Doctors prescribing anemia drugs for patients with kidney disease and cancer were urged by the Food and Drug Administration (FDA) on Friday to carefully dispense of these drugs due to an increased risk of death and other serious problems, such as blood clots, strokes, and heart attacks in patients with chronic kidney failure and rapid tumor growth in patients with head and neck cancer who receive doses higher than recommended.

The potentially harmful drugs, sold under than brand names Procrit, Epogen, and Aranesp, are genetically engineered versions of a natural protein, called erythropoietin that increases the number of red blood cells. The drugs, with combined 2006 U.S. sales of $10 billion, are commonly used for patients with certain forms of kidney disease and for those receiving chemotherapy for cancer.

The FDA is adding warnings to the drugs’ labels that will strongly instruct doctors to use the lowest possible dose needed to help patients avoid blood transfusions.

The FDA will also take a close look at how the drugs are marketed, including claims the drugs can improve the quality of life.

A meeting of FDA officials to further discuss this issue, believed to stem from drug overuse by dialysis centers and oncologists who make more money by using more of the drugs. is scheduled for May 10. Recommendations could lead to additional revisions of the drugs’ labels.