First, we know far more about the adverse effects of drugs than we do about the adverse effects of “natural” substances.  In simple terms, if you take a medication for some ailment, as a pharmacist I will be able to tell you what the chances are that it could harm you and what side effects to look out for.  If you take an herb, I probably won’t be able to tell you with any certainty if it can harm you or if it is safe to use.  A considerable amount of research on herbs & nutraceuticals has been done in recent years, but our body of knowledge is still quite limited when it comes their actual safety and effectiveness, especially when compared to what we know about standard pharmaceutical medications. 

The other difference between pharmaceutical drugs and products marketed as “natural,” is the level of purity (i.e. does the product have in it what it is supposed to).  Pharmaceutical manufacturers must adhere to very strict standards.  If a medication is labeled as having 10 mg of an active ingredient, it will have 10 mg of that specific substance in it (plus or minus a very, very small amount due to the manufacturing process).  Some herbal products, on the other hand, have been found to contain only a fraction or none-at-all of the stated ingredient(s).  Sometimes they even contain ingredients not listed on the label. 

That said, herbs can be useful -- camomile can help settle an upset stomach, ginger helps with nausea, cranberry juice helps a urinary tract infection, and on and on.  But I cringe when I hear people say that herbs are safer than pharmaceutical drugs, or that herbs can't hurt you. They have side effects just like drugs, and some of them can be deadly.  Please becareful when deciding whether or not to use some herbal or nutraceutical product, you might make the problem you are trying to treat worse, or something else could go wrong with you.  And the same holds true with drugs.  Remember this, aspirin is a derivative of white willow bark, a naturally substance.  It has been around for over 100 years, it has been used by countless numbers of people, it alleviates pain and inflammation, and can help keep the cardiovascular system "healthy."  Overall, it is a pretty safe and effective drug, and we know a tremendous amount about it.  It's cheap and available to everyone.  But it can also cause ulcers in your stomach and "thin" your blood to such a point that if you were seriously injured you may run the risk of bleeding to death.  If such a simple and widely used medication can have a "dark side," so can anything else that you put into your body. 

Becarful.  Ask your physician and pharmacist lots of questions.  And most of all, be critical of the information you hear and read about anything you take, be it a drug or an herb, vitamin or nutraceutical. 

An excellent resource for learning about the use and side effects of herbs and nutraceuticals is the Natural Medicines Comprehensive Database  which is a book and companion web site.  The web site is the gold standard for evidence-based, clinical information on natural medicines.  It is the most complete and up-to-date reference available.  The main site is designed for the medical professional, but a separate site is available for the consumer/patient.