Lupus is an autoimmune disease, which means your body attacks itself, and it’s not clear why. Lupus is a chronic disease that causes inflammation in one or more of your body’s systems. It can affect your joints, skin, kidneys, heart, lungs and brain. Lupus symptoms vary from person to person, but common symptoms include fatigue, joint pain and swelling, fevers and headaches. In some cases, it can also cause inflammation of the heart or lungs.