If you have psoriatic arthritis and experience persistent pain and fatigue, you may need to be screened for a chronic disorder known as fibromyalgia. The two conditions often occur together and share some symptoms, but they require different treatments.

Despite their similarities, “an astute rheumatologist won’t have trouble differentiating fibromyalgia from psoriatic arthritis,” says Philip Mease, MD, a rheumatologist at Swedish Medical Center in Seattle. “We develop almost a sixth sense about it.”

Diagnosis: Psoriatic Arthritis

In addition to pain and fatigue, many people with psoriatic arthritis experience other symptoms that may differentiate the condition from fibromyalgia. These can include:

  • Psoriasis patches on the skin, or nail psoriasis
  • A family history of psoriasis
  • The swelling of a whole toe or finger, referred to as “sausage digits”
  • Tender, swollen joints

There isn’t a specific test for psoriatic arthritis. To rule out other causes of joint pain and stiffness, doctors rely on a combination of tests:

  • Blood tests that show markers for inflammation without rheumatoid antibodies
  • MRIs or ultrasounds that show inflammation consistent with enthesitis, a condition affecting the points where tendons or ligaments connect to bones
  • X-rays that show damage from early disease

Screening for Fibromyalgia

People who have psoriatic arthritis are at greater risk of developing fibromyalgia, and women are more likely to have fibromyalgia than men.

As with psoriatic arthritis, there’s no specific test for fibromyalgia.

Your doctor will ask you what symptoms you have, how severe they are, and how long you’ve had them. These symptoms may include:

  • Widespread pain
  • Cognitive problems, known as “brain fog” or “fibro fog”
  • Sleep problems, including waking feeling unrefreshed
  • Abdominal pain or bowel problems
  • Dizziness
  • Headache
  • Numbness or tingling in hands and feet
  • Restless legs
  • Frequent urination

“Sometimes people with psoriatic arthritis are on their fourth or fifth rheumatologist before a rheumatologist realizes they might have both,” Dr. Mease says. “Keep in mind that a person with psoriatic arthritis can have other forms of arthritis as well.”

Treating Fibromyalgia

If fibromyalgia goes undiagnosed, it may interfere with the treatment of psoriatic arthritis.

The concern, as Mease explains, is that "if a doctor doesn’t recognize the presence of fibromyalgia, he or she could increase the dosage of powerful drugs or switch drugs [being used to treat psoriatic arthritis] unnecessarily." Instead, what the doctor needs to do is treat the fibromyalgia.

There is no known cure for fibromyalgia, but medication and other therapies can help relieve symptoms. “The first treatment for fibromyalgia is often with a nonaddictive sleep aid, because fibromyalgia disrupts phase 4 sleep, which is the deep sleep that’s most restful and restorative,” says Marina Magrey, a bachelor of medicine and bachelor of surgery specializing in rheumatology and an associate professor at Case Western Reserve University in Cleveland.

To relieve pain associated with fibromyalgia, “we usually prescribe Cymbalta (duloxetine), Neurontin (gabapentin), or Lyrica (pregabalin),” Dr. Magrey adds. Nonsteroidal anti-inflammatory drugs (NSAIDS) and muscle relaxants may also be prescribed.

Exercise can help reduce pain and enhance quality of life for people with both psoriatic arthritis and fibromyalgia. Mease and Magrey recommend water exercises such as water walking, water aerobics, and swimming.

“It may take three weeks before exercising doesn’t hurt,” Magrey says. “But then you’re up the hill, and exercising will feel much better.”