Psoriasis and rheumatoid arthritis both are autoimmune diseases that cause inflammation. While people with psoriasis are more likely to develop psoriatic arthritis than rheumatoid arthritis, you can develop both conditions.

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Psoriasis is an autoimmune condition that primarily affects the skin, while rheumatoid arthritis (RA) is an autoimmune condition that primarily affects the joints. Both conditions involve the body’s immune system, and both can cause inflammation in the body, but they are distinct from one another.

It is possible to have both psoriasis and RA. In fact, autoimmune diseases often co-occur. But people with psoriasis are actually at higher risk of developing a type of arthritis called psoriatic arthritis. Psoriatic arthritis affects the joints, just like rheumatoid arthritis, but the symptoms are slightly different.

This article will examine links between psoriasis and rheumatoid arthritis, whether they can occur together, the connection between psoriatic arthritis and rheumatoid arthritis, and how each condition is diagnosed and treated.

Psoriasis and RA are autoimmune-related diseases, which develop when your immune system mistakenly attacks your healthy cells and tissues. The immune system is supposed to protect the body from harmful foreign invaders, like germs, but it can make mistakes.

Some autoimmune diseases follow similar symptom patterns. Conditions like RA tend to flare up and then go into a period of remission, where symptoms disappear for a time. These remissions can last for days, months, or years.

Psoriasis and psoriatic arthritis follow this same pattern, which is one reason doctors have long considered them autoimmune diseases. However, evolving research suggests there may be more to it: psoriasis and psoriatic arthritis may be autoinflammatory conditions, which are very similar to autoimmune diseases.

Inflammation is a common symptom of autoimmune conditions. With psoriasis, inflammation affects the skin. With RA, inflammation affects the joints and leads to swelling and pain. With psoriatic arthritis, which affects many people with psoriasis, joint tissues also become inflamed.

It is possible to get both psoriasis and RA. Psoriasis and RA are autoimmune conditions. Researchers don’t know exactly what causes autoimmune diseases, but they suspect it’s a combination of several factors.

Factors that may lead to an autoimmune disease include:

  • genetics
  • viral or bacterial infections
  • environmental triggers
  • immune system abnormalities
  • stress
  • an imbalance of the microbiome
  • tissue injuries

Certain medications used to treat RA, known as biologics, can also trigger psoriasis and other autoimmune conditions in people who are genetically predisposed.

Some autoimmune diseases co-occur with other autoimmune diseases. For example, type 1 diabetes often co-occurs with autoimmune thyroid conditions.

There is also a rare condition known as multiple autoimmune syndrome, which occurs when someone has three or more autoimmune diseases. With this condition, one of the autoimmune diseases is always skin-related, like psoriasis.

Psoriatic arthritis

While there is a chance that you could develop both psoriasis and RA, it is more common for people with psoriasis to develop psoriatic arthritis.

Psoriasis is a disease that manifests in several different ways, the most common being plaque psoriasis, which causes thick, scaly patches to form on the surface of the skin. Psoriatic arthritis is a disease that manifests in the joints, causing swelling and pain.

About 33% of people with psoriasis develop psoriatic arthritis.

If you have psoriasis and you’re experiencing joint pain, you’re probably wondering what’s causing it. Several different types of arthritis could be the culprit.

RA typically occurs symmetrically in the body, often affecting smaller joints such as the fingers, wrists, ankles, and elbows. This means that if you have pain in one wrist, you’ll have pain in the other wrist too.

Psoriatic arthritis is more likely to affect a joint on one side but not the other.

Other symptoms of psoriatic arthritis include:

Symptoms of RA include:

  • mild to moderate inflammation in a few joints
  • pain that affects more joints over time
  • pain that flares up and then resolves for periods of time

To diagnose RA, a doctor will look at your complete medical history and conduct a physical exam. They will ask how your symptoms are affecting your ability to move or engage in different activities. They may ask about limitations that are affecting your work, hobbies, or day-to-day responsibilities, like household chores.

A doctor may order bloodwork and imaging like X-rays, MRIs, or ultrasounds.

There is no single test for RA, but bloodwork can reveal the presence of autoantibodies and inflammatory markers that are common in people with autoimmune conditions like RA.

With bloodwork, doctors can test for:

  • rheumatoid factor
  • anti-cyclic citrullinated peptide antibody
  • complete blood count
  • erythrocyte sedimentation rate
  • C-reactive protein

Imaging tests may include:

Some of the treatments for psoriasis and RA are quite similar. For example, medications that help reduce immune system activity can help prevent psoriasis and RA flare-ups. Medications that help reduce inflammation can provide pain relief during a flare.

Medications used to treat both conditions include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs help reduce inflammation and treat painful skin lesions and joints.
  • Disease-modifying antirheumatic drugs (DMARDs): DMARDs like methotrexate work by suppressing your immune response. They can help reduce the likelihood of flare-ups.
  • Biologics: Biologic DMARDs work to interrupt your body’s inflammatory process. These targeted medications can reduce the likelihood of psoriasis and RA flares, and they have fewer side effects than traditional DMARDs.

There are additional treatments for psoriasis that you may benefit from, depending on the severity of your symptoms. Treatments may include creams and ointments that you apply to the skin and ultraviolet light therapy.

Psoriasis, psoriatic arthritis, and rheumatoid arthritis are all autoimmune conditions that cause inflammation in the body. These conditions can occur at the same time, but people with psoriasis have a higher risk of developing psoriatic arthritis than rheumatoid arthritis. These conditions share many of the same risk factors and treatments.