structural:expansion
Principles and terminology

The central theoretical ideas of ayurveda show parallels with Samkhya and Vaisheshika philosophies, as well as with Buddhism and Jainism. Balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness. For example, to suppress sneezing is said to potentially give rise to shoulder pain. However, people are also cautioned to stay within the limits of reasonable balance and measure when following nature's urges. For example, emphasis is placed on moderation of food intake, sleep, and sexual intercourse.

According to ayurveda, the human body is composed of tissues (dhatus), waste (malas), and humeral biomaterials (doshas). The seven dhatus are chyle (rasa), blood (rakta), muscles (māmsa), fat (meda), bone (asthi), marrow (majja), and semen (shukra). Like the medicine of classical antiquity, the classic treatises of ayurveda divided bodily substances into five classical elements (panchamahabhuta) viz. earth, water, fire, air and ether. There are also twenty gunas (qualities or characteristics) which are considered to be inherent in all matter. These are organized in ten pairs: heavy/light, cold/hot, unctuous/dry, dull/sharp, stable/mobile, soft/hard, non