Psoriatic arthritis (PsA) is a chronic, inflammatory musculoskeletal disorder in people with psoriasis.

Patients with PsA often complain of muscle pain and weakness. There are several reasons people with psoriatic arthritis can have muscle pain and weakness.


PsA causes pain and stiffness of the joints. Patients can experience impaired mobility in the spine as well as in the peripheral joints (joints of arms and legs). This can lead to decreased physical activity and exercise.

PsA patients can often spend long periods sitting or lying in bed if their disease is not well controlled. Muscle weakness from immobility can develop over time.


Another reason for muscle weakness and pain in people with PsA may be chronic inflammation.

High levels of inflammation as measured by markers in the blood, such as C-reactive protein, have been associated with smaller muscle size.

Inflammatory proteins in the blood can stimulate the breakdown of protein in the body as well as reduce the production of protein in the muscles. This leads to muscle wasting and a decrease in skeletal muscle mass and strength.


Obesity can also contribute to inflammation.

Body fat is known to increase the production of inflammatory markers in the blood such as tumor necrosis factor (TNF), interleukin-6, and CRP.

This pro-inflammatory state is associated with the development of psoriasis and psoriatic arthritis as well as causing greater arthritis activity with damage to the muscles, cartilage, and bones.

Having obesity is more common in PsA patients than in those without PsA. Up to 45% of people with PsA have obesity.

People with obesity carry more inflammation and are less responsive to PsA medications, such as TNF blocker.

Carrying extra weight can cause worsening of PsA symptoms. Body fat increases stress on the joints and can increase musculoskeletal pain and injury.

Losing weight helps reduce inflammation, pain, stiffness, and fatigue. Weight reduction is also associated with improved response to treatment with TNF blockers by reducing inflammation.

Even after inflammation is controlled, about 20% of patients still have ongoing body pains. Some of this pain is thought to be caused by problems in pain signals from the nervous system.

Chronic low-grade or intense episodes of inflammation turn up the “volume” of nerve signals from the central nervous system, which leads to increased sensitivity to pain. People with PsA experience widespread body pain and tenderness.

In one study, there were found to be gender differences in reported pain intensity. Women exhibited a two-to-threefold increased likelihood of widespread pain in the spine and peripheral joints.

Decreased muscle mass or muscle wasting (sarcopenia) can occur as a result of aging or immobility.

Muscle wasting can also be caused by nutritional deficiencies, chronic inflammation, and reduced physical activity. PsA patients who have chronic pain and joint stiffness are less likely to engage in weight-bearing exercises and are more likely to be sedentary or even bed-bound, which can lead to muscle wasting.

Loss of lean muscle mass can lead to weakness and disability. There are a few studies that have demonstrated muscle loss from psoriatic arthritis. In one study, women with psoriatic arthritis were found to have more muscle loss more than twice as often as women without the condition.

In another study, using MRI scans, hand muscle volume was found to be significantly decreased with age for people with psoriatic arthritis. The decrease in hand muscle volume was twice that in men than women among PsA patients.

Psoriatic arthritis is a musculoskeletal disease that can involve the joints, spine, or ligaments/tendons.

The musculoskeletal pain can present in four ways:

  • arthritis of the spine (axial arthritis)
  • arthritis of the joints of the arms and legs (peripheral arthritis)
  • swollen fingers or toes (dactylitis)
  • inflammation of the site where a ligament or tendon inserts into a bone (enthesitis) — these can include the Achilles tendon of the ankle, the elbows, heels, hips, knees, or shoulders

PsA can cause damage to the bones over time, including erosions. Over 50% of patients develop joint damage and decreased functionality within 2 years of diagnosis.

Inflammatory back pain from psoriatic arthritis has the following characteristics:

  • It’s worse with inactivity.
  • It’s worse when rising in the morning, or it wakes you up in the middle of the night.
  • It improves with activity, worse with rest.
  • It occurs gradually.
  • It’s chronic (lasting more than 3 months).

Once the inflammation from the psoriatic arthritis is under control, exercise can be introduced.

