It is not unusual for people—sometimes even medical professionals—to mistake psoriatic arthritis (PsA) for systemic lupus erythematosus (SLE), simply referred to as lupus. These two conditions share many symptoms, including joint pain and skin symptoms. But they also have many differences and ways to tell them apart.

Both of these diseases cause inflammation throughout the body, as well as arthritis (joint pain and swelling). In PsA, the arthritis is erosive, leading to loss of bone and cartilage. In lupus, the arthritis is not erosive.

Lupus is an autoimmune disease in which the body produces abnormal antibodies (autoantibodies) that mistakenly attack the body’s own tissues. In PsA, there are no autoantibodies, but the inflammatory processes are overactive. It is considered immune mediated.

This article will discuss psoriatic arthritis vs. lupus, and their similarities and differences, including symptoms, causes, treatment, and more.

Symptoms

PsA is a chronic, inflammatory disease of the joints and the entheses—the places where tendons and ligaments connect to bone. It is common in people with the inflammatory skin disease psoriasis. 

Much like PsA, lupus is an inflammatory condition that causes inflammation and pain throughout your body. People with lupus experience joint pain, skin sensitivities, rashes, and problems with their internal organs.

Both PsA and lupus are autoimmune diseases, conditions in which the immune system malfunctions and attacks healthy tissues.

Psoriatic Arthritis

Between 0.06% and 0.25% of the American population has PsA. However, PsA is very common in people with psoriasis—affecting about 30%. Psoriasis occurs because the immune system speeds up skin cell growth and causes skin cells to build up as itchy, red scales on the skin.

  • Joint pain and swelling

  • Dactylitis (severe swelling of fingers and toes)

  • Knee, hip, elbow, and chest pain

  • Heel and foot pain from enthesitis (inflammation of the entheses)

  • Joint stiffness in the morning and after periods of inactivity

  • Chronic fatigue

  • Skin symptoms, with or without psoriasis

  • Eye inflammation, redness and pain, blurred or cloudy vision, sensitivity to light

  • Muscle and joint pain

  • Sun or light sensitivity

  • Mouth ulcers

  • Chronic fatigue

  • Anemia (lack of healthy red blood cells)

  • Increased blood clotting

  • Brain fog

  • Eye inflammation

  • Fever

  • Rashes

  • Hair loss

  • Chest pain

  • Lupus nephritis (complication affecting the kidneys)

Psoriatic arthritis can develop slowly and cause mild symptoms, or it can develop quickly and aggressively. Some people may develop the condition after an injury or an illness, but researchers believe the condition is related to genetics.

PsA is known for causing many problems in the body. Most people with the condition will have multiple symptoms that range from mild to severe. The most common symptom of PsA is joint pain, swelling, and stiffness.

Psoriatic arthritis is considered a type of inflammatory arthritis because joint inflammation occurs as a result of an overactive immune that affects many joints throughout the body at once.

Additional common symptoms of PsA are:

  • Chronic fatigue
  • Joint stiffness in the morning and after periods of inactivity
  • Enthesitis
  • Heel and foot pain from enthesitis
  • Knee, hip, elbow, and chest pain
  • Dactylitis
  • Skin symptoms, with or without psoriasis
  • Eye inflammation, including uveitis, which causes eye redness and pain, blurred or cloudy vision, and sensitivity to light

Lupus

According to the Lupus Foundation of America, lupus affects 1.5 million Americans and 5 million people worldwide. Most people with lupus are females of childbearing age, but the condition can affect anyone regardless of age or sex, including males, children, and teens.

Lupus is less common in White populations than in Black, Latinx, Native American, and Pacific Islander populations.

There are different types of lupus, the most common of which is SLE. Other types of lupus are:

  • Cutaneous lupus erythematosus: This type of lupus primarily affects the skin. It also causes hair loss.
  • Drug-induced lupus: This type of lupus is triggered by certain medications. Often, it goes away once you are no longer using the drug that has caused it.
  • Neonatal lupus: This type of lupus is rare, affecting infants at birth. It develops when the pregnant person has antibodies associated with lupus and passes them on to the child before birth. The pregnant person may know they have lupus or will be diagnosed later in life. This doesn’t occur in all such pregnancies.

The symptoms of lupus usually come and go. The condition flares up (symptoms worsen) and sometimes goes into remission (periods when it improves).

