What Is Systemic Lupus Erythematosus (SLE)?

Systemic lupus erythematosus (SLE) is an autoimmune disease that causes the immune system to attack its own healthy tissue around the body.1 SLE is the most common type of lupus — about 70 percent of people with lupus have SLE.2 Usually, when people talk about lupus, they’re referring to SLE.

How Is SLE Different from Other Types of Lupus?

There are four main types of lupus. Other than SLE, the other types of lupus are:2

  • Cutaneous lupus erythematosus (CLE) — a type of lupus that only affects the skin
  • Drug-induced lupus — a type of lupus caused by taking certain medications
  • Neonatal lupus — a rare type of lupus that affects newborn babies of women who have lupus

SLE differs from these types of lupus because it can affect any part of the body, not just the skin.2 Since the cause of SLE is complicated and largely unknown, the symptoms of SLE can’t be stopped by taking away the cause. In contrast, when the drug that causes drug-induced lupus is stopped, the symptoms of lupus usually go away after about six months.14 Additionally, SLE usually occurs in women aged 15 to 44 years, whereas neonatal lupus only occurs in infants.15

Systemic Lupus Erythematosus (SLE) Symptoms

SLE symptoms can vary from person to person and can change over time. SLE can affect any organ in the body, causing different symptoms.2

The symptoms of SLE are often not specific to lupus and can be similar to other diseases. Common symptoms of SLE include:2,3

  • Skin rashes
  • Arthritis (joint pain or swelling)
  • Swelling in feet or lower legs
  • Fatigue
  • Fever
  • Photosensitivity (sensitivity to the sun)
  • Dry eyes and dry mouth

People living with SLE may experience periods of more severe symptoms — called a flare — and periods of fewer symptoms — known as remission. Some people with SLE have frequent flares, while others may go months or years without a flare.1

SLE Complications

Inflammation in different parts of the body can cause more severe complications in some people, as follows:3

  • Kidney inflammation — also called lupus nephritis, can cause kidney damage that makes it harder for the body to filter the waste from the blood.4
  • Brain inflammation — can cause headaches, confusion, fatigue, and memory problems.5
  • Lung inflammation — can cause cough, chest pain, trouble breathing, and blood clots.6
  • Heart inflammation — can cause chest pain, an irregular heartbeat, and blood clots.7
  • Joint and muscle inflammation — can cause swollen, painful joints, muscle weakness, and pain.8
  • Digestive tract inflammation — can cause mouth sores, heartburn, diarrhea, and constipation.9

Causes of SLE

Researchers are still working to discover the cause of lupus. There isn’t just one thing that causes SLE. SLE probably develops as a response to a number of different factors, including genes, hormones, and the environment.10

Genetics and SLE

Genes are the blueprint of the body and are passed down from your parents. There are more than 50 genes associated with lupus. While these genes are more common in people with lupus, researchers haven’t found that any of these genes directly cause SLE.10

Hormones Related to SLE

Hormones help regulate many of the body’s functions. Researchers began investigating the connection between hormones, such as estrogen, and lupus. Lupus is more common in women who have higher levels of estrogen. Even though there is a link between estrogen and lupus, researchers haven’t yet proven that estrogen can cause lupus.10

Environmental Links to SLE

Researchers have also investigated if things in the environment can trigger lupus in people who are susceptible.

The most common environmental triggers include:10

  • Ultraviolet light from the sun
  • Some viral infections, such as the Epstein-Barr Virus (EBV)
  • Silica dust

Risk Factors for Developing SLE

Some people are more likely to develop lupus. The risk factors for SLE include:11,12

  • Female sex — 9 out of 10 people with lupus are women
  • Age between 15 and 45 years old — people are most commonly diagnosed during this time
  • Non-white race/ethnicity — SLE is more commonly diagnosed in people of color (including African Americans, Hispanics/Latinos, Asian Americans, Native Americans, Native Hawaiians, and Pacific Islanders)
  • Having a family member with lupus — people who have a family member with lupus have a 5 percent to 13 percent risk of also developing it

Diagnosing SLE

Diagnosing SLE can be difficult because the symptoms aren’t specific and can be different for everyone. Because of this, SLE is often diagnosed by a doctor who specializes in immune-related conditions called a rheumatologist.13

There isn’t one test to diagnose SLE. Doctors must use several factors, including symptoms, past medical history, family history, blood tests, and other laboratory tests to diagnose SLE.13