Some people do develop both lupus and rheumatoid arthritis, a combination that rheumatologists have come to call “rhupus syndrome.” It is uncommon, but it is real, and a growing body of evidence supports the idea that it represents a genuine overlap of two distinct autoimmune diseases rather than an unusual presentation of just one. The overlap creates a clinical picture that can be tricky to diagnose and harder to treat, with implications that go beyond what either disease would cause on its own.
What Rhupus Actually Means
The term “rhupus” was coined decades ago as a kind of shorthand for the coexistence of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in the same patient. For years, many specialists questioned whether it was a real entity or just lupus with unusually aggressive joint involvement. That debate has largely shifted. A systematic review of the literature found that rhupus is underdiagnosed and that studies increasingly point toward a true overlap between the two diseases, not merely one disease mimicking the other.1Autoimmunity Reviews. Rhupus: a systematic literature review The hallmark of rhupus is erosive, destructive joint disease characteristic of RA alongside the systemic features of lupus, such as skin rashes, blood abnormalities, and kidney inflammation.
Estimates of how common rhupus is depend heavily on where you look. One figure commonly cited in case-report literature puts the prevalence at roughly 0.09% of the general population.2PubMed Central. Three Case Reports of Rhupus Syndrome: An Overlap Syndrome of Rheumatoid Arthritis and Systemic Lupus Erythematosus But when researchers specifically screened a group of 103 lupus patients, about one in ten turned out to meet criteria for rhupus.3Autoimmunity Reviews. Rhupus syndrome: Assessment of its prevalence and its clinical and instrumental characteristics in a prospective cohort of 103 SLE patients That gap suggests the condition is underrecognized, especially in patients who are already being followed for lupus and whose joint symptoms might be attributed to lupus alone rather than to a second, coexisting disease.
How Rhupus Differs from Lupus Joint Pain
Joint pain is one of the most common complaints in lupus. Up to 90 percent of people with SLE experience joint symptoms at some point. But lupus joint disease, sometimes called Jaccoud’s arthropathy, tends to cause deformity through ligament laxity rather than bone destruction. The joints can look twisted or misaligned, but an X-ray often shows no actual erosion of the bone surface. In rhupus, the picture is different. The joint damage follows the RA pattern: the immune system attacks the synovial lining, leading to progressive bone erosion that shows up clearly on imaging. That erosive damage is the key feature separating rhupus from ordinary lupus joint involvement.4PubMed Central. Case report: Joint deformity associated with systemic lupus erythematosus
In most rhupus patients, the overall pattern of the joint disease tracks more like RA than like lupus. A systematic review described the natural history of rhupus arthritis as following an RA-like course, with progressive inflammatory erosions, deformities, and eventual disability if untreated.1Autoimmunity Reviews. Rhupus: a systematic literature review Meanwhile, the SLE-related involvement tends to be milder than what you would expect in full-blown lupus. Skin manifestations, low blood counts, and kidney or serosal inflammation are common, but often less severe than in patients who have lupus alone. That said, “milder” is a relative term, and some rhupus patients do develop serious organ complications.
The Antibody Fingerprint
One of the strongest arguments that rhupus is a genuine overlap rather than one disease in disguise comes from the antibody profiles. Each disease has its own signature autoantibodies. In RA, the most specific marker is anti-CCP (antibodies against cyclic citrullinated peptides). In lupus, anti-double-stranded DNA antibodies are a hallmark. Rhupus patients typically carry both.
A cross-sectional study of rhupus patients found that the presence of both anti-CCP and anti-dsDNA antibodies, alongside clinical features of each disease, strongly supported the idea that rhupus is a true overlap.5PubMed Central. Presence of antibodies against cyclic citrullinated peptides in patients with ‘rhupus’: a cross-sectional study A 2024 case study illustrated this vividly: a patient presented with both RA and SLE symptoms, and lab work showed anti-dsDNA levels of 214 IU/mL alongside anti-CCP levels above 3,000 U/mL.6PubMed. The Diagnostic and Therapeutic Value of Anti CCP Antibodies and Double Stranded DNA in Rhupus Syndrome That dual positivity is unusual in either disease alone and serves as an important diagnostic clue.
