Svedana  Dravya has its main actions like Stambhaghna, Gauravaghna, Sītaghna and Sveda Kārakatva

स्तम्भगौरवशीतघ्नं स्वेदनं स्वेदकारकम्||

( Cha. Su 22/11)

Sedative effect

The sedative effect produced relieves the pain in area. This may be because of the increased blood supply which produces removal of waste products hence getting a good nourishment. Heat is also a counter irritant ie the thermal stimulus may effect the pain sensation as explained in pain gate theory of Melzack and Wall. This explains the effect of heat applied on the nerves. Vāta is the responsible factor for inducing pain in the body and the properties of Vāta and Svedana are exactly the opposite. Hence the heat can cause reduction in pain by reducing the swelling, removing the coldness at the site and causing perspiration.

Relieves Stiffness (Staṃbha)

Stiffness is a resultant of excess Sīta Guṇa. Vāyu by Rūkṣa Guṇa absorbs Snigdhatā which results in Staṃbha. Svedana by its Snigdha and Uṣṇa property relieves Staṃbha. Uṣṇa Guṇa of Svedana does Srotośuddhi and Āmapācana and relieves stiffness. Rise in temperature induces muscle relaxation and increases the efficiency of muscle action, as the increased blood supply ensure the optimum conditions for muscle contraction.

Relieves Coldness

This is mainly due to Uṣṇa Guṇa of Sveda. As a result of the increased metabolism, the output of waste products from the cells is increased. These include metabolites, which act on the walls of capillaries and arterioles causing dialation of these vessels. In addition, the heat has a direct effect on the blood vessels, causing vasodilatation, particularly in the superficial tissues where the heat is more. Stimulation of superficial nerve endings can also cause a reflex dilatation of the arterioles. As a result of the vasodilatation there is an increased flow of blood through the area, so that the coldness of body gets removed.

Relieves heaviness

Svedana relieves heaviness in the body. Heaviness is reduced due to Kapha Vilayana by Uṣṇa and Laghu Guṇa of Svedana.

Stimulation of sweat glands

Svedana promotes sweating. There is reflex stimulation of the sweat glands in the area exposed to the heat, resulting from the effect of the heat on the sensory nerve endings.  As the heated blood circulates throughout the body it affects the centres concerned with the regulation of temperature and there is increased activity of the sweat glands throughout the body

Relieves obstruction of channel

The Heat has a direct effect on the blood vessels, causing vasodilatation, particularly in the superficial tissues where the heat is more. Stimulation of superficial nerve endings can also cause a reflex dilatation of the arterioles. As a result of the vasodilatation there is an increased flow of blood through the area, so that the necessary oxygen and nutritive materials are supplied and waste products are removed. Thus channels get cleared. Svedana  Kaṛma   helps to dissolve Kapha which is in dense stage (Grathita) stuck to the channels firmly by its Uṣṇa, Tīkṣṇa Guṇa. Further it liquifies Kapha allowing it to move freely.

Agni dīpana

As Svedana  is Ushna Guṇa Pradhana, it stimulates Agni and hence does the Āma Pācana.

Tvak Mārdava

Mechanism of sweat involves the skin, where in hair follicles, the Mūla of Svedavaha Srotas are situated. Due to Sweating and excretion, skin becomes soft and pleasant.

स्निग्धस्य सूक्ष्मेष्वयनेषु लीनं स्वेदस्तु दोषं नयति द्रवत्वम्

(Cha. Si. 1/8)

Svedana helps to liquify the vitiated Dōṣas that have spread throughout the microchannels of the body.

Mode of action of Śodhanāṅga Sveda

स्नेहक्लिन्नाःकोष्ठगाधातुगावा
स्रोतोलीनायेचशाखास्थिसंस्थाः|
दोषाःस्वेदैस्तेद्रवीकृत्यकोष्ठं
नीताःसम्यक्शुद्धिभिर्निर्ह्रियन्ते|                            (A. H. Su 17/29)

The anointed Doṣas which were lodged at different regions of peripheral parts, gets liquefied by sudation therapy were brought back to the central part of the body for easy elimination by the appropriate Śodhana methods.