DravyaGun the science of dravyas and their gunas. The subject is one of the major parts of the Ayurvedic medicine system the ancient science of life and primarily deals with the substances having Medicinal potential. Major sources of this ancient knowledge are Charak Samhita, Sushrut Samhita, Vaghbhat, and Nighantus. As per the Acharya Charak Ayurveda is science that deals with hitakari (beneficial) and ahit Kari (detrimental) dravyas for life , the statement highlights the importance of Dravyaguna in Ayurveda.
Without dravyas any treatment is not possible and hence ayurvedic hierarchy displays it just after the Bhishak i.e. physician. This subject can be said as the basis of all the Ayurvedic medications because it is in Dravyaguna we learn the effect of a dravya on the Doshas and Prakritis, by reviewing their ras gun virya vipak i.e. Ayurvedic pharmacology and hence estimate their potency as a medicine. The whole practice of extracting the drugs from its source, its pharmacognosy, preservation, and consumption is dealt with in the study of Dravyaguna.
Dravyaguna also elucidates the importance of ahaar in chikitsa i.e. importance of food in the treatment. Hereto the science also takes into account the sources of dravyas i.e. majorly plants and thus review their morphology, anatomy, physiology and conservation as well. Dravyaguna can be compared to the present day's study of pharmacology and Materia Medica.