It is gingko biloba, I have gone on and off of it, but the dizziness and tiredness do return. I do not like being dizzy very much! I think it also had a tiny anti-depressant effect in it, so it is a double yay. It improves circulation, this is what it does. I went to the pulmonologist and he does this oxygen test and yes, it did really improve my level by one point 99) but still it works. It is not addictive, it is not dangerous, it is safe and effective. You just need a good brand, that was why I mentioned what I used. I would also tell my doctor I was using it. They don't care anyway, but I would make them note it in my chart. Medical doctors are not big fans of any supplments unless they give it, or its medicine in my expierence. I got lucky because the ent was smart and believed in both and this was his idea, and a great one! I also do use a sublingual vitamin b complex as well. I have really read a lot about this stuff, I am not a expert but I just want to live and be happy.