Despite the best HLA matching, the body may still not recognize the new kidney as part of itself. For this reason, people with kidney transplants must take certain drugs the rest of their lives. These drugs are called immunosuppressants, because they suppress the immune system to keep it from fighting the new organ. These drugs include azathioprine and cyclosporin A. Despite these drugs, some kidney transplants fail. When the body attacks the new organ as foreign, it is called rejection.
Immunosuppressant drugs pose dangers.
Although suppressing the immune system keeps it from noticing the foreign organ, it also keeps the immune system from noticing infections. As a result, the person can get sick more easily. These drugs also have many side effects. A new kidney does not cure diabetes, and the disease may damage the new kidney just as it did the original ones. But it took many years for the person's own kidneys to fail.