Overview
Systemic lupus erythematosus (SLE) is a chronic autoimmune condition in which the immune system attacks healthy tissue throughout the body. It can affect almost any organ, including the skin, joints, kidneys, heart, brain, and blood. It follows a relapsing-remitting course and ranges from mild to life-threatening. It is far more common in women, especially during the reproductive years.
How common is it?
SLE affects approximately 50,000 people in the UK. It is 9 to 10 times more common in women than men and disproportionately affects women of African, Caribbean, Asian, and Hispanic origin, in whom it tends to be more severe.
Causes and risk factors
SLE results from loss of immune tolerance, leading to autoantibody production against nuclear antigens. Both genetic and environmental triggers contribute.
Common risk factors
- Genetic susceptibility (HLA-DR2, HLA-DR3; numerous other susceptibility genes)
- Female sex hormones (estrogen promotes B-cell activity)
- Ultraviolet light exposure (triggers and worsens flares)
- Infections (Epstein-Barr virus association)
- Medications: hydralazine, procainamide, isoniazid (drug-induced lupus)
- Hormonal contraception (may exacerbate in susceptible individuals)
- Ethnic background (Afro-Caribbean and Asian populations have higher susceptibility and severity
Symptoms
- Butterfly (malar) rash across the cheeks and nose (classical but present in only 50%)
- Photosensitivity: rash or flare after sun exposure
- Joint pain and swelling (arthritis)
- Fatigue
- Oral ulcers
- Hair loss (alopecia)
- Serositis: pleurisy or pericarditis
- Kidney involvement (lupus nephritis): protein in urine, hypertension, oedema
- Neuropsychiatric manifestations: headache, seizures, psychosis
- Raynaud's phenomenon
- Blood count abnormalities: anaemia, low white cells, low platelets
When to see a doctor
See a doctor for unexplained butterfly rash, multiple joint pains in a young woman, recurrent miscarriages, or any combination of multi-organ symptoms. Lupus nephritis requires urgent treatment to prevent kidney failure.
Diagnosis
ANA (antinuclear antibody) positive in 95 to 99% — highly sensitive but not specific. Anti-dsDNA and anti-Smith antibodies are more specific. Complement levels (C3, C4) low in active disease. Full blood count, urine protein:creatinine ratio. Classification uses EULAR/ACR 2019 criteria.
Treatments
Hydroxychloroquine
An antimalarial drug that reduces flare frequency, protects against organ damage, and reduces cardiovascular risk. Should be used in almost all patients with SLE unless contraindicated. Annual ophthalmology checks needed.
NSAIDs and corticosteroids
NSAIDs for joint and pleuritic pain. Corticosteroids control acute flares. Long-term high-dose steroids cause significant harm; doses should be minimised using steroid-sparing agents.
Immunosuppressants
Mycophenolate, azathioprine, or cyclophosphamide for organ-threatening disease (nephritis, neuropsychiatric lupus). Methotrexate for skin and joint disease.
Belimumab
A biologic that blocks B-cell survival factor (BLyS/BAFF). Licensed for active seropositive SLE. Reduces flare rate and steroid requirements.
Anifrolumab
Targets the type I interferon receptor. Newly approved for moderate-to-severe SLE, with good evidence for skin and joint disease reduction.
Self-care and lifestyle
- Use high-factor (SPF 50) broad-spectrum sunscreen every day
- Wear sun-protective clothing and avoid peak sun hours
- Do not smoke (smoking worsens SLE and reduces hydroxychloroquine efficacy)
- Avoid oestrogen-containing contraception if antiphospholipid antibodies are present
Prevention
SLE cannot be prevented. Avoiding known triggers (sun exposure, smoking, certain drugs) may reduce flare frequency.