Selena Gomez recently made headlines by ending her world tour early due to side effects from Lupus. Lupus is a chronic auto-immune disease which causes the immune system to erroneously attack health connective tissue throughout the body. Lupus causes skin rashes, muscle and bone issues, gastrointestinal problems, depression, heart and lung impairment and issues with reproduction, blood circulation and mental health. Selena Gomez revealed a year ago that she had undergone chemotherapy to treat the chronic autoimmune disease—chemotherapy drugs can reduce immune system activity but do have severe side effects.