Lupus is a condition in which the body's immune system attacks its own tissues and organs. This is called an autoimmune condition. Lupus causes swelling and irritation, called inflammation, that may affect joints, skin, kidneys, blood cells, brain, heart and lungs. Lupus can be hard to diagnose because its symptoms often are like those of other illnesses. A common sign of lupus is a facial rash that looks like butterfly wings across both cheeks. The rash gets worse when in the sun. Many but not all people with lupus get this rash. Some people are born more likely to get lupus. Infections, certain medicines or even sunlight can trigger the condition. There's no cure for lupus, but treatments can help manage symptoms.