Ginseng, Garlic, Gingko, and Ginger are all helpful herbs, but all share the ability to interfere with allopathic "medicines", especially blood thinners, neurological drugs, and some heart medications. They all have properties which allow them to increase flow through barrier membranes as well.
Before thinking I'm anti-herbal, believe me, I'm about the farthest from it! Herbs are fabulous aids in healing. But, THERE IS NO SUCH THING AS A MIRACLE DRUG OR HERB.
Healing and health require cleansing out (and keeping out) toxins, plus adding pure fresh filtered water, fresh foods, exercise, and sleep. Herbs of various forms can aid in restoring balance and re-adding needed biochemicals and nutrients missing from food (we've almost killed our soils resulting in food that is not as nutrient dense as it could be.) Herbs also can help ease symptoms and speed healing, but they are not replacements for living a healthier life.
Herbs are supplements and as such can be dangerous, especially if misused or taken in large doses over long periods of time. Many herbs have adverse affects on allopathic "medicines" and should be well researched before taking. Garlic, for instance, crosses the brain blood barrier so efficiently that it, by itself, can cause slight drowsiness, slowed reaction times, and impaired judgment - especially in high dosages. Mixed with allopathic pharmaceuticals, it can be downright dangerous. For another example, aside from the four mentioned above, Saint John's Wort can be Very Dangerous for people taking prescribed neurological drugs. The list goes on and on.
Every individual should research carefully the herbs they're interested in, taking careful note of any possible side effects or interactions with allopathic "medicines" or even other herbs! It is also wise to give your body a rest period when taking ANY herbs. A good rule of thumb is one day off for every 2 or 3 days on and never going more than 2 weeks straight on any herb. Example: 2 weeks taking a medicinal dosage of an herb daily, take 4 to 7 days OFF the herb before starting up again. This not only allows your body a much needed rest period, it allows you the chance to find out how your body is assimilating and adjusting to the herb.
Being responsible for our own health is a serious responsiblity and should be taken thoughtfully. That said, have a safe and healthy exploration of the wonderful world of herbs!