I know, it is not going to help you a bit, but I want to share how it works in Germany and many other European countries. I happen to sometimes consult on managerial stuff in pharmaceutical circles in Europe, but I'm not a medical professional by any stretch of imagination.
Anyhow, in Germany there is something loosely translated as "traditional remedies", which are basically phyto-pharmaceuticals known for generations. If they match a few criteria, esp. clinical efficacy (ie. empirical proof, this is not homeopathy we are talking about), those are written down in a "book of remedies". Once written down in this book, the remedy can be produced by anyone. Most of them may only be sold in pharmacies and sometimes they are so potent and dangerous that they require prescriptions (Colchicine is easy to overdose, but does not require a prescription). By virtue of being public, your pharmacist could mix them up (most do not do this anymore), or they can be produced as generics -- and they are.
This sometimes creates weird situations. For example, there is a common stomach remedy best known under the trademark name "Iberogast". The traditional remedy is a concoction of nine herbs and written down as such. Now, a few decades ago independent studies showed that three of these nine herbs are basically contra-effective and should be removed. Doing that, however, creates a new remedy, which is not recorded in the book and therefore may not be produced freely.
The main producer of Iberogast, Bayer, went to great length to create a new, improved formula, with clinical trials and all that jazz. Obviously, Bayer has the exclusive rights to this improved formula before it can be written into the book of remedies again. It is selling it under the name of "Iberogast Advanced". You probably should prefer this "advanced" version, but you can still go to your pharmacist and get a "classic" concoction mixed up, or buy one of the generics.
Can you just buy the six herbs and combine them yourself?
Under American law, such a traditional (or innovative) remedy can be produced and sold by anyone. It would be an unregulated supplement instead of a regulated medicine. The effect is that doctors can't prescribe it.
Doctors are still free to tell you that you might be interested in independently obtaining and taking a supplement.
Anyhow, in Germany there is something loosely translated as "traditional remedies", which are basically phyto-pharmaceuticals known for generations. If they match a few criteria, esp. clinical efficacy (ie. empirical proof, this is not homeopathy we are talking about), those are written down in a "book of remedies". Once written down in this book, the remedy can be produced by anyone. Most of them may only be sold in pharmacies and sometimes they are so potent and dangerous that they require prescriptions (Colchicine is easy to overdose, but does not require a prescription). By virtue of being public, your pharmacist could mix them up (most do not do this anymore), or they can be produced as generics -- and they are.
This sometimes creates weird situations. For example, there is a common stomach remedy best known under the trademark name "Iberogast". The traditional remedy is a concoction of nine herbs and written down as such. Now, a few decades ago independent studies showed that three of these nine herbs are basically contra-effective and should be removed. Doing that, however, creates a new remedy, which is not recorded in the book and therefore may not be produced freely.
The main producer of Iberogast, Bayer, went to great length to create a new, improved formula, with clinical trials and all that jazz. Obviously, Bayer has the exclusive rights to this improved formula before it can be written into the book of remedies again. It is selling it under the name of "Iberogast Advanced". You probably should prefer this "advanced" version, but you can still go to your pharmacist and get a "classic" concoction mixed up, or buy one of the generics.