An old employer flew us directly from weeks at sea level to work at 10,000 feet. Major risk of altitude sickness and even embolism, so we were required to take either a commercial altitude sickness medicine or ginkgo biloba. You can imagine the choice I took.
What would be harder to foresee was the number of people who switched after a day or two from the commercial altitude sickness medicine to the ginkgo. Originally, people opted about evenly between the two options; but as the ginkgo people quickly adapted to altitude and the drug-choosers adapted more slowly and experienced more side effects, about half of them soon switched to gingko biloba as well.
This natural compound is well-regarded as being able to dilate the blood vessels and thereby improve bloodflow throughout the body, including to the brain, until the cardiovascular system can produce enough new red blood cells to address the reduced oxygen levels available at elevation. I was convinced!