The U.S. Food and Drug Administration is ordering manufacturers of some immunosuppressant drugs used in kidney transplants to change their labeling.

The FDA said the updated labels must reflect an increased risk of infections.

The required label changes affect drugs used to help prevent rejection of transplanted organs. The drugs are Rapamune (sirolimus), Sandimmune (cyclosporine), and three generic drugs, Neoral (cyclosporine modified), Cellcept (mycophenolate mofetil) and Myfortic (mycophenolic acid).

The FDA said it's requiring the changes based on its review of reported adverse events.

"The labeling changes must reflect the reported increased risk for opportunistic infections, including activation of latent viral infections," the federal agency said in a statement. "These include BK virus-associated nephropathy, which can mainly affect kidney transplant patients. Such infections may lead to serious outcomes, including kidney graft loss."

Officials said such information about the increased risk for opportunistic infections already is included in the labeling of the immunosuppressive drug Prograf (tacrolimus).