रोगपरिहारः · Roga Parihāra

In Dharmaśāstra literature, the Karmavipāka section deals mainly with the expiations that remove the sins responsible for various diseases. Diseases caused by wrong deeds are not cured by medicine alone unless the sin, their root, is removed. Medicines act on diseases that arise merely from the derangement of the three doṣas — vāta, pitta and kapha. Diseases that are the result of past deeds, and those produced by the doṣas and past deeds together, are cured with the help of prāyaścitta.

The history of an individual does not begin with a single birth. The current of karma, good or bad, follows the jīva through many births and shapes its condition. To relieve the suffering that is the fruit of past wrong actions, the ancient ṛṣis analysed its causes and laid down the means of removing them. When a tree is grown, only a small seed is sown; but undoing the effect of that seed is a great labour.

The word karmavipāka means the ripening of deeds. A deed, once done, does not itself persist, so it cannot directly be the cause of a disease. Rather, a wrong deed produces an unseen and lasting force called apūrva, which affects the person until it is exhausted by bearing its fruit or nullified by a suitable prāyaścitta.

Pūrvajanma. The Cārvākas, who accept only pratyakṣa pramāṇa, denied the other world. The Naiyāyikas answered them and established pretyabhāva (rebirth). In the first āhnika of the third adhyāya of the Nyāya-sūtras, Gautama refutes the objections:

पद्मादिषु प्रबोधसम्मीलनविकारवत् तद्विकारः (३.१.२०)
नोष्णशीतवर्षाकालनिमित्तत्वात् पञ्चात्मकविकाराणाम् (३.१.२१)
अयसोऽयस्कान्ताभिगमनवत् तदुपसर्पणम् (३.१.२३)
नान्यत्र प्रवृत्त्यभावात् (३.१.२४)

The opening and closing of the lotus has its own cause in the seasons; the magnet draws iron and not stone. No effect is seen without a cause, and so a newborn's first reaching for its mother's milk arises from desire carried over from earlier impressions (see Vātsyāyana's Bhāṣya). In the Ṛgveda, Vāmadeva says he knew the many births of the gods and had himself taken many bodies.

In the Vedic period, prāyaścittas rectified faults in sacrifices. By the Purāṇic period they had come to address actions of past births as well. When a disease did not yield to medicine, the sages recognised a hidden cause besides the doṣas — sin — and prescribed Karmavipāka prāyaścittas to wash it away. The Purāṇas, Smṛtis and Karmavipāka works lay down remedies such as kṛcchra, atikṛcchra and payovrata.