The Link Between Psoriasis and Psoriatic Arthritis

If you have psoriasis and develop joint pain, your healthcare provider may have you checked for psoriatic arthritis (PsA). Occasionally, people will have PsA and develop psoriasis later on. Why is there a connection between these two conditions? Are people with either psoriasis or psoriatic arthritis more likely to develop both conditions?

The Connection

Abnormal immune system responses are at the core of both PsA and psoriasis. With psoriasis, the immune system misfires and causes skin cells to grow too quickly. The accumulation of skin cells causes layers of red, itchy plaques. With PsA, the immune system inflames joints and connective tissues, causing swelling and pain in those areas.

Sometimes, however, arthritis symptoms appear months or even years before skin problems. In those instances, it is harder to make a dual diagnosis or even to diagnose PsA correctly. 

There is a genetic component to both PsA and psoriasis, though scientists aren’t sure what genes are responsible for causing these conditions.

Of course, having specific genes for PsA and psoriasis does not mean you will eventually develop one or both conditions. To develop these conditions, you may be exposed to certain triggers in addition to having specific genes. However, being exposed to these triggers in addition to genes still does not guarantee PsA and/or psoriasis. Triggers and genes heighten your risk.

Possible triggers include:

• Stress
• Infections
• Skin injuries
• Tattoos and piercings
• Certain medications
• Cold weather
• Alcohol and/or tobacco use

Triggers are also responsible for causing flare-ups (periods during which disease symptoms are active). Triggers for PsA and psoriasis will vary the longer you have had one or both conditions and also vary from person to person.

Prevalence

According to the National Psoriasis Foundation, up to 30% of people with psoriasis also have psoriatic arthritis. However, one meta-analysis reported in the Journal of the American Academy of Dermatology finds the incidence of PsA in patients with psoriasis may actually be lower—around 20%.

The meta-analysis identified 266 studies of patients with psoriasis. Of the 976,408 people in those studies, 19.7% also had PsA. Some prevalence differences did exist among the studies, but the researchers suggest these might be related to genetic and environmental factors typical in the development of autoimmune diseases.

Differences could also be related to different methods of classifying data.  

Differences

Inflammation in both PsA and psoriasis starts on the inside. With PsA, the process of inflammation is invisible. With psoriasis, internal inflammation makes its way outside to the skin. While the underlying processes of psoriasis and PsA are similar, there are differences between the two conditions.

Location

Often, there is no clear connection between the location of skin plaques and affected joints. For example, having skin lesions on your elbow does not mean you will have pain, swelling, and problems bending or moving that elbow. Or, you can have swollen, inflamed toes, but no plaques on your feet.

However, certain psoriasis skin distributions are associated with psoriatic arthritis. For example, scalp, umbilicus, and nail involvement are associated with inflammatory arthritis.

Harm

Psoriasis does not usually cause lasting harm, such as scars, to your skin. However, PsA can severely damage your joints and leave them deformed, and even cause disability, especially if left untreated or under-treated.

It is also important to continue taking your medications for as long as your healthcare provider tells you to.

Progression

The most common type of psoriasis is plaque psoriasis, which affects up to 90% of people with psoriasis. Skin plaques in plaque psoriasis tend to come and go. 

PsA, on the other hand, is progressive. The inflammation associated with it can lead to long-term damage, and symptoms could potentially get worse with time. In addition, people with PsA have a higher risk for other diseases, including heart disease, depression, and diabetes. 

Treatment

Aggressive treatment for PsA should start as soon as joint symptoms develop, because PsA can be quite debilitating. Your healthcare provider will create a treatment plan based on the severity of both psoriasis and PsA and how you respond to treatment. 

There are two common types of medications that treat both skin and joint symptoms: disease modifying anti-rheumatic drugs (DMARDs) and biologics. In addition, other novel drugs have recently become available.

DMARDs, such as Arava (leflunomide), Trexall (methotrexate), and Azulfidine (sulfasalazine) suppress the immune system to slow down inflammatory processes. If your symptoms are severe, especially with PsA, your healthcare provider may recommend two DMARDs.

Biologic drugs are made from living cells. They treat PsA and psoriasis by targeting the parts of the immune system where inflammation occurs. These biologics, which include Stelara (ustekinumab), TNFi (etanercept, humira), IL-17i (secukinubab), and IL23i (guselkumab), have been helpful in treating both symptoms of psoriasis and PsA. 

Additional new medications targeting different pathways than DMARDs or biologics include apremilast (Otezla) and tofacitinib (Xeljanz).

If your PsA is severe, your healthcare provider will prescribe a biologic, in addition to one or two DMARDs.

Other treatments will focus on one condition or the other. For example, your healthcare provider may recommend topical medicines to treat skin symptoms and nonsteroidal anti-inflammatory drugs, such as Advil (ibuprofen), to ease joint inflammation and pain. 

A Word From Verywell

If you have psoriasis, there is a likelihood that you may develop psoriatic arthritis. Keep an eye out for symptoms of joint pain and stiffness. If you start to develop symptoms, talk to your healthcare provider. He or she may refer you to a rheumatologist, who will determine whether PsA or another arthritic condition is involved. 

If you are diagnosed with PsA, treatment should start as early to possible to reduce the potential for joint damage and disability. Proper treatment will also preserve your quality of life and reduce any risk for life-threatening complications.