http://www.medicalnewstoday.com/articles/177446.php"Restrictions should be placed on the use of Ginkgo biloba (G. biloba) - a top-selling herbal remedy - because of growing scientific evidence that Ginkgo may increase the risk of seizures in people with epilepsy and could reduce the effectiveness of anti-seizure drugs, a new report concludes. The article appears in ACS' monthly Journal of Natural Products. It also suggests that Ginkgo may have harmful effects in other people after eating raw or roasted Ginkgo seed or drinking tea prepared from Ginkgo leaves.
Eckhard Leistner and Christel Drewke note that consumers use pills, teas, and other products prepared from leaves of the Ginkgo tree to treat a wide array of health problems. Those include Alzheimer's disease and other memory loss, clinical depression, headache, irritable bladder, alcohol abuse, blockages in blood vessels, poor concentration, and dizziness. Scientific concern focuses mainly on one chemical compound in the herb. It is a potentially toxic material known as ginkgotoxin.
..."Link to the review itself:
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/np9005019-----------------
Yes, more research is necessary, but side effects are not the sole domain of big pharma, so noting the possible side effects of "natural" products is also necessary.