The foundation of Ayurveda is based on eight branches (Astanga Ayurveda) and in those one of the divisions is Agadh Tantra. According to Ayurveda classic reference, the detail description about the visha (poision) , its classification and examination, disease caused by it, different treatment principles, preventive measures of poision etc are described under the study of toxin or Agadhtantra.
The word Agadhtantra is derived from the combination of two words- Agada and Tantra.
Agada- The word again is formed by combination of Aa+Gada. Gada refers to disease, discomfort, pain, poision, or morbid conditions produced by any types of poison that are inhaled, absorbed, applied , injected or developed within the body.
Agada means the medicament which are used as antidotes to combat these morbid conditions.
Tantra means the science through which the positive health of an individual is preserved.
As we talk about visha (poison or toxin) in this tantra(subject); Let us know about visha. The visha word is derived from the root ‘Vish’ by having ‘Ka’ proportion which means to encompass or to get fully pervaded or to get occupied. Thus the one which pervade the whole body immediately after ingestion is called as visha.
Definition according to Ayurveda- The substance immediately after entering into the body cause the vitiation of the healthy dhatus or killing of the healthy person is defined as visha.
Definition according to modern- A poison is a substance which when administered, inhaled or ingested is capable of acting deleteriously on the human body. Thus almost anything is poison. There is really no boundary between a medicine and a poison, for a medicine in a toxic dose is poison and a poison in a small dose may be a medicine.
Properties of poison according to Ayurveda – The properties of poison(Visha) is same as the properties of (Alcohol)Madhya and opposite to that of Ojus. According to Aacharya Charak, they are a. Light (Laghu) b.Rough (Rukshya) c. Quick acting (Aashu) d. Non-slimy (Vishada) e. Quickly absorbed (vyavahi) f. Sharp (Tikshna) g. Depressant (Vikaasi) h. Minute (Sukshma) i.Undefinable taste (Anirdeshya rasa).
Sushruta mentioned same of the properties of the poison as like Charak but in the place of anirdesya rasa he mentioned apaaki.