Vasti is the most important of the Panchakarma therapies in Ayurveda. It involves the introduction of herbal oils and decoctions into the colon through the rectum. Of the three humours, only Vata, concentrated mainly in the large intestine (colon), has the power of mobility. When its movement is affected, the functions of the other two humours, viz., Pitta and Kapha are also adversely affected.

In Sanskrit, Vasti means bladder. Traditionally a special device consisting of a small tube and bladder was used to administer the medicine. The urinary bladders of cows and buffaloes were preferred for this and that is how the therapy obtained its name. These days modern enema equipment is used.

In Nirooha or Asthapana Vasti, herbal decoctions are used. Medicated oils are used in Anuvasana or Sneha Vasti. Oil and sweat therapies precede Vasti. The appropriate time for performing Vasti is one or two hours before noon. Vasti is never performed immediately after meals. The Vasti fluids are allowed to remain in the colon for a specific period for proper absorption. When it is let out, toxins from the Dhatus are expelled along with the faecal matter. 

Vasti is not recommended for patients suffering from diarrhoea, asthma, piles or diabetes. As in the case of Vamana, after Vasti, a strict diet regimen has to be followed.