A recent review described the hybrid phenotype of rhupus as including dual autoantibody profiles: rheumatoid factor, anti-citrullinated protein antibodies, and anticarbamylated protein antibodies from the RA side, plus antinuclear antibodies and extractable nuclear antigen antibodies from the SLE side.7PubMed. Rhupus syndrome: current knowledge and future perspectives When a patient lights up on both sets of markers, that is the clearest signal that two processes are at work.
Why the Same Person Gets Both Diseases
The fact that RA and lupus can coexist in one patient is not random bad luck. These diseases share genetic risk factors, and the overlap helps explain why some immune systems go wrong in both directions at once.
A large study published in the New England Journal of Medicine identified a genetic variant in a gene called STAT4 that raises susceptibility to both RA and SLE. The risk version of this variant appeared on about 27 percent of chromosomes in RA patients compared with 22 percent in healthy controls, and on 31 percent of chromosomes in lupus patients versus 22 percent in controls.8PubMed Central. STAT4 and the risk of rheumatoid arthritis and systemic lupus erythematosus The same association was confirmed in a Japanese population, with similar effect sizes.9PubMed. Association of STAT4 with susceptibility to rheumatoid arthritis and systemic lupus erythematosus in the Japanese population STAT4 encodes a protein involved in immune-cell signaling, and having the risk variant pushes the immune system toward the kind of overactivation that drives both diseases.
Beyond STAT4, genetic studies have implicated other shared susceptibility genes, including HLA-DRB1 shared-epitope alleles (long known as the strongest genetic risk factor for RA) and a variant in PTPN22, which is involved in regulating immune-cell activation.7PubMed. Rhupus syndrome: current knowledge and future perspectives If you inherit several of these risk variants, your immune system may be primed to develop autoimmunity in general, with the specific disease that emerges depending on additional genetic and environmental factors. In some people, the dice roll lands on both.
Environmental triggers also play a role. Cigarette smoking has been linked to increased risk of both RA and lupus, and factors like infections and chemical exposures can tip a genetically susceptible person toward autoimmune activation.10PubMed Central. Smoking under hypoxic conditions: a potent environmental risk factor for inflammatory and autoimmune diseases
The Diagnostic Puzzle
Diagnosing rhupus is harder than it sounds, partly because there is no universally agreed-upon set of classification criteria. Researchers have used various combinations of existing RA and SLE criteria, but the approaches differ enough that it is hard to compare studies. A 2024 review examined this problem and proposed that combining the latest classification criteria for each disease, along with positive anti-CCP, anti-Smith, and anti-dsDNA antibodies, would be the most relevant approach, though it still needs validation.11PubMed. Examining the clinical and radiological landscape of rhupus: navigating the challenges in disease classification
In practice, rhupus is often diagnosed sequentially. A patient may carry a lupus diagnosis for years before developing clearly erosive arthritis, or they may be treated for RA and later develop lupus features like a butterfly rash, kidney inflammation, or plummeting blood counts. The systematic review noted that most patients develop features of both diseases sequentially rather than simultaneously.1Autoimmunity Reviews. Rhupus: a systematic literature review This temporal gap makes early recognition difficult. A rheumatologist managing someone with RA is not necessarily expecting lupus to appear, and vice versa.
The lack of formal diagnostic consensus also means that different clinics may label the same patient differently. Some may call it “overlap syndrome” or “undifferentiated connective tissue disease” rather than rhupus. This has real consequences for research: when studies use different definitions, comparing their results becomes unreliable.
Complications That Compound
Having two autoimmune diseases at once does not simply mean experiencing two lists of symptoms side by side. The combination can amplify certain risks, particularly cardiovascular and kidney complications.
