Lupus is a chronic autoimmune disease in which the immune system attacks the body’s own tissues. It is sometimes called “the great imitator” because its symptoms overlap with so many other conditions, and it can involve the skin, joints, kidneys, blood, heart, lungs and brain. With good care, most people with lupus now live long lives — but getting diagnosed, staying well and paying for treatment can all be difficult. This guide explains the essentials.

What lupus is

The most common and serious form is systemic lupus erythematosus (SLE). In SLE, the immune system produces autoantibodies against components of the body’s own cells. These form clumps called immune complexes that lodge in tissues and trigger inflammation. Other forms include cutaneous lupus, which is limited to the skin; drug-induced lupus, which usually resolves when the triggering medicine is stopped; and neonatal lupus, a rare condition in newborns of mothers with certain antibodies.

Who gets it

About nine in ten people with lupus are women, and it usually begins between the ages of 15 and 44. In the US it is two to three times more common, and often more severe, in Black, Hispanic, Asian and Native American women than in white women. Genes play a part, but most people with lupus have no affected relative; hormones, sunlight, infections and other environmental triggers appear to contribute. It is not contagious.

Symptoms

Lupus tends to come in flares, periods when symptoms worsen, separated by quieter spells. Common features include:

  • profound fatigue;
  • joint pain, stiffness and swelling;
  • a butterfly-shaped rash across the cheeks and nose, and rashes after sun exposure;
  • mouth ulcers and hair loss;
  • unexplained fevers;
  • fingers that turn white or blue in the cold (Raynaud’s);
  • chest pain on deep breathing, from inflammation around the lungs or heart.

No two patients are alike, and symptoms can change over time, which is one reason diagnosis is often delayed by years.

Lupus nephritis: the complication to watch

Up to about half of people with SLE develop lupus nephritis, inflammation of the kidneys’ filters. It is one of the most serious complications because it can progress silently to kidney failure. Early on there may be no symptoms; later signs include foamy urine, swelling in the legs or around the eyes, and high blood pressure. That is why people with lupus have their urine and blood tested regularly. If protein or blood appears in the urine, a kidney biopsy is usually needed to confirm the diagnosis and guide treatment.

How lupus is diagnosed

There is no single test. Doctors combine symptoms, examination and laboratory results. Almost everyone with SLE has a positive antinuclear antibody (ANA) test — but so do many healthy people, so a positive ANA alone does not mean lupus. More specific antibodies, such as anti-dsDNA and anti-Sm, low levels of immune proteins called complement, blood counts and urine tests help build the picture. Diagnosis is usually made by a rheumatologist.

How it is treated

Treatment aims to control flares, prevent organ damage and keep steroid use as low as possible:

  • Hydroxychloroquine, an old antimalarial, is recommended for nearly everyone with SLE. It reduces flares and improves long-term survival; regular eye checks are needed.
  • Corticosteroids such as prednisone work quickly but cause harm with long-term use, including bone thinning, diabetes, infections and weight gain, so the goal is the lowest dose for the shortest time.
  • Immunosuppressants such as mycophenolate, azathioprine and methotrexate are used for more serious disease.
  • Biologics and targeted drugs: Benlysta (belimumab) and Saphnelo (anifrolumab) are approved for SLE. For lupus nephritis, options include Benlysta, the pill Lupkynis (voclosporin) and, most recently, Gazyva (obinutuzumab).

What treatment costs

This is where patients often struggle. The foundation drugs are cheap: generic hydroxychloroquine, prednisone and mycophenolate typically cost tens of dollars a month. The newer targeted drugs are a different matter, with US list prices running to tens of thousands of dollars a year, and in some cases above $100,000. What a patient actually pays depends on insurance, and insurers often require prior authorization or proof that cheaper drugs were tried first. Manufacturer assistance programs, copay cards and nonprofit foundations can reduce out-of-pocket costs substantially, and a rheumatology clinic’s staff or a pharmacist can usually help with applications. Because lupus disproportionately affects women of color, who are more likely to be under-insured, cost is a significant driver of unequal outcomes.

Living with lupus

Daily habits matter. Sun protection is essential, since ultraviolet light can trigger flares. Not smoking, staying active, keeping vaccinations up to date and controlling blood pressure and cholesterol all help, because lupus raises the risk of heart disease and infection. Pregnancy is possible for most women with lupus but should be planned with the care team, ideally during a quiet period, as some medicines must be changed beforehand.

What is coming

Research is unusually active. The most dramatic results have come from CAR-T cell therapy, which has put some people with severe lupus into drug-free remission in small studies, though it remains experimental and its safety in this setting is unsettled (see our CAR-T explainer). Simpler approaches aimed at the same “immune reset,” and several new antibodies and pills, are in late-stage trials. Not every candidate succeeds; lupus has a long history of failed drug trials.

Anyone with persistent fatigue, joint pain and unexplained rashes, especially after sun exposure, should ask their doctor whether lupus could be the cause. This explainer is general information, not medical advice.