I have had 5 rounds of chemotherapy for breast cancer and the incidences of feeling like I am going to black out are more frequent and last more days in the cycle than at the beginning of the treatments. My hgb. goes up and down each week and this doesn't seem to be related to it. When I am sitting I am OK. My BP is always normal at the office. Is this a normal side effect or should I be concerned? I am a 65 yr. old female with controlled high BP. Thank you, Kathy