I began taking a ginkgo supplement and soon developed distortion in my field of vision. It completely blocked my sight in parts of my visual field and covered it in pretty moving geometric patterns. There was no pain. The distortion gradually shrank and disappeared over about an hour. My vision returned to normal. I tossed the bottle of ginkgo and it didn't happen again, until years later when I bought another bottle of ginkgo thinking the first must have been tainted. Same thing. I only took a few of the pills before it happened. If I only take one now and then there is no problem.
