have not been able to donate blood at red cross due to high hematocrit levels. Finally got a therapeutic phlebotomy and now my levels are below 50%. Before the phlebotomy, level was about 56% and increasing upwards. About 2-3 months before getting a handle on high RBCs, I had some typical side effects of high hematocrit including frequent head aches (every day for 2 months--same time in the evening every day) and pretty bad shortness of breath. Also, 2 flights of stairs and I gasping for air. Even walking for more than a few miles would trigger breathlessness and strain on my lungs. And no, I am not obese or even slightly overweight or out of shape.. Anyway, I guess my point is, if you have high red blood cell count, get it taken care of as people with high hematocrit not only suffer the side effects mentioned above, but are also more susceptible to blood clots which can cause heart attack or stroke.