It is important to realize that just because ginkgo biloba (ginkgo) is a "natural" product, it is not necessarily free of side effects. Ginkgo biloba can cause serious side effects, such as seizures, internal bleeding, and allergic reactions. If you experience any of these serious side effects, you should seek immediate medical attention. However, not all side effects of ginkgo biloba are serious. Some side effects are merely bothersome, such as an upset stomach, dizziness, and nausea.
(For more information, click Ginkgo Biloba Side Effects. This eMedTV article provides an in-depth look at possible side effects of ginkgo biloba, including a list of which side effects require immediate medical attention.)