Virechana is the procedure by which the vitiated Doshas (mainly Pitta Pradhana) are eliminated through the anal route.
Virechana is considered to be the most effective way of eliminating the exaggerated Pitta Pradhana Tridosha from Panchyamanashaya (small intestine)
It is also highly preferable in Raktapradoshaja vikaras (Diseases caused due to vitiated blood), Mamsapradoshaja vikaras (Diseases caused due to poor  muscle tissues), Asthipradoshaja vikaras (Bone & joint disorders), Majjapradoshaja vikaras (Bone marrow disorders) & Shukrapradoshaja vikaras (Low libido and infertility).