‏While herbs and dietary supplements can be purchased over-the-counter (OTC) and may be labeled "all-natural", this does not always mean they are safe. Many of these products, just like prescription drugs, may have serious drug interactions.
‏For example, St. John's Wort, CoenzymeQ10, and even melatonin can interact with medicines like antidepressants, blood thinners like warfarin or even alcohol. These interactions can be just as serious as prescription medicines.
‏Because there's not always formal studies, some drug interactions with herbal products may not be known. Also, remember that herbal supplements are not subject to FDA review and have not usually been tested in clinical studies to prove their effectiveness or safety.
‏Your pharmacist can give you a better idea of what drug interactions may occur with any herbal or herbal dietary supplements you may be taking. Advice from your health care provider is your best option in preventing serious health effects from any drug interaction.