A book on popular remedy titled "Daitouruijuho" (『大同類聚方』) , edited in 808 in early stages of the Heian period, is the oldest book on the popular medical treatment in Japan (100 volumes in all). It is also the oldest government-designated pharmacopeia.
The 51st Emperor Heizei (774-824) apprehended that the Japanese popular remedy method was on the verge of collapse, caused by the inflows of Chinese medicine.
He ordered the leading powerful clans and old families, shrines to submit material on the ancient medical method.
Abeno Manao (安倍真直), Izumo Hirosada (出雲広貞) and others carried out the task to edit the collected materials.
The method of cure deafness with remedy is recorded in detail in the book.
For example, what is necessary is just to give her the medicine, when a
woman after the delivery faints, her complexion becomes red and
impossible to say a thing.
Moreover, when a person becomes deaf after serious illness, medicine is prepared for him to take.
A 6-year-old child faints and hardly speaks. Several days afterward, he
becomes mute, which can recover if the medicine is given to him.