Some people claim that the reason herbs are not prescribed as drugs by licensed physicians is that the medical effectiveness of herbs is seriously in doubt  No drug can be offered for sale, however, unless it has regulatory-agency approval for medicinal use in specific illnesses or conditions  It costs about $200 million to get regulatory-agency approval for a drug, and only the holder of a patent can expect to recover such large expenses  Although methods of extracting particular substances from herbs can be patented, herbs themselves and their medicinal uses cannot be
Ttherefore, under the current system licensed physicians cannot recommend the medicinal use of herbs
some other substances, besides herbs, are not available as drugs because the illnesses they could effectively treat are too uncommon to allow those substances to be marketed profitably as drugs