Usually, your immune system defends your body from many of the things that can harm it. But when the system doesn't work right, it can attack healthy tissues and organs. This is an autoimmune disease. One part of your immune system is a protein called tumor necrosis factor, also known as TNF, which is produced naturally by the body's immune system. But in certain autoimmune diseases, some people produce too much TNF. This often leads to inflammation. HUMIRA is a medication called a TNF blocker. It works by binding to TNF molecules and blocking them from attaching to and attacking healthy cells. In this way, HUMIRA helps reduce the damaging effects of excess TNF. Remember no treatment can stop your body's overproduction of TNF, but a medication like HUMIRA can help reduce its effects.