The Chinese have been prescribing medicine for over 2000 years.
Now that's what I call experience!!
Obviously its a bad idea for your GF to be taking her Mums medicine , yet it may be a problem persuading her to stop..
Whats seems to be wrong with her? Has she been to see a western style doctor in the RP?
If you can get her to see a local respected Doc in her area perhaps they will best able to explain the dangers of taking Inay`s meds..
Thats about the best I can suggest.