Rasayana treatment involves mobilizing body nourishments to through out the body. Rasayana therapy is used to maintain optimum body performance at a micro level by providing nourishment to the tissues, repairing damaged tissues and facilitating the growth of new cells. Rasayana literally means the travel (ayana) of nourishments (rasa). It also expels accumulated toxins from the body. In other words, it is making the person younger.
Charaka acharya in his script, Charaka Samhita states that Rasayana is something that promotes vigour in the healthy. According to him the results of rasayana chikitsa are long life, sharp memory, increased intelligence, freedom from diseases, youthfulness, excellence in complexion, sweet voice, good physical strength, better use of five senses, and acceptance by other people.
Chyavanaprasham (also spelt — chyavanaprash, chyavanaprasam, chyavanvaprasa, chyavanapras) and Lehya (lehyam) come in rasayana therapy. Chyavanaprasam from different companies are available in different medical shops, grocery stores, pharmacists, etc. Chyavanaprasham is especially recommended to students, and persons with cough, and weak physique.
Rasayana chikitsa or rasayana therapy is best associated with panchakarma therapy, where the rasayanas or lehyas revitalizes the body cells.
However, rasayanas are available for independent use also. You can find rasayanas can be used without undergoing panchakarma therapy.