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Similar diseases

Although osteoarthritis is the most common rheumatic disease, there are a number of other rheumatic diseases that share similar symptoms.

A photo of a hand with reumatism with red painted nails positioned on top of a photography book.

Joint pain can have several causes and is not necessarily a sign of osteoarthritis (OA). OA may be the most common rheumatic disease, but it is not the only disease that causes symptoms such as pain and stiffness of the joints. Other causes of joint pain include inflammation of the bones, muscles, joints, and tendons or in the tissue surrounding the organs in your musculoskeletal system (locomotor system).

As many rheumatic diseases share a number of the same symptoms, it is important to receive the correct diagnosis from your healthcare provider to start the right form of treatment.

Rheumatoid arthritis (RA)

Rheumatoid arthritis is the most common inflammatory form of arthritides. When a joint is affected by RA, the synovium becomes inflamed, often causing joint swelling, pain, and stiffness. The disease mainly affects the small joints in the hands and feet but may sometimes affect other parts of the body including vital organs. Rheumatoid arthritis is an autoimmune disease, meaning that the immune system attacks the body by mistake causing in this case, inflammation in the affected body part. Most commonly, the disease attacks several joints at the same time.

Smoking increases the risk of developing rheumatoid arthritis, yet genes are the most significant risk factors for RA. It is also 2-3 times more common for women to develop RA than men.


Gout is an inflammatory rheumatic disease that causes episodes of sudden severe joint pain and swelling of the joint. An episode of severe sudden pain in the joint is known as a "gout attack". Gout tends to affect the foot, especially the big toe. Other joints in the body may also develop gout, although this is a lot less common.

Gout occurs when there is too much uric acid in the blood. The body produces uric acid when it breaks down purine, an organic compound found in food. Normally, uric acid is excreted by our kidneys, but if the body produces too much uric acid or if our kidneys are unable to excrete enough uric acid, small crystals start to form in our joints, creating inflammation. Therefore, if you suffer from gout, it may be a good idea to avoid alcohol and foods that contain high amounts of purine (e.g., bacon, mussels, sardines, veal) to relieve symptoms.


Pseudogout is similar to gout in the sense that in both disease states, crystals form in the joints creating sudden joint pain. However, unlike gout, pseudogout occurs when calcium pyrophosphate crystals form in the joints. It is often the wrist and the knee joints that are affected by the disease. The most common symptoms of pseudogout are joint pain and swelling of the joint, but it is not uncommon to experience symptoms such as joint stiffness and fatigue. Pseudogout is not as common as gout and mainly affects women over the age of 65.

Psoriatic arthritis

About 30% of all people who suffer from the skin disease psoriasis develop psoriatic arthritis. Psoriatic arthritis is an inflammatory rheumatic disease that mainly affects the small joints in the hands and feet. People with psoriatic arthritis usually get red scaly patches on the skin as well as joint pain and stiffness. Joint pain sometimes starts before the red patches appear, which makes the disease difficult to diagnose as the pain is similar to that of other rheumatic diseases. Typical for psoriatic arthritis is that it attacks one single joint. It is unusual for several joints to be affected at the same time. Psoriatic arthritis usually affects people between the ages of 30-55.

Systemic lupus erythematosus (SLE)

Systemic lupus erythematosus (SLE) is an autoimmune disease, primarily affecting the joints and skin. In some cases, SLE also attacks the organs in the body such as the heart, blood, and kidneys. A common sign of SLE is the development of a malar rash (also known as a “butterfly” rash) in the face. The rash covers the bridge of the nose and the cheeks, resembling the shape of a butterfly. Other symptoms of SLE include hair loss (alopecia), sensitivity to sunlight, and mouth ulcers. When SLE attacks the joints, severe joint pain can occur as a result of the joints becoming inflamed. 90% of those affected by SLE are women and the disease tends to affect younger women under the age of 45.


Fibromyalgia is a disease that differs from many other rheumatic diseases, as it is not considered inflammatory. The disease is a so-called soft tissue rheumatic disorder, characterized by pain or achiness in the soft tissues of the body (i.a. muscles, ligaments, blood vessels, nerves). Around 80–90% of all fibromyalgia sufferers are women. The pain can be generalized, meaning that it can be present in several parts of the body at the same time. It may also move throughout the body, depending on the day. The intensity of the pain tends to vary. Morning stiffness in the muscles can occur, but the most common symptoms of the disease are body aches and skin sensitivity. For a long time, the disease was misunderstood and not recognized as it has no outwardly visible signs. Today, fibromyalgia is a recognized clinical disease although the cause of the disease is still relatively unknown. Doctors and researchers believe that those suffering from fibromyalgia have disturbances in how the central nervous system processes pain.