Used for two differ. ent things. St. Johns Wort is a mild antidepressant and works to calm the nervous system, whereas ginkgo biloba is a mental stimulant. So you wouldn't want to use both together or it may negate each others effects. Speak to your doctor to determine which one you may need now to help with symptoms that are more prevalent. Do you want to be more anxious, or more calm? Two different feelings.