Lupus and rheumatoid arthritis (RA) are both autoimmune conditions. Systemic lupus erythematosus (SLE) can affect multiple areas of the body, including the skin and internal organs. RA usually affects the joints, although inflammation can affect other areas too.
Researchers refer to the overlap of conditions as rhupus syndrome. According to a 2018 article, rhupus syndrome is a rare occurrence, affecting 0.09% of people. Researchers are unsure if lupus is the cause of rheumatoid arthritis (RA) in rhupus syndrome, or if the two conditions co-exist.
The term lupus includes several types, including systemic lupus erythematosus (SLE), which is the most familiar of all the lupus types. Other types include drug-induced, discoid, and neonatal lupus. This article includes information about SLE only, rather than any of the other types of lupus.
SLE can affect multiple areas of the body, including the joints, skin, and internal organs. People with SLE have an overactive immune system that attacks healthy tissue, causing inflammation. As the inflammation travels through the body, various tissues and organs can become inflamed.
SLE can affect people differently, and it is difficult to predict which areas of the body will become inflamed.
In RA, the immune system attacks the synovium, which is the lining that covers joints. This attack causes inflammation and prevents the synovium from working correctly to lubricate the joints and maintain a normal alignment. In turn, joints can be damaged and become unstable, leading to pain, stiffness, and restriction of normal movement.
Some common symptoms are shared by SLE and RA, although each condition also has its own symptoms, as shown in the table below.
|Occurs with both SLE and RA
|More common in SLE
|More common in RA
|Shortness of breath
|Swelling and stiffness in many joints
In addition, both SLE and RA commonly affect the same joints, which are usually the smaller joints in the body, including fingers, wrists, knees, ankles, and toes. In addition, a person will generally experience symmetrical symptoms, such as pain in both wrist joints rather than in only one.
Differences between the two conditions include their effects on skin, internal organs, and joint pain:
- Effect on skin: SLE can affect the skin, whereas RA usually does not do so. An SLE rash characteristically presents with a butterfly-shaped rash on the cheeks and nose.
- Internal organs: While both conditions can cause inflammation of the heart and lungs, a person with SLE is more likely to experience these symptoms than someone with RA. In addition, SLE can affect internal organs such as the kidneys, lungs, and heart. Although RA can affect internal organs, it does not commonly affect the kidneys.
- Joint pain: The main symptom of RA is joint pain and stiffness. Stiffness is not a prominent symptom of SLE.
Although both SLE and RA have some shared symptoms, each condition also has a specific set of symptoms relating to each condition, as explained below.
- painful or swollen joints
- swollen hands, feet, or around the eyes
- low fever
- sensitivity to sunlight or fluorescent light
- pain in the chest during deep breathing
People may also have symptoms relating to the skin or hair:
- a butterfly-shaped rash across the cheeks and nose
- hair loss
- ulcers or sores in the mouth or nose
- numbness or change in color of fingers and toes when cold or stressed
Symptoms of RA may come and go. According to the Arthritis Foundation, symptoms of RA include:
- pain, stiffness, or swelling in the joints for 6 weeks or more
- stiff joints in the morning lasting for 30 minutes or more
- multiple joint involvement
- symmetrical symptoms in the same joints on both the left and right sides of the body
- symptoms occurring in smaller joints first, such as the hands, wrists, and feet
- fatigue (lack of energy)
- low fever
The cause of SLE is uncertain, as is the case with RA, although some suggested causes include genetics and environment. There are several risk factors, including age, gender, lifestyle, and diet.
According to older 2013 data from the Lupus Foundation of America, researchers are not sure what causes lupus.
There may be a genetic factor, as SLE is more likely to affect people with family members who have SLE or another autoimmune condition. Elements such as hormones or environmental factors may also trigger SLE symptoms.
The Lupus Foundation also states that SLE is also more common in females ages 15–44 years, and certain ethnic and racial groups, including:
- African American
- Asian American
- Native American
- Pacific Islander
There is no clear cause for RA. According to the Arthritis Foundation, people may have certain genes that respond to environmental triggers, such as a virus or stress, which can cause RA.
Risk factors for RA include:
- being between ages 40–60 years
- being female
- having a family member with RA
- being overweight
- eating a diet high in red meat and low in vitamin C
Both conditions may be treated with medications. Physical therapy, regular exercise, and rest can also help to support the joints and ease stiffness.
The range of medications to help manage SLE symptoms include:
- antimalarial drugs, such as hydroxychloroquine, to help manage fatigue, lupus-related arthritis, rashes, ulcers, and help prevent lupus flares
- corticosteroids, such as prednisone, and immunosuppressants, such as azathioprine, to suppress the immune system and treat symptoms affecting internal organs and the central nervous system
- non-steroidal anti-inflammatory drugs (NSAIDs), to decrease inflammation and relieve pain
- biologics, such as belimumab, to treat lupus in adults and children
Treatment for RA can include medications, such as:
- NSAIDs, to reduce pain and inflammation
- disease-modifying antirheumatic drugs, to slow down joint damage
- corticosteroids, to reduce pain and inflammation
Both SLE and RA have symptoms that overlap with each other and with other conditions, which can make diagnosis difficult. A doctor will take a full medical history and carry out a physical examination to reach a correct diagnosis.
There is no single test for SLE, although blood tests can show antibodies that may indicate SLE, and skin or kidney biopsies may indicate organ involvement.
A doctor may use several criteria to diagnose SLE. If a person meets four of the following 11 criteria, it may indicate SLE:
- butterfly-shaped rash on the cheeks and nose
- raised rash
- sensitivity to sunlight, which may cause a rash or flare-up of symptoms
- painless mouth or nose ulcers
- joint inflammation affecting two or more joints
- inflammation of the heart lining or lungs
- neurologic condition, such as seizures or psychosis
- kidney disorder
- immunological disorder
- antinuclear antibodies positive in blood test
Doctors may carry out blood tests to check for certain indicators of RA in a person’s body, including:
- rheumatoid factor
- anti-cyclic citrullinated peptide antibodies
- C-reactive protein, to show inflammation levels
- erythrocyte sedimentation rate, to show inflammation levels
Doctors may also use imaging tests such as X-rays and MRI scans to check for joint damage.
It is important to see a doctor as soon as possible if people have any symptoms of SLE or RA. Prompt diagnosis and treatment may help prevent complications or progression of both conditions.
SLE and RA are both autoimmune conditions that cause the immune system to attack healthy tissue in the body, leading to inflammation. SLE can affect multiple areas of the body, including the skin and internal organs, while RA usually affects the joints, although inflammation can affect the eyes, mouth, heart, and lungs. Medication and therapy may help manage symptoms.