Lupus is an autoimmune disease in which the immune system attacks the body’s own healthy tissues, causing inflammation that can damage the skin, joints, kidneys, brain, heart, and other organs. About 204,000 people in the United States have systemic lupus erythematosus (SLE), the most common and serious form. Nine out of ten are women, and Black and American Indian/Alaska Native women are two to three times more likely than White women to develop it.
How the Immune System Turns on Itself
In a healthy immune system, cells called B cells and T cells work together to identify and destroy threats like bacteria and viruses. In lupus, this partnership goes haywire. When cells naturally die and break apart, the leftover material, particularly DNA and proteins from inside the cell nucleus, gets presented to T cells as though it were a foreign invader. These T cells then activate B cells, which begin producing antibodies against the body’s own tissues.
The B cells, in turn, can activate more T cells, creating a feedback loop that continuously ramps up the immune response. The result is a flood of autoantibodies, the most notable being antinuclear antibodies (ANA), found in over 97% of lupus patients. Another type, anti-double-stranded DNA antibodies, appears in 60 to 70% of patients and is closely linked to kidney damage and overall disease severity. These autoantibodies form clumps called immune complexes that deposit in organs, triggering inflammation and tissue destruction.
Skin and Joint Effects
Joint pain, stiffness, and swelling are among the most common symptoms of lupus and often one of the first things people notice. Unlike rheumatoid arthritis, lupus-related joint inflammation typically doesn’t erode bone, but it can be painful enough to limit daily activities. It tends to affect multiple joints at once, particularly the hands, wrists, and knees.
The butterfly rash is perhaps the most recognizable sign. It spreads across both cheeks and the bridge of the nose, often worsening with sun exposure. Many but not all people with lupus develop it. Other skin problems include mouth sores, hair loss that doesn’t leave scars, and a scaly, disc-shaped rash that can appear on the face, scalp, and ears.
Kidney Damage
Up to 45% of people with lupus develop kidney inflammation, known as lupus nephritis. This is one of the most dangerous complications because it often progresses silently. The kidneys can sustain significant damage before any symptoms appear. By the time a person is first diagnosed with lupus, up to 35% already have some degree of kidney involvement.
When symptoms do show up, they may include foamy urine, swelling in the legs and feet, or high blood pressure. Kidney involvement is driven by those immune complexes depositing in the tiny filtering units of the kidneys, provoking inflammation that gradually scars the tissue. Without treatment, lupus nephritis can progress to kidney failure.
Effects on the Brain and Nervous System
Lupus can affect the brain and nervous system in at least 19 different recognized ways, and 80 to 90% of lupus patients experience some form of neurological or psychiatric involvement over the course of the disease. The most common manifestations are depression (affecting 50 to 60%), headache (50 to 70%), and cognitive dysfunction (30 to 50%). Less frequent but more severe manifestations include seizures, strokes, psychosis, and acute confusion.
Cognitive dysfunction, sometimes called “lupus fog,” shows up as trouble concentrating, difficulty finding words, and problems with memory. It can be subtle enough to go unnoticed in a doctor’s office, but it often interferes with work, school, and daily functioning. The good news is that it can be detected early through neuropsychological testing, well before it progresses to more serious confusion or dementia.
Heart and Blood Vessel Risks
People with lupus face two to three times the risk of heart attack and stroke compared to the general population. For younger patients, those with more severe disease, or those with kidney involvement, that risk jumps dramatically, as high as 50 times the general population’s rate. The chronic inflammation caused by lupus accelerates the buildup of plaque in arteries, a process that would normally take decades but can develop much earlier in lupus patients.
Lupus can also inflame the lining around the heart (pericarditis) or cause fluid to accumulate around the heart or lungs. These complications can cause chest pain, shortness of breath, and fatigue that goes beyond the baseline tiredness many lupus patients experience.
What Triggers Flares
Lupus is unpredictable. It cycles between periods of relative calm and sudden flares where symptoms worsen. Ultraviolet light is one of the most well-documented triggers. UV-B rays directly damage skin cell DNA and trigger a chain of cell death that releases the very nuclear material the immune system has learned to attack. UV-A rays work differently, damaging the energy-producing structures inside cells and generating harmful molecules called reactive oxygen species that also cause cell death. Both pathways dump cellular debris into the system, and in a person with lupus, that debris restarts the inflammatory cycle.
Beyond sunlight, common triggers include physical or emotional stress, infections, and certain medications, including some antibiotics. Sun protection is a practical daily priority for most people with lupus, not just for preventing skin rashes but for reducing the risk of a systemic flare that could affect internal organs.
How Lupus Is Diagnosed
Diagnosing lupus is notoriously difficult because its symptoms overlap with many other conditions. The current classification system, developed jointly by the European and American rheumatology societies, uses a point-based approach. A positive ANA blood test at a certain threshold is the entry requirement. From there, doctors tally points across clinical categories: skin rashes, joint problems, kidney findings, blood abnormalities, neurological symptoms, and fluid around the heart or lungs. A score of 10 or more, with at least one clinical symptom, classifies the disease as lupus.
A positive ANA test alone doesn’t mean lupus. ANA shows up in many other conditions and even in a significant portion of healthy people. It has a specificity of only about 20% for lupus. Anti-double-stranded DNA antibodies are far more specific, at over 95%, but only appear in about 60 to 70% of cases. This is why diagnosis relies on the full picture rather than any single test.
Treatment Approach
An antimalarial medication called hydroxychloroquine is the backbone of lupus treatment and is recommended for virtually all patients. It reduces disease activity, prevents flares, lowers the need for steroids, and helps maintain long-term remission. The standard dose is based on body weight, with a maximum of 400 mg daily for those over about 175 pounds, kept at that ceiling to minimize the risk of eye-related side effects over time.
For more severe or treatment-resistant lupus, two newer biologic therapies have changed the landscape. One, belimumab, has shown strong results in overall disease control. The other, anifrolumab, is particularly effective at helping patients reduce their steroid doses, which matters because long-term steroid use carries its own serious side effects, including bone thinning, weight gain, and increased infection risk. Treatment plans are highly individualized, depending on which organs are involved and how severe the inflammation is.
Most people with lupus take some combination of medications to suppress immune activity, manage inflammation, and protect specific organs. The goal isn’t to cure the disease, since no cure exists, but to minimize damage during flares and extend the stretches of quiet in between.