Most people think of psoriasis as a skin condition marked by red, flaky, scaly patches of skin, but many people don't know that there is often another side to psoriasis: arthritis.
About 30 percent of people with psoriasis end up with psoriatic arthritis, according to the National Psoriatic Arthritis Foundation. The inflammatory arthritis condition affects a person's joints, tendons, and ligaments. Psoriasis and psoriatic arthritis are both autoimmune conditions, so the fact that there's a link between them—or that skin inflammation could trigger joint inflammation—makes sense.
9-Symptoms-of-Psoriatic-Arthritis-AdobeStock_216306900-2 tells Health. "85% of patients will have skin disease before they develop joint disease."
If you think you're in that remaining 15 percent, you're probably wondering what the most common symptoms of psoriatic arthritis are. We talked to rheumatologists about the key signs to look out for and here's what they said.
RELATED: Psoriatic Arthritis Vs. Rheumatoid Arthritis: How the 2 Conditions Differ, According to Experts
Rashes and redness
Because psoriatic arthritis starts as a chronic inflammatory skin disease, it can also be identified with the onset of rashes. The traditional psoriatic skin rash is red, raised, and scaly; these are called plaques.
The plaques may be painful or itchy, and they can appear on your elbows, knees, scalp, hands, feet, and lower back (among other places). Plaque psoriasis is the most common type of rash, but there are others, including smooth rashes that pop up in skin folds and rashes with blisters or pustules.
Swelling
It's common for the tissue surrounding your joints to become inflamed with psoriatic arthritis, causing those joints to swell. This happens frequently in fingers and toes (which is where the unfortunate descriptor "sausage fingers" came from). The joints may also appear red and feel warm to the touch.
Joint pain
People with psoriatic arthritis are prone to joint pain because of increased swelling, John Gallucci Jr., DPT, Doctor of Physical Therapy and CEO of JAG-ONE Physical Therapy tells Health. "You'll notice it primarily in your fingers and toes, or feel stiffness or tightness in your ankles, shoulders, and back," he says.
Unlike other kinds of arthritis, psoriatic arthritis may be symmetrical or asymmetrical, meaning you might experience "matching" joint pain on both sides of your body, or joint pain only in one joint of a traditional "pair" (like your knees, for example). Unfortunately, the pain can also spread and worsen over time, especially if left untreated.
Stiffness
People with psoriatic arthritis often experience joint stiffness, which then affects their overall range of motion, says Dr. Gallucci. This is common in the lower extremity joints, the hands, and the back. The less you move because of joint stiffness, however, the more limited your range of motion will become, which is why it's so important to maintain even a basic exercise routine when you have arthritis.
RELATED: The 6 Best Exercises for Arthritis, According to Experts
Fatigue
Living with psoriatic arthritis is exhausting—literally. "Patients are not only trying to move through their days with pain but are also not sleeping well at night because of that pain," says Dr. Gallucci, who notes that serious fatigue goes hand-in-hand with psoriatic arthritis and can become debilitating.
Joint disability
To understand what's happening to your joints, you need to know about cytokines. Cytokines are proteins that play a role in the regulation of your immune response, but for people with autoimmune conditions like arthritis, cytokines can flood otherwise healthy tissue, causing inflammation and pain but also—more seriously—bone damage.
"Cytokines attack the joints, which can make the joints feel spongy, can erode the bones, and even cause joint fusion," says Dr. Greer.
Dr. Gallucci mentions bone erosion as well, noting that the bone can deviate to a point where it causes mechanical issues and incongruity between joints, affecting your ability to bear weight on your joints without an assistive device.
Fingernail defects
Don't overlook the fact that fingernails and toenails are commonly affected by systemic skin conditions, and psoriatic arthritis is no exception. Dr. Greer says nails may become thickened, crumbly, or more prone to fungal infections, may show signs of pitting, and may even separate from the nailbed.
If your doctor isn't sure if your nail problems are related to psoriatic arthritis or not, Dr. Greer says a nail biopsy can be performed; in some cases, an especially "astute" dermatologist may pick up on the possible connection, he adds.
RELATED: This Man's Pitted Nails Turned Out to Be a Chronic Skin Condition
Eye Inflammation
Lest you think there's any part of your body safe from the effects of psoriatic arthritis, there's also a chance of uveitis, an inflammation of the middle layer of eye tissue. Your eye or eyes may become red and irritated, and you may have pain or notice changes in your vision like blurriness.
Dr. Greer notes that eye inflammation is common with all the spondyloarthritis diseases, including psoriatic arthritis, because cytokines can affect the healthy tissues of your eyes; you may also have other inflammatory conditions as well, such as inflammatory bowel disease (IBD) or Crohn's disease.
Inflammatory Back Pain
Everyone over the age of 30 has some back pain, right? So how can you tell if yours is a warning sign of psoriatic arthritis?
"Back pain from psoriatic arthritis gets worse with rest and better with activity, which is the opposite of 95 percent of [the other causes of] back pain," says Dr. Greer.
This is because you're dealing with more than a pulled muscle or overuse injury, aka mechanical back pain. Per the Arthritis Foundation, inflammatory back pain develops when there are abnormalities on and around your vertebrae, which can actually cause the joints of your spine to fuse together. That's not only painful, but can limit your range of motion (which, again, will only worsen with less movement).
Enthesitis
Psoriatic arthritis is known for causing joint pain and inflammation, but it can also affect the place where a tendon connects to a bone (called an enthesis). When an enthesis becomes inflamed, it's known as enthesitis—and it happens to about one in three people with psoriatic arthritis. Patients may have tendonitis for a long time without realizing it's actually psoriatic arthritis," explains Dr. Greer, "and in some cases, it may even be the first symptom."
Common spots for enthesitis to occur are the ankles, heels, and bottoms of feet, though it can also happen in your knees, elbows, shoulders, hips, and any other joint typically affected by arthritis.
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