Objective: To analyze the composition principles of prescriptions for emesis in Prescription of Traditional Chinese Medicine Dictionary. Method: The prescriptions for emesis in Prescription of Traditional Chinese Medicine Dictionary were selected

and traditional Chinese medicine inheritance support system (TCMISS) V2.5 was used to enter information and build the database. The commonly used herbs

combination principles

core combinations and new combinations in the prescriptions for emesis were analyzed with data mining methods

such as association rules

improved mutual information method

complex system entropy clustering and unsupervised hierarchical clustering. Result: Total 174 herbs were involved in the 305 prescriptions for emesis

including

49 herbs with the frequency of more than 10 times

forty-five commonly used herb pairs and combinations

fifty-eight potential core combinations and nine newly developed prescriptions. Conclusion: The composition principles of prescriptions for emesis in Prescription of Traditional Chinese Medicine Dictionary are defined

which provides references for clinical medication and new drug development. The commonly used herbs are mainly citrus

pinellia

ginger and some tonics.