Psoriasis is a skin disease that causes patches of itchy, red skin with a silver, scaly appearance. The lesions can occur on any part of the body, but common areas include elbows, knees, back, face, scalp, palms, and feet.

With psoriatic arthritis, people with psoriasis also have arthritis that causes pain, stiffness, and inflammation of the joints. Although the arthritis is typically mild with occasional flare-ups, in some people, it is continuous and can cause joint damage if not treated.

The signs and symptoms of psoriatic arthritis tend to vary from person to person. They can include any of the following:

• Psoriasis
• Swelling, stiffness, or pain in one or more joints
• Fatigue (i.e., frequently feeling tired or having a general lack of energy)
• ”Sausage-like” swelling of a whole finger or toe that is painful
• Changes in nails such as tiny dents, crumbling, or separation from the nail bed
• Eye inflammation that can cause pain, redness, and blurry vision
• Inflammatory bowel disease

There is no specific test for psoriatic arthritis, but physicians will evaluate the following to diagnose the disease:

• Family history of psoriasis or psoriatic arthritis
• Signs such as swollen and tender joints, psoriasis skin lesions, and changes in nails
• Blood tests to rule out other diseases with a similar presentation (e.g., rheumatoid arthritis, gout, Lyme arthritis)
• Changes in joints or the spine using imaging tests such as x-rays, magnetic resonance imaging (MRI), or ultrasound

There is no cure for psoriatic arthritis, but treatments are effective for reducing disease symptoms and their severity. The treatments selected depend on the individual’s signs and symptoms and their severity. Often different medications are tried alone or in combination until the physician finds something that works.

Treatments for milder forms of the disease:

• Over the counter analgesics and anti-inflammatory medications to treat pain and swelling
• Corticosteroid injections into affected joints

Treatments for more severe forms of the disease:

• Disease-modifying anti-rheumatic drugs (DMARDS, oral therapies that broadly suppress the immune system)

• Biologic response modifiers (i.e., therapies that target specific immune signals to reduce disease activity)

The efficacy of different supplements for improving symptoms or disease activity is unclear. There have been some pilot trials, but most of them have been limited by a small sample size, short duration, and/or lack of appropriate blinding.

The following supplements have been studied in preliminary trials for psoriatic arthritis:^[1]

• Vitamin D
• Omega-3 fatty acids
• Primrose oil
• Gamma linolenic acid
• Coenzyme Q10, vitamin E, and selenium aspartate (in combination)
• Tripterygium wilfordii (i.e., thunder god vine)
• Paeony
• Curcumin

In some people with psoriatic arthritis, eating certain foods seems to trigger symptoms,^[2] and certain diets, such as gluten free, low carbohydrate and Paleolithic are popular among patients.^[3] Fasting, vegetarian, and Mediterranean-style diets have also been evaluated in patients with psoriatic arthritis, but the overall quality of evidence is low.

Although the effect of different diet interventions is not clear, obesity is associated with significantly higher disease activity in psoriatic arthritis patients.^[4] Thus, any diet leading to weight loss may be helpful for controlling disease symptoms.

Several small studies and case-reports have tested the effect of acupuncture on psoriatic arthritis, with overall positive results. Although high quality evidence is lacking, acupuncture is conditionally recommended by the American College of Rheumatology and the National Psoriasis Foundation.^[5]

Exercise, yoga, stretching, and aqua therapy (because it tends to be easier on the joints to move around in water) are also helpful to improve overall health and to keep joints flexible.^[6] Physical and occupational therapy can also help to strengthen muscles and increase flexibility, which can protect joints from further damage.

The cause of the autoimmune activity responsible for psoriatic arthritis pathology is not well understood. Both genetic and environmental causes have been implicated.

• Genes: many people with psoriatic arthritis have relatives with the disease, and researchers have identified some of the genes involved

• Environment: stress, obesity, infection, and injury have all been implicated in triggering disease onset