The Sun- life and light of our earth, has been a huge inspiration to human beings from the outset of his intellectual aspirations. Perspiring under the sun may have helped him from early days to simulate it into a therapy for his ailments. Ayurveda perceive sun as a symbol of heat, transformation and depletion. Similarly Svedana or sudation therapy is meant to heat up the body, transform the body toxins into evacuable forms and deplete excess fat, thus making the body lighter.
Svedana is practiced as a preparatory aspect of Panchakarma (five detoxification procedures) or as an independent therapy. Most involves applying hot vapour to a body part, or getting inside a steam chamber having retractable lids in lying down position.  Sudation is achieved with the help of steam made of hot Ayurvedic decoction flowing into the chamber.
The procedure is done for a few minutes daily, up to a maximum of seven days. The duration of treatment will vary according to the disease treated. Svedana is also done by applying heated medicated powder in bolus (choorna pinda sveda), heated sand filled in small bolus (Valuka sveda) and cooked medicinal leaves made into a bolus (pathra pinda sveda).
Svedana is considered to be the most frequently conducted procedure done at Ayurveda Panchakarma clinics. Market surveys reports that Svedana amounts to approximately 95% of total procedures carried out in a typical Ayurveda Panchakarma clinic.
How does it work?
In physics heat is energy. When heat is added to a substance, molecules move faster. Similarly in body, if energy flows into us we perceive it as heat, temperature rises. Svedana is transfer and regaining of vitality by directing a concentration of heat energy where it is deficient. Svedana is expected to provide optimum metabolic function, suppleness, skin complexion, relish for food and permeability of body vessels. It restores flexibility of joints from stiffness. In its role as a preparatory process for detoxification of the body by Panchakarma, it augments the flow of morbid elements from remote body parts to gastro-intestinal tract.
Efficacy studies
Clinical trials using the therapy in treating osteoarthritis has shown that it is effective in reducing pain and edema (Kshipra Rajoria et al, NIA, Jaipur). Clinical trial on Svedana using sand(Valuka sveda) in Rheumatoid arthritis showed significant improvement in biochemical mediators such as C-Reactive Protien, Rheumatoid Factor and anti-CCP(Cyclic citrulinated peptides) (Mishra Pramod Kumar Department of Kayachikitsa, Faculty of Ayurveda, IMS, BHU, Varanasi, India).
Is it safe?
Whole body heating is known to cause cardiovascular stress in healthy individuals. An increase of body temperature during Svedana will increases the cutaneous vascular and systemic conductance. Due to these effects on cardiac output, a Svedana procedure should preferably be avoided in cases where hemodynamic functions are affected because of pre-existing disease conditions. Hypothyroidism, congestive heart disease and cardiomyopathy are good examples. Patients who have suffered myocardial infarcts and ischemic heart disease should also avoid Svedana procedure according to studies (Sanjeev Rastogi, Francesco Chiappelli; AYU 2013).