammation in the joint.

The most common types are rheumatoid arthritis, gout, psoriatic arthritis (associated with the skin condition psoriasis), reactive arthritis, viral or post-viral arthritis and spondylarthritis which affects the spine as well as joints. These different types of arthritis all have many features in common, so that it may be impossible to say exactly what type of arthritis it is. This is especially so at the onset of arthritis, as the early symptoms are common to all types. As a rule, any type of arthritis can affect any joint, but some patterns of affected joints are typical of particular types of arthritis.

The characteristic symptoms of inflammatory arthritis are pain and swelling of one or more joints, which can often be warmer than the other joints. Stiffness of the joints on getting up in the morning, or after sitting still for a time is very common and is sometimes the first symptom. These symptoms may begin after a minor illness such a sore throat or a cold, or may even be associated with a period of emotional stress such as a bereavement. Usually, however there is no identifiable cause.

If symptoms persist or get worse it is important to get medical advice soon. Arthritis is less likely to become severe or crippling if it is assessed and treated as soon as possible. The general assessment of arthritis includes a full physical examination (arthritis can affect other tissues such as skin and eyes), blood tests (to help measure the severity) and x-rays (to see if the joints are damaged). The blood tests may include a rheumatoid factor (RF) which is a protein present in the blood of some patients with rheumatoid arthritis, and an ESR, CRP or plasma viscosity, which can all give an indication of how active the arthritis is, and/or how effective the current treatment.