Physical activity has been shown to improve muscle strength and pain in PsA patients.

The American College of Rheumatology guidelines for the treatment of PsA recommend low impact exercises such as swimming, walking, tai chi, yoga, and Pilates to help stretch your muscles and prevent stiffness.

High impact exercises may be considered if there’s no contraindication. You may want to discuss this with your doctor.

One study showed resistant exercises using machine leg extension and a triceps machine as well as free weights reduced pain, improved daily function, and improved muscle strength.

Range of motion and stretching exercises may help protect your muscles.

Your doctor may refer you to physical therapy or occupational therapy. Massage therapy and acupuncture may be helpful in some people, but the effectiveness is not conclusive.

Applying heat alternating with ice to the muscles may be soothing.

Fibromyalgia is a chronic pain condition that can coexist with rheumatic diseases including PsA. Symptoms of fibromyalgia include:

  • widespread musculoskeletal pain
  • fatigue and problems with sleep
  • “brain fog” with problems paying attention and concentrating
  • depression or anxiety
  • burning, numbness, or tingling sensation in the arms and legs
  • migraine attacks, headaches, or pelvic pain

In one study, almost 40% of participants with PsA also had fibromyalgia. Pain, tenderness, and fatigue were found to be increased in people with combined PsA and fibromyalgia, as compared to the PsA-only group and the fibromyalgia-only group.

Fibromyalgia is a clinical diagnosis. There’s no diagnostic blood test or x-ray. Your doctor may want to do additional tests to rule out other conditions that are mimickers of fibromyalgia.

Early treatment with medications can keep the PsA inflammation under good control and reduce pain, muscle pain, and stiffness.

These medications include:

  • nonsteroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation — they’re available over the counter or by prescription and include ibuprofen, naproxen, diclofenac, and meloxicam
  • conventional disease-modifying antirheumatic drugs (DMARDs) such as methotrexate, leflunomide, and sulfasalazine
  • biologics, which target cytokines or inflammatory proteins such as TNF IL-17, IL-12/23, IL-23, and CTLA4-Ig
  • targeted synthetic DMARDs such as tofacintinib (Xeljanz)
  • the oral medication apremilast (Otezla)
  • massage and acupuncture, though these interventions have little scientific backing and may offer temporary relief

If you’re diagnosed with fibromyalgia and PsA, treatment for fibromyalgia includes medications such as anticonvulsants, antidepressants, muscle relaxants, and sleep aides.

Lifestyle changes for fibromyalgia include good sleep hygiene, low impact aerobic exercise, stress reduction through meditation, journaling, tai chi, yoga, and cognitive behavioral therapy.

A healthy lifestyle with good nutrition and physical activity is important for managing your psoriatic arthritis muscle pain.

It’s also important to make sure there is adequate protein intake to reduce muscle loss. The recommended dietary allowance for protein intake in most adults is 0.8 g per kg of body weight per day.

In people who are overweight, the emphasis should be on reducing calories with the goal of working toward a healthier body weight.

A plant-based, Mediterranean diet is recommended by the medical board of the National Psoriasis Foundation for both PsA and psoriasis.

Make sure your diet includes:

  • whole grains (quinoa, brown rice, whole grain bread)
  • extra virgin olive oil as the main cooking oil
  • low sugar fruits such as berries, apples, and pears (at least three servings daily)
  • fish or seafood particularly fatty fish such as wild salmon, mackerel, and sardines
  • tree nuts and seeds, such as almonds and walnuts, which are high in omega-3 (at least three times weekly)
  • legumes such as beans and lentils (at least three servings weekly)
  • at least two servings of vegetables daily
  • very little or no sugar and white flour products

Dr. Margaret Li is an ABMS board certified physician with experience in internal medicine and rheumatology. She is a practicing physician at NYU-Langone Medical Center in New York City. She completed a 2-year fellowship in integrative medicine at the University of Arizona and has a special interest in treating the whole person through mind-body medicine as well as nutrition and lifestyle changes.