There are medications called cell growth factors (also called colony stimulating factors) that can be given along with chemo or radiation to prevent red blood counts from dropping. The growth factor that boosts production of red blood cells is epoetin or darbepoetin (brand names Procrit, Epogen, Aranesp). Growth factors can take between two and eight weeks to work, so they're not a solution for dramatic red blood cell loss. There's also a risk of side effects, so a patient's doctor will decide whether to prescribe cell growth factors based on her assessment of the patient's risk of developing a low red blood count.

Get as much information as you can from the doctor about the chemo regimen of the person you're caring for and the effect you can expect it to have on his red blood count. "Some drugs reduce the red blood cell count by 25 percent immediately; some drugs take a week before the count start to drop. Every drug and regimen is different," says Terry Anders, an oncology nurse at the Zangmeister Cancer Center in Columbus, Ohio. Because side effects include fluid retention and heart palpitations -- both of which can worsen heart conditions -- the doctor will take into account whether the patient has heart problems when deciding whether to prescribe Procrit or other growth factors. Other side effects include diarrhea, vomiting, fever, and upper respiratory infection. In addition, Procrit can cause shortness of breath and edema, so if the person you're caring for already has these problems, the doctor may be conservative about prescribing it.