Both RA and lupus independently raise the risk of heart disease, through chronic inflammation, accelerated atherosclerosis, and, in lupus, antiphospholipid antibodies that promote blood clotting. One case report described a rhupus patient who developed multiple coronary artery aneurysms and an acute heart attack, leading the authors to hypothesize that rhupus may carry an even greater cardiovascular risk than either disease alone.12PubMed. Multiple coronary aneurysms and acute myocardial infarction in a female patient with rhupus: case report and literature review Another report highlighted the importance of antiphospholipid antibodies in rhupus patients, noting that the combination of diseases may lead to more serious cardiac events and stroke.13PubMed Central. Rhupus syndrome and Chiari’s network
Kidney involvement is another area of concern. Lupus nephritis, where the immune system attacks the kidneys, is one of the most serious complications of SLE. It can also occur in rhupus. A case report documented a young man with rhupus who developed class IV lupus nephritis, the most aggressive form, along with fluid around the lungs and dangerously low blood cell counts.14PubMed Central. Single Rhupus syndrome in a young man complicated by class IV lupus nephritis and pleural effusion: complete remission with cyclosporine-based therapy: a case report A separate case described a 20-year-old woman with rhupus who presented with severe eye inflammation and lupus nephritis, requiring high-dose intravenous steroids to achieve remission.15PubMed Central. Rhupus syndrome presenting with anterior scleritis and lupus nephritis: A case report These are individual cases, not population-level evidence, but they illustrate that rhupus can hit hard when the lupus component flares aggressively.
How Rhupus Is Treated
There is no treatment protocol designed specifically for rhupus, and no drug has been approved for this indication. In practice, clinicians borrow from the toolkits for both RA and lupus and try to manage both disease components simultaneously. Hydroxychloroquine, used widely in lupus, and methotrexate, a cornerstone of RA treatment, are the most commonly prescribed conventional disease-modifying drugs in rhupus patients.16The Journal of Rheumatology. RHUPUS SYNDROME: DESCRIPTION OF CLINICAL MANIFESTATIONS, ANALYTICAL FINDINGS, AND THERAPEUTIC APPROACH IN A SERIES OF 10 CASES
When those first-line drugs are not enough, biologics come into play. Rituximab, which depletes B cells (a type of immune cell involved in both diseases), has shown promise. A pilot study of rituximab in refractory rhupus patients found sustained improvement in both RA and SLE disease-activity scores, better physical function, and reduced steroid doses over the follow-up period.17PubMed. Rituximab treatment for ‘rhupus syndrome’: clinical and power-Doppler ultrasonographic monitoring of response. A longitudinal pilot study Belimumab, a biologic approved for lupus that targets a B-cell survival factor, has also been tried in rhupus, particularly when skin involvement is prominent.18PubMed. Belimumab treatment in rhupus: A case report with severe skin involvement Other biologics mentioned in case-series literature include abatacept, which is used in RA to block T-cell activation.
The challenge with treatment is that what helps one disease component can sometimes be neutral or even counterproductive for the other. The immune pathways driving RA and lupus are not identical. Research comparing the immune profiles of RA and SLE monocytes found disease-specific patterns of gene expression driven by different cytokines: lupus is strongly associated with type I interferon signaling, while RA is more driven by tumor necrosis factor (TNF).19PubMed. The multifaceted balance of TNF-α and type I/II interferon responses in SLE and RA: how monocytes manage the impact of cytokines This matters practically because TNF-blocking drugs, which are among the most effective treatments for RA, carry a risk of triggering lupus-like symptoms in some patients. Anti-TNF-induced lupus is a recognized phenomenon that needs to be distinguished from a true overlap syndrome.20Oxford Academic. Anti-TNF-induced lupus This creates a therapeutic tightrope: you want to control the RA erosions aggressively, but some of the best RA drugs may provoke the lupus side.
