Wonder what causes lupus? Lupus, an autoimmune disease, happens when the immune system attacks its tissues, causing inflammation, swelling, pain, and damage. The immune system's job is to fight foreign substances in the body, like germs and viruses. But in autoimmune diseases, the immune system is out of control. It attacks healthy tissues, not germs. Lupus symptoms vary, and early lupus symptoms include fatigue, joint pain, fever, and a lupus rash, especially after being in the sun. No one knows what causes lupus. Scientists think that people are born with the genes to develop lupus and that something brings on or "triggers" the disease and symptoms. However, a combination of genetics (heredity), environment, and hormones is involved.Doctors diagnose lupus by symptoms and blood tests. Lupus is not contagious but has a hereditary component, so family health information is important. Lupus occurs more frequently in women than it does in men, though it isn't clear why. Four types of lupus exist — systemic lupus erythematosus, discoid lupus erythematosus, drug-induced lupus erythematosus and neonatal lupus. Of these, systemic lupus erythematosus is the most common and serious form of lupus.