The Vedic corpus gives us a good number of hymns devoted to healthy living and longevity. The rejuvenation, healing and regeneration of dhatus plus scope of eternal transformation are seen in these Vedic hymns. These concepts of rejuvenation, longevity and immortality are transformed to Rasayana chikista of Astanga Ayurveda.
Many people interpret this branch as drug therapy. But it includes a stipulated code of conduct for controlling one's senses, special procedure practiced in the form of rejuvenative recipes, dietary regimen etc.
Rasa means the essence, here it stands for the essence of food we consume. Ayana means channels that transport this essence. The proper nourishment of our body is made possible only by proper functioning of these ayanas or channels that facilitate the movement and proper formation Rasa. The Rasayana drugs and the lifestyle improve these two aspects and helps to consider the factor that causes ageing process.

Classification:

A: As per the scope of use:
1. Kamya Rasayana - Promoter of normal health
Pranakamya - (Promoter of life's vitality and longevity)
Medhakamya - (Promoter of Higher mental faculty)
Srikamy - (Promoter of complexion and luster)

B: As per the scope of use:
2. Naimittika Rasayana - (Promoter of specific vitality in specific diseases)
Vatatpika Rasayana - (Without severe restriction, outer regimen)
Kutipravesika Rasayana - (Indoor Regimen, with severe restrictions)

C: As per contents of Rasayana are classified into three.
2. Naimittika Rasayana - (Promoter of specific vitality in specific diseases)
Ausadha Rasayana - (Drug Rasayana)
Ajasrika Rasayana - (Dietary Rasayana)
Acara Rasayana - (Special health promoting conduct and behavior.)

Vatatapika Rasayana
This is the routine procedure for administering Rasayana. The patient is not subjected to rigorous procedures. He remains in the society exposed to normal air, sun etc., and continues his normal work while undergoing the therapy.
Kutpraveshika Rasayana
Timing of administering Rasayana for the promotive purpose should be taken into account. This works only when it is used in early or middleage - 'Purvavayasai madhyeva'. It is advisable to select Rasayana suitable for different age groups in relevance to the rate of ageing described by Acharyas. They precisely state that an individual looses one of the ten important impacts of like processes every decade. Hence in respective decade, one should select such a Rasayana that can supplement the specific deficiency.

Decade of Life
Loss of impact/ Desired effect
Desirable Rasayana
1-10
Balya
Vata, Svarna
11-20
Vrddhi
Bala Kasmari
21-30
Chavi
Lanha, Amalaki
31-40
Medha
Shankuphusphi
41-50
Tvak
Jyotismathi
51-60
Arsti
Jyothismathi
61-70
Sukra
Tmagupta,Asvagandha
71-80
Vikrama Buddhi
Rasayana may
81-90
Vikrama Buddhi
not be

 

The concept of Rasayana has greater appeal to man, especially in the present world order. The judicious use of Rasayana drugs in Cancer treatment gives better prognosis in Cancer and AIDS treatment. Concept of Medhya Rasayana is to be used in detail to cope with new challenges like Alzheimer's disease, Parkinson's disease etc. Naimittika Rasayana or specific rasayana usage postulated by Sushrutha was very popular among traditional Vaidhyas of Kerala. This includes judicious selection of Rasayana drug, preparing the drug, and making the patient receive the treatment. Many diseases, like Coronary heart disease, Psoriasis, Diabetes mellitus, Motor neuron disease were intervened by traditional practitioners by this method. But due to various reasons this method is waning from the physicians except in some parts of Kerala and Tamil Nadu.

In a nutshell Rasayana Chikitsa or Rasayana therapy of Ayurveda is a very comprehensive discipline which introduces a hither to new concept of nutrition and with its relevance to qualities of dhatus, longevity, immunity or Bala, and mental competence and ability.

Agada tantra

This branch is very developed in Kerala, mainly studied and practiced by the princes, landlords and other affluent group of people for charity. This deals mainly with toxicology, and the practitioners of this school give free treatment to patients even today. Gada means disease and Agada means free from disease. This branch deals mainly with snake and other poisons; at the same time it also deals with diseases produced by allergic conditions and other auto-immune conditions.


Salakya Chikitsa (ENT and eye diseases)

Vajeekarana Chikitsa(Aphrodisiac therapy)