How Psoriatic Arthritis Causes Back Pain — and What to Do About It

Psoriatic arthritis is known for causing peripheral arthritis, which is pain in the joints of the hands, wrists, knees, and ankles. But the condition can also affect the spine and pelvis, causing back pain. In fact, back pain is very common in people with psoriatic arthritis, says John Davis III, MD, a clinical rheumatologist who specializes in psoriatic arthritis and axial spondyloarthritis at Mayo Clinic in Rochester, Minnesota.

Psoriatic arthritis is a chronic inflammatory condition that can cause pain and stiffness in any joint in the body or anywhere the ligaments and tendons connect to bone. When psoriatic arthritis specifically affects the joints in the vertebrae of the spine, it’s known as spondylitis or axial spondyloarthritis. Sacroiliitis is when psoriatic arthritis affects the joints between the pelvis and spine, known as the sacroiliac joints.

“Spondylitis leads to inflammation around the ligaments that hold the spine together,” causing back pain, says Rajat Bhatt, MD, a rheumatologist at Prime Rheumatology in Pearland, Texas. The condition causes abnormal bone growth and erosion between the vertebrae that may cause them to merge, which can decrease range of motion.

But back pain can have other causes in people with psoriatic arthritis. “[If] patients are overweight or obese and sedentary, mechanical back pain [can] coexist with psoriatic arthritis,” Dr. Bhatt explains.

According to Davis, when psoriatic arthritis affects the spine, it can cause:

• Back pain that gets worse with rest and better when moving
• Back stiffness in the morning that lasts at least 30 minutes
• Inflammatory pain in the hips and butt (around the sacroiliac joints)
• Reduced range of motion

If your back is bothering you, it’s important to check in with your doctor to get to the root cause.

Ultimately, imaging of your back will help your doctor determine whether you have axial psoriatic arthritis or ankylosing spondylitis. “Although there is overlap, there are some subtle differences in the appearances of X-ray changes in both the sacroiliac joints and the spine,” Davis explains.

Another common cause of discomfort is mechanical back pain, which is linked to an injury. If you have obesity, the pain may be caused by added weight on your spine. Unlike spondylitis, which is usually better when you move and worse with rest, mechanical back pain is worse when you move and better with rest, according to both Davis and Bhatt. Mechanical back pain also tends to cause brief back stiffness when you wake up, whereas spondylitis causes lingering morning stiffness, Davis adds.

That said, it’s easy to mistake symptoms of one condition for the other. “What appears to be mechanical pain could be inflammatory pain, and what appears to be inflammatory pain could be mechanical pain,” says Bhatt.

People who have psoriatic arthritis may also have back pain linked to a number of other causes, says Davis, including:

• Osteoarthritis of the spine, also known as degenerative joint disease of the spine
• Spinal stenosis, or the narrowing of spaces in your spine that triggers nerve pain
• Fibromyalgia, or widespread musculoskeletal pain that’s thought to happen when the brain processes pain differently than normal
• Central sensitization, a condition where the central nervous system amplifies the sensation of pain

“It’s a very complex topic, so it’s best to ask a doctor,” Bhatt emphasizes. “There are certain tests your doctor can run to confirm the right diagnosis.”

• Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen
• Disease-modifying antirheumatic drugs (DMARDs), such as leflunomide, methotrexate, and sulfasalazine
• Biologic drugs, including interleukin (IL) inhibitors IL-12, IL-17, and IL-23 (such as guselkumab, ixekizumab, secukinumab, and ustekinumab), as well as tumor necrosis factor alpha (TNF-alpha) inhibitors (such as adalimumab, certolizumab, etanercept, golimumab, and infliximab)
• Janus kinase (JAK) inhibitors, such as tofacitinib and upadacitinib
• Corticosteroid injections

You’ll likely be on at least one of these treatments long term, because odds are good that it will work. “Most patients improve, and we see fairly high rates of remission,” says Davis.

• Back pain is common in psoriatic arthritis, which can cause inflammation in the spine (spondylitis or axial spondyloarthritis) or pelvis (sacroiliitis).
• Inflammatory back pain from psoriatic arthritis typically worsens with periods of rest or inactivity, such as in the morning, and tends to improve with movement.
• This type of pain often goes undiagnosed, but identifying the cause and treating it promptly can help ease symptoms and prevent the progression of the condition.

Additional reporting by Nina Wasserman.