Is it safe to take 5 hour flight with hemoglobin level of 9.9? I m a young breast cancer survivor (diagnosed at 37 years old and now 43 years old) and finished treatment (other than tamoxifen ) 5 years ago. I ve been chronically anemic since start of chemo . Since January I have had extremely heavy bleeding & heavy bleeding between cycles. Uterine biopsy negative for malignancy. I started period again 3 day ago and already lost 22 tablespoons of blood fluid as measured by menstrual cup. (9.9 hemoglobin level was accurate as of 1o days ago). Anyway, my childhood friend passed away from breast cancer an I want to fly home for her funeral in 5 days. My oncologist knows tis but didnt mention possible increased problem if I fly. (She did give me option of transfusion but I declined for now.) My sister in law who is a MD ( psychiatrist) told me too dangerous to fly,