An illness that occurs when the immune system attacks healthy tissues and organs.

Systemic lupus erythematosus is a long-lasting, known as chronic, illness that can affect many parts of the body. These can include joints, skin, kidneys, blood cells, brain, heart and lungs.

Symptoms can come on quickly or slowly. They can get worse for a while, then get better, which is called a flare. A common sign is a rash over the cheeks and nose in the shape of a butterfly. But not everyone gets the rash.

Treatment for systemic lupus erythematosus depends on symptoms. Medicines include pain relievers, medicines used to treat malaria, steroids, biologics and medicines that lower immune system responses.