When RA Treatment Triggers Lupus-Like Symptoms
If you have RA and are started on a TNF-blocking biologic such as infliximab, adalimumab, or etanercept, there is a small but real chance of developing lupus-like symptoms including rash, joint pain, fever, and positive antinuclear antibody tests. This is called anti-TNF-induced lupus. It usually resolves when the drug is stopped, and it is not the same as having true lupus. The distinction matters because a patient who develops these symptoms may be misdiagnosed with rhupus when they actually have a drug reaction, or conversely, a patient with genuine emerging lupus may have the symptoms dismissed as a drug side effect.
Clinicians need to differentiate true anti-TNF-induced lupus from cases where TNF-blocking therapy unmasks a pre-existing lupus tendency or overlap syndrome that was not yet clinically apparent.20Oxford Academic. Anti-TNF-induced lupus The antibody profile helps: anti-TNF-induced lupus typically involves antihistone antibodies rather than the anti-dsDNA and anti-Smith antibodies that mark true SLE. If someone on a TNF blocker develops lupus symptoms with anti-dsDNA positivity and persistent features after stopping the drug, the diagnosis tilts toward genuine overlap rather than a drug reaction.
Rhupus Alongside Other Autoimmune Diseases
The autoimmune clustering does not always stop at two diseases. Some rhupus patients also develop Sjögren’s syndrome, an autoimmune condition that attacks moisture-producing glands and causes severe dry eyes and dry mouth. This triple overlap has been nicknamed “Sjrupus” in the literature. A report on managing these complex overlaps noted that rituximab appeared effective across all three disease components and had the advantage of reducing the number of other drugs a patient needed to take.21The Journal of Rheumatology. Lupus, “Rhupus” and “Sjrupus” The existence of these multi-disease overlaps reflects a broader principle in autoimmunity: once the immune system loses tolerance in one direction, it is more likely to lose it in others. People with one autoimmune disease are statistically more likely to develop a second or third than the general population.
Raynaud’s phenomenon, where fingers and toes turn white or blue in response to cold or stress due to blood-vessel spasm, is another common companion. It appears in both lupus and RA independently and is frequently noted in rhupus case reports as well. For the patient, these additional conditions pile on symptoms and complicate treatment further, since each one may require its own management approach.
Living with Two Diseases at Once
From the patient’s perspective, rhupus means navigating a condition that few doctors have extensive experience with and that has no dedicated treatment guidelines. You may find yourself seeing a rheumatologist who is more comfortable managing RA, or one more experienced with lupus, and getting optimal care requires attention to both disease components. The RA side demands aggressive control of joint inflammation to prevent irreversible erosive damage. The lupus side requires monitoring for kidney involvement, blood abnormalities, and cardiovascular risk.
Regular screening bloodwork typically includes inflammatory markers, kidney function tests, complete blood counts, and antibody levels. Imaging of the hands and feet, whether by X-ray, ultrasound, or MRI, can track whether erosive damage is progressing. Because the cardiovascular risk may be amplified in rhupus compared with either disease alone, proactive management of blood pressure, cholesterol, and clotting risk is especially relevant for these patients.
Pregnancy planning also becomes more complex. Both lupus and RA carry their own pregnancy-related risks, and many of the medications used for these conditions are not safe during pregnancy. Coordination between a rheumatologist and a high-risk obstetrician is standard practice for anyone with either disease who wants to conceive, and it becomes even more critical when both are present. Hydroxychloroquine is one of the few drugs considered safe throughout pregnancy and is typically continued, while methotrexate must be stopped well in advance due to its potential to cause birth defects.
For someone newly diagnosed, the most practical takeaway is that rhupus is manageable but requires a treatment plan that accounts for both diseases explicitly. Raising the possibility with your rheumatologist, particularly if your joint symptoms seem more destructive than typical lupus arthritis or if your RA is accompanied by unexplained rashes, kidney problems, or blood-count drops, can prompt the additional testing needed to identify the overlap and adjust treatment accordingly.