Psoriatic Arthritis vs. Reactive Arthritis: What Are the Differences?

Psoriatic arthritis (PsA) is an autoimmune disease that affects the joints and skin. In the joints, it causes pain, stiffness, and swelling, which can lead to long-term damage and disability.

PsA can also cause skin symptoms and is commonly linked to the inflammatory condition psoriasis, which is known for causing red, silvery plaques from the overproduction of skin cells. PsA is a commonly misdiagnosed condition.

According to a 2018 study reported in the Annals of the Rheumatic Diseases, 96% of people who were eventually diagnosed with PsA received at least one misdiagnosis before their PsA diagnosis. For about 30% of people with PsA, a diagnosis took five or more years.

Diagnostic delays can lead to irreversible joint damage, which is why it is vital to get a diagnosis early and treat the condition quickly and aggressively. Reactive arthritis is one condition that is sometimes mistaken for PsA.

Reactive arthritis is a type of spondyloarthritis. "Spondyloarthritis" is an umbrella term for inflammatory diseases that affect the back, pelvis, neck, and other large joints. PsA is also a type of spondyloarthritis.

What makes reactive arthritis different from PsA is that it is triggered by a bacterial infection and is not an autoimmune disease­—a condition in which the immune system mistakenly attacks healthy tissues.

This article will discuss the differences between PsA and reactive arthritis, including symptoms, causes, and treatment.

Symptoms

Psoriatic arthritis is an inflammatory form of arthritis that attacks joints all over the body. PsA also affects the fingertips and spine and can range from mild to severe. The condition is known for flare-ups, which are periods of high disease activity, including worsening symptoms, and remission, times in which the disease is mild or there are no symptoms.

PsA often affects people with psoriasis, and most people will have psoriasis for many years before they have symptoms of PsA. It is much rarer, but for some people, skin symptoms appear after PsA or at the same time.

Reactive arthritis is triggered by different types of bacteria, including Campylobacter, Chlamydia, Salmonella, Shigella, or Yersinia. These types of bacteria are either sexually transmitted or ingested from eating contaminated foods.

These bacteria are very common, and most people who are exposed to them do not develop reactive arthritis. However, some people are genetically susceptible to becoming infected when the bacteria cause the immune system to react and lead to symptoms.

Both PsA and reactive arthritis are associated with inflammatory back pain, which typically has a prolonged period (greater than 45 minutes) of morning stiffness.

Psoriatic Arthritis

PsA affects between 0.06% and 0.25% of American adults, many of whom also have psoriasis. According to the National Psoriasis Foundation, PsA appears slowly, with mild symptoms that can develop very quickly and become severe.

Common symptoms of PsA include:

• Chronic fatigue
• Dactylitis, a condition that causes the fingers and toes to become so
  swollen they may resemble sausages
• Joint stiffness, pain, swelling, and tenderness, and reduced range of motion in affected joints
• Morning stiffness of joints
• Skin lesions caused plaques
• Enthesitis, causing tenderness, pain, and swelling of the tendons, the strong, flexible tissues that connect muscle to bone 
  
• Nail changes, including nail pitting and nail bed separation
• Uveitis, which is redness and pain in the eyes
• Back and sacroiliac (SI) joint pain (the SI joints connect the sacrum at the base of the spine with the hip bone)
  

Reactive Arthritis

Reactive arthritis can appear similar to PsA. It causes some similar symptoms to PsA, including asymmetric joint pain (affecting joints on one side of the body), back pain, enthesitis, and dactylitis. Reactive arthritis can also cause eye inflammation.

Initial symptoms of reactive arthritis are painful urination and discharge from the penis if the urethra (the tube that allows urine to pass out of the body) is inflamed. Diarrhea can occur if the intestines are infected. Arthritis symptoms will follow eye and urinary symptoms and can affect the fingers, toes, hips, ankles, and knees.

Additional symptoms may include:

• Mouth ulcers
• Eye symptoms, including conjunctivitis (pink eye) and sometimes, iritis—inflammation of the eye
• Keratoderma blennorrhagica (patches of scaly skin on the palms, soles, trunk, or the scalp)
• Back and sacroiliac (SI) joint pain
• Enthesitis
• Inflammation of the prostate gland or cervix
• Dactylitis

Causes

The underlying causes of PsA and reactive arthritis are different. They do, however, share a genetic association—a genetic marker called HLA-B27.

Psoriatic Arthritis

Researchers believe that PsA is caused by a combination of factors, including genes and triggers like infections, stress, and physical trauma. The people with the highest risk for the condition are people who already have psoriasis.

A family history of PsA can increase your risk for PsA, and a child whose parent has PsA or psoriasis has a greater risk for developing PsA. Up to 40% of people with PsA have at least one relative with the condition or who has psoriasis.

Researchers have also identified gene changes that may contribute to the risk of PsA.  Many of these belong to a family of genes called the human leukocyte antigen (HLA) complex that helps the immune system distinguish healthy proteins from proteins made by foreign invaders.

Variations of HLA genes, including HLA-B27, are believed to affect the development of PsA and contribute to PsA type, severity, and progression. 

Additional risk factors for PsA are:

• Smoking: Researchers are unsure how exactly smoking might cause PsA. What they do know is that it is linked to oxidative stress, which can promote chronic inflammation.
• Overconsumption of alcohol: The research on alcohol consumption and PsA is mixed, but researchers think alcohol might be a risk factor.
• Obesity: Many studies find a higher prevalence of PsA in people who are overweight. Studies have also found a link between improved disease activity and increased medication response after weight loss.
• Environmental factors, including trauma, chronic stress, and infection: Triggering events linked to PsA include injuries, heavy lifting, prolonged chronic stress, serious infections, and the Koebner phenomenon (the appearance of skin lesions after a skin trauma).
  

Reactive Arthritis

Specific causes of reactive arthritis are unknown. However, research suggests that the condition is in some part caused by a genetic predisposition. Many people who get reactive arthritis test positive for HLA-B27.

In sexually active males, reactive arthritis can follow an infection from Chlamydia trachomatis or Ureaplasma urealyticum, two bacteria that lead to sexually transmitted infections.

In other cases, a person can develop symptoms from an intestinal infection with Salmonella, Shigella, Yersinia, or Campylobacter after eating or handling contaminated food or coming into contact with the feces of an infected person.

Not everyone who develops a bacterial infection will go on to develop reactive arthritis. The condition only occurs in a small number of people exposed to causative bacteria.

Researchers don’t know why some people develop the condition while others don’t. They suspect that this is where HLA-B27 comes into play. Even so, the genetic link to reactive arthritis is not fully understood. Additional factors, environmental and immunologic, might contribute to the development of the condition.

Diagnosis

There is no definitive test, blood work, or other exam that can confirm a diagnosis of PsA. Instead, your healthcare provider will try a variety of testing methods to make a diagnosis. Similarly, reactive arthritis does not have a clear method for making a diagnosis.

Psoriatic Arthritis

A diagnosis of PsA starts with a review of your symptom history and a physical exam. During the exam, your healthcare provider will examine your joints for signs of swelling or tenderness and check your fingernails for nail changes. They press on the heels and soles of the feet to look for sore and tender spots.

Imaging studies can help healthcare providers determine bone and joint changes. X-rays can help them look for joint changes in PsA. Additionally, magnetic resonance imaging (MRI) can help provide images of the hands and soft tissues throughout the body and look for any problems with your feet and lower back.

Blood work that assists in diagnosing PsA include a rheumatoid factor (RF) test. RF is found in people with rheumatoid arthritis (RA), another type of inflammatory arthritis that attacks the lining of the joints, usually on both sides of the body. This test can help differentiate PsA from RA.

A joint fluid test can distinguish PsA from gout, an inflammatory condition that causes uric acid crystal buildup in joint fluid. PsA does not have uric acid crystal buildup. With this test, a healthcare provider uses a needle to remove a small fluid sample from an affected joint and sends it to a laboratory for testing.

Reactive Arthritis

A diagnosis of reactive arthritis can sometimes be difficult to make because of the way symptoms will present and the timeline of symptoms. Symptoms of reactive arthritis can last anywhere from three to 12 months and may come and go.

Symptoms may return and become chronic for around 30% to 50% of people, lasting more than six months. A diagnosis becomes less complicated when arthritis, eye, and urinary tract symptoms appear together or present close together.

There is no specific test that can confirm a diagnosis of reactive arthritis, but a healthcare provider can check urethral discharge for sexually transmitted infections (STIs). Stool samples can also be checked for infection.

Blood tests that look for HLA-B27 and levels of inflammation can also assist your healthcare provider in making a diagnosis.

X-rays are not usually helpful for diagnosing reactive arthritis because imaging will not reveal any joint abnormalities or changes unless symptoms recur.

But much like other spondyloarthropathies, repeated joint inflammation from chronic reactive arthritis might show bone loss, bone spurs (bony growths on the ends of bones), and signs of osteoporosis (weak and brittle bones). The joints of the back and pelvis might also show damage from reactive arthritis.

Treatment

Neither PsA nor reactive arthritis can be cured but both are treatable, although treatment is managed differently for each. Both conditions should be treated early and aggressively to slow down inflammation that could lead to joint damage down the road.

Psoriatic Arthritis

Treatment for PsA will depend on how severe PsA is, the type of PsA you have, and if you already have joint damage.

One of the first treatments for managing PsA is nonsteroidal anti-inflammatory drugs (NSAIDs), such as Bayer (aspirin), Advil or Motrin (ibuprofen), and Aleve (naproxen). These are recommended to people with mild disease and who have not experienced joint damage.

Your healthcare provider will monitor symptoms several times a year to make sure symptoms don’t increase. If your symptoms worsen, additional medicines will be added to your treatment plan.

Conventional disease-modifying antirheumatic drugs (DMARDs), such as Trexall (methotrexate), are given to people whose disease is moderately active and who experience pain, swelling, and skin symptoms more frequently. These drugs work through the immune system to prevent damage to the joints, spine, and tendons.

If joint damage has already occurred or if you are still experiencing significant joint pain and skin inflammation, biologics might be more effective for slowing down and preventing disease progression.

Newer treatments for PsA are Janus kinase (JAK) inhibitors, which can help ease joint pain and swelling. They work by tapering the immune system reaction to prevent joint damage.

There are many non-pharmacological therapies that, in addition to medicine, can help to manage symptoms.

Some nondrug therapies include:    

• Physical therapy can help regain your range of motion, prevent the return of symptoms, strengthen muscles, and stabilize the spine. Physical therapy can also be used in cases in which there is tendon damage to strengthen muscles and joints and to increase joint stability and balance.
• Topical treatments are frequently used to treat psoriasis skin symptoms. If you experience skin symptoms, it is important to have a dermatologist involved in your care to ensure the right treatments are being prescribed to manage psoriasis.

Reactive Arthritis

If a bacterial infection is still active, it may be treated with antibiotics. Joint inflammation is usually managed with NSAIDs. Skin symptoms and eye inflammation can be treated with corticosteroids.

If reactive arthritis has become chronic, your healthcare provider will treat it with stronger medicines, including DMARDs like methotrexate. They may also recommend physical therapy to manage joint symptoms.

Prevention

Autoimmune diseases, like PsA, are generally not preventable. However, it is possible to prevent reactive arthritis by managing risk factors for the condition. With PsA, some contributing factors may be outside of your control.

Psoriatic Arthritis

No treatment can guarantee that a person with psoriasis or a family history of psoriasis or PsA will not develop the condition. And because some people will develop PsA without having psoriasis, it can be difficult to identify who is at risk.

A 2019 medical review in the journal Nature looked at the many challenges healthcare providers face as they work with people to prevent PsA. The report’s authors note the difficulties in identifying triggers for the condition and who might be at risk for PsA.

One day, researchers will have more answers on preventing PsA and who might be at the most risk for the condition. For now, healthcare providers focus on managing symptoms of psoriasis in hopes of reducing the risk for PsA. People will psoriasis usually start to experience symptoms of PsA around 10 years after the start of psoriasis symptoms.

Reactive Arthritis

Unlike PsA, reactive arthritis might be preventable. The most effective way to reduce the risk for the condition is to avoid sexually transmitted infections (STIs) and gastrointestinal (GI) infections responsible for reactive arthritis.

STIs can be prevented by using condoms during sex. GI infections can be prevented by ensuring good hygiene practices when preparing and storing food and when changing diapers.

Summary

Psoriatic arthritis and reactive arthritis are types of spondyloarthritis, inflammatory diseases that affect the back, pelvis, neck, and other large joints. They also share similar symptoms and might be linked to similar gene mutations.

PsA tends to run in families and is caused by genetic factors, as well as environmental risk factors, such as trauma, chronic stress, and infections. Reactive arthritis is caused by different types of bacterial infections, specifically those linked to sexually transmitted infections and contaminated food or drink or contact with the feces of an infected person.

Diagnosing either condition requires ruling out other conditions. Blood work isn't always reliable when it comes to confirming either condition.

Treatment for PsA includes different types of medicines to manage the effects of an overactive immune system, reduce inflammation, and prevent joint damage. Treatment for reactive arthritis involves treating its underlying cause to prevent further chronic inflammation and recurrences.

PsA is generally not preventable. However, reactive arthritis can be prevented with safe sex measures to avoid STIs, properly handling and preparing food, and washing hands (especially after changing diapers) to prevent gastrointestinal infections.

A Word From Verywell

Knowing the type of arthritis you have is important because, if left untreated, certain types of arthritis can lead to severe joint damage or disability down the road.

Psoriatic arthritis is very aggressive and needs to be treated as such. It also puts you at risk for other conditions, including heart disease, so it is important to discuss your symptoms with your healthcare provider as soon as they start.

With reactive arthritis, your prognosis can vary. Some people recover within months, but others will have a recurrence, and ongoing inflammation could mean bone and joint damage.

Reach out to your healthcare provider as soon as you start to experience symptoms of PsA, reactive arthritis, and other types of inflammatory arthritis so that you can get a diagnosis early and start treatment. This will improve your prognosis and quality of life.