Lupus is a chronic autoimmune disease that causes the immune system to attack the body's own tissue and organs, including the joints, kidneys, heart, lungs, brain, blood or skin. In an autoimmune disease, the body's immune system loses its ability to distinguish between foreign substances and its own cells and tissue. However, it is not infectious, or cancerous, and it is not associated with AIDS.
The mildest form of lupus consists of a red rash or change in skin color on the face, often in the shape of a butterfly across the nose and cheeks. Systemic lupus is more severe, accounting for 70 percent of all cases, in which inflammation in various tissues in the body occurs. This often leads to long-term damage to major organs, such as the lungs, kidneys, heart or brain. Symptoms include painful or swollen joints, frequent high fever, chest pain, swollen glands, fatigue, hair loss, pale or purple fingers or toes from cold or stress, sensitivity to the sun, low blood count, mouth sores, and unexplained seizures or kidney problems.
Scientists don't yet know what causes lupus, but they believe there is a genetic predisposition to the disease, compounded by environmental factors. Lupus may be triggered by infections, antibiotics, ultraviolet light, extreme stress, certain drugs and hormones. The latter might explain why lupus occurs more frequently in women than in men. Men are more likely to develop drug-induced lupus, triggered by drugs used to treat heart conditions more common in men.