Lupus symptoms might include:

  • Muscle and joint pain: People with lupus experience both muscle and joint pain. Common areas affected are the neck, thighs, shoulders, and upper arms.
  • Fever: Lupus causes fevers greater than 100 degrees Fahrenheit. It is a common symptom of lupus, affecting 36%–86% of people with the condition.
  • Rashes: Lupus rashes can affect any part of the body exposed to the sun, including the face, arms, and hands. A common sign of the condition is a red, butterfly-shaped rash that appears on the nose and cheeks. Most people with SLE lupus will have this rash.
  • Hair loss: If someone has sores or rashes on their scalp, they may experience hair loss and hair thinning. Hair loss can also be a side effect of some of the medications used to treat lupus.
  • Chest pain: Lupus causes inflammation of the lining of the lungs, which leads to chest pain when breathing deeply.
  • Sun or light sensitivity: Most people with lupus are photosensitive, meaning they are affected by light. Exposure to sunlight and other sources of ultraviolet (UV) light can lead to skin rashes, fever, fatigue, and joint pain.
  • Kidney problems: Lupus nephritis (a type of kidney disease caused by lupus) affects around 40% of people with lupus and up to 10% of this group will develop end-stage kidney disease.
  • Mouth ulcers: These usually appear on the roof of the mouth, in the gums, inside the cheeks, and/or on the lips. These sores are usually painless, but they can be sore and cause pain in some people.
  • Chronic fatigue: Lupus causes fatigue that makes you feel tired and exhausted regardless of how much sleep you get.
  • Anemia: Anemia is common in people whose lupus is active. It occurs when the body doesn’t have enough red blood cells to carry oxygen throughout the body.
  • Blood clotting: Lupus increases blood clotting. This could mean blood clots in the lungs or legs.
  • Brain fog: Some people with lupus experience signs of brain fog, such as forgetfulness and confusion.
  • Eye problems: Systemic (whole-body) inflammation can affect the eyes and cause eye dryness and eyelid rashes.

Lupus is also known for causing symptoms and conditions that affect the brain, spinal cord, or nerves. Examples of these symptoms or conditions are:

  • HeadachesSeizureMemory lossMood changes and depressionMovement disorders (such as ataxia, dystonia, and Lewy body dementia)Spinal cord disorders (such as acute transverse myelitis, cauda equina syndrome, and spondylotic cervical myelopathy)

Causes

Both PsA and lupus start in the immune system—the body’s defense against foreign substances, such as bacteria and viruses. With autoimmune diseases like PsA and lupus, the immune system malfunctions and attacks its own healthy tissues.

In lupus, the immune system produces autoantibodies that attack the body’s own tissues. Treatment focuses on reducing the B cells that produce these antibodies. In PsA, the cascade of responses that produce inflammation is overactive. Treatment focuses on calming this inflammatory process.

The cause of PsA is unknown, but researchers suspect it develops from a combination of genetic and environmental factors. They also think immune system troubles, infections, physical and emotional traumas, and obesity might play a part in the development of the condition.

The people with the highest risk for PsA are people with psoriasis. About 30% of this group will go on to develop PsA. Of course, not everyone with PsA will have psoriasis first and some people with PsA never get psoriasis.

Research studies show people with PsA have increased levels of tumor necrosis factor (TNF) in their joints and affected skin areas. TNF is an inflammatory protein responsible for conditions like PsA and lupus. High levels of TNF can overwhelm the immune system and inhibit its ability to control inflammation.

Your risk for PsA is high if the PsA or psoriasis runs in your family. Over 40% of people with PsA have a family member with PsA or psoriasis.

PsA affects people of all sexes equally. It most commonly affects people in middle age, but anyone can get PsA regardless of age, including children. Psoriatic arthritis is diagnosed more often in White people than in people who are Black, Latinx, or South Asian.

Researchers believe lupus develops in response to a combination of factors, including hormones, genes, and environmental triggers.

Hormones: Researchers have looked at the relationship between estrogen and lupus. While people of all sexes produce estrogen, estrogen levels are higher in females. Additionally, females experience more lupus symptoms before their monthly periods and during pregnancy when their estrogen levels are highest.

However, the studies of people taking estrogen birth control or using postmenopausal therapy haven’t found any increase in lupus disease activity, so much of the research on estrogen and lupus has provided mixed answers.

Genetics: Researchers have identified more than 50 genes linked to lupus. These are genes mostly seen in people with lupus. While many of these genes are not shown to directly cause the disease, they are believed to contribute to it.

However, genes alone are not enough to cause the condition. Additionally, while family history increases your risk, you can still develop lupus without a family history of the condition.

Research has also found certain ethnic groups, including people of African, Asian, Native American, Hawaiian, or Pacific Island backgrounds, have a greater risk for lupus. Researchers believe this is because these groups have lupus-related genes in common.

Environment: Most researchers think lupus is linked to environmental triggers, such as viruses or chemicals. When these types of triggers encounter a genetically susceptible person, the disease develops.

Researchers have not yet identified specific triggers, but they have some theories. Potential triggers might include ultraviolet light, infections and other illnesses, sulfa drugs, medications that can make a person sun-sensitive, chronic stress, trauma, and exposure to silica dust (in industrial settings)

Diagnosis

There is no single test that can confirm PsA or lupus, but doctors will employ different testing methods to determine the source of your symptoms.

Each condition has diagnostic criteria that are used in classification. The classification criteria for psoriatic arthritis (CASPAR) may be used for psoriatic arthritis. The 2019 joint European League Against Rheumatism (EULAR) and American College of Rheumatology (ACR) classification criteria may be used for SLE.

Diagnosing PsA can be complex. Some telltale signs of PsA can help aid in a diagnosis, including inflammation of one or more joints, tendon inflammation, swollen fingers and toes, spine inflammation, and nail and skin symptoms. Your doctor will look for and ask you about these specific symptoms if they suspect PsA.

Your healthcare professional will also request a rheumatoid factor (RF) test. RF is a protein found in the blood of people with rheumatoid arthritis (RA), another type of inflammatory arthritis that attacks the lining of the joints.

Another blood test used to rule out RA is an anti-cyclic citrullinated peptide (anti-CCP) antibody test. Both RF and anti-CCP testing will be negative in people with PsA.An X-ray of the hands and feet can look for any bone or joint damage that has already occurred. Psoriatic arthritis often causes bone erosions and other joint damage not seen with other rheumatic conditions.

Your doctor may request additional testing and blood work to rule out other causes of symptoms if they are still unsure of your diagnosis.

Lupus can be hard to diagnose because it causes symptoms that are seen in other conditions, including other autoimmune diseases. People can have lupus for many years before they are diagnosed.

If you start to experience symptoms of lupus, your doctor needs to know right away. They will use many different testing methods to determine the source of your symptoms.

In reaching a diagnosis, your doctor will:

  • Review of your medical history: You should let your doctor know about the symptoms you are experiencing. Keep track of symptoms by writing them down, including information about when they occur and how long they last.Ask about family history: Tell your doctor about any family history of lupus or other autoimmune diseases.Complete a physical exam: Your doctor will examine your skin for rashes and your joints for inflammation.Request blood work: Antinuclear antibody (ANA) blood tests can look for autoantibodies of lupus, and 98% of people with lupus will have a positive ANA test. But a positive ANA test isn’t enough to confirm lupus. Your doctor will likely order additional antibody testing.Skin or kidney biopsy: A biopsy of the skin or kidney can be done to remove a sample of tissue to test under a microscope. If a person has lupus, the tissue sample will show genetic markers of the condition.

Your healthcare provider will also request additional testing to rule out other conditions that might be confused with lupus.

Treatment

Both PsA and lupus are lifelong conditions that require long-term care. Doctors can recommend the best treatments for each condition. Sometimes, these treatments overlap.

Psoriatic Arthritis            

Many treatment options are effective for treating symptoms of PsA. Your doctor will prescribe medications based on disease and symptom severity.

Treatment options for PsA include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs can be very effective for managing mild pain and inflammation. Examples of these drugs include Advil or Motrin (ibuprofen) or Aleve (naproxen). Many are available over the counter.
  • Disease-modifying antirheumatic drugs (DMARDs): DMARDs slow down joint damage linked to PsA. The most commonly prescribed DMARD is Otrexup (methotrexate).
  • Biologics: Doctors primarily use biologics to treat moderate to severe PsA. These drugs target specific parts of the immune system to reduce PsA flare-ups. They also block proteins that contribute to inflammation and swelling and help to reduce pain.
  • Janus kinase (JAK) inhibitors: JAK inhibitors work by tapering down the immune system and preventing inflammation that leads to joint damage.
  • Otzela (apremilast): Otzela works by blocking an enzyme called phosphodiesterase type 4 (PDE4) to control inflammation.

People with PsA who have skin symptoms might also be treated with topical treatments, including corticosteroid creams and anti-inflammatory medications. Skin symptoms can also be treated with phototherapy (exposing the skin to UV light), which can reduce and manage itching and skin pain.

Surgery is rarely an option for treating PsA, but it is recommended in situations in which joints have been severely damaged and to relieve pain and improve your mobility.

Additional interventions for treating and managing PsA are:

  • Physical therapyOccupational therapyA healthy diet and weight lossA light exercise program that includes activities, such as yoga, swimming, walking, or running

There are several types of medicines used to treat lupus. Your healthcare provider will determine what drugs might best help based on your symptom and disease severity. 

Different types of treatments for lupus might include:

  • NSAIDs: Over-the-counter NSAIDs can help manage mild pain and reduce muscle and joint swelling.
  • Corticosteroids: Corticosteroids, like prednisone, can help reduce pain, swelling, and tenderness by quieting the immune system. Lupus symptoms can respond very quickly to corticosteroids. Due to side effects, they are prescribed only for short periods.
  • Antimalarial drugs: Medications like hydroxychloroquine and chloroquine phosphate can treat joint pain, skin rashes, fatigue, and all-over inflammation.
  • BLyS-specific inhibitors: These drugs limit abnormal B-cells (immune cells that create antibodies) found in people with lupus. The most-prescribed medication in this class for lupus is Benlysta (belimumab), which blocks the action of a specific protein that causes lupus symptoms.
  • Immunosuppressive drugs: These medicines are used in severe cases of lupus. Doctors recommend these for people having serious symptoms that affect organs, including the brain, kidneys, heart, or lungs.
  • Other medicines: Your healthcare professional might prescribe treatments for other conditions linked to your lupus, including high blood pressure. Lupus also increases your risk for blood clots, so your doctor might prescribe blood thinners to prevent your blood from clotting too easily.

Prevention

Both PsA and lupus are linked to genetic and environmental factors and that means it may not be possible to prevent them.

Researchers know that people with psoriasis have a higher risk for PsA and some people have genetic markers that put them at risk for the condition. However, there is no treatment or tool to prevent someone from getting PsA. And there is no way to predict who may go on to develop the condition.

Some triggers and risk factors for PsA can be prevented—things like smoking, diet, and chronic stress. But even with managing these types of triggers, a person can still end up with PsA.

If PsA or psoriasis runs in your family and you have concerns about your risk, reach out to your healthcare provider for a discussion and evaluation. This way you can get ahead of any problems and reduce the risk for serious joint damage, which is often seen early in PsA.

Much like PsA, lupus is not preventable. Researchers have tried to identify early signs of lupus in hopes of intervening to prevent the start of the condition.

For example, they have looked at people who are predisposed genetically and who might experience environmental insults, such as infections. These types of studies have been helpful, but they have not provided answers on ways to prevent the condition.

Because of the limited answers, doctors recommend that people with a family history of the condition do what they can to reduce their risk. This includes things like not smoking, getting adequate sleep, eating healthily, and maintaining a healthy weight.

Summary

Psoriatic arthritis and lupus are both autoimmune conditions that affect the skin and joints. While they share some similar symptoms, they are separate conditions. It is possible to have both conditions because their disease processes are similar.

Once a diagnosis can be confirmed, both PsA and lupus can be treated and managed effectively. They are both lifelong conditions, and neither can be cured. If either of these conditions runs in your family, talk to your doctor about your specific risk and what you can do to reduce it.

A Word From Verywell  

If you are diagnosed with psoriatic arthritis or lupus, make sure you check in with your doctor regularly. These conditions need to be treated aggressively so that you do not experience disease complications.

Both PsA and lupus affect your organs, so it is a good idea to discuss your risk for other conditions, what symptoms to watch out for, and preventive measures to take. With the help of a rheumatologist or other specialists, you can manage PsA or lupus successfully. Managing your condition can improve your outlook and quality of life.

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By Lana Barhum

Lana Barhum has been a freelance medical writer since 2009. She shares advice on living well with chronic disease.