How low does red blood count need to go before the doctor recommends treatment?

This is a very individual decision, and the doctor will make it based more on symptoms (such as fatigue or shortness of breath) than on a particular number. It's likely the doctor will take a wait-and-watch attitude for as long as possible before recommending medication or a transfusion, because she's hoping the red blood count will rise on its own. Also, keep in mind that red blood counts aren't likely to drop dramatically right after chemo; it usually takes one to two weeks for the blood count to reach what doctors call the nadir, the point at which it drops to its lowest point. Cutoff rates vary according to different labs, but if hemoglobin drops below eight, most doctors will recommend either growth factors or a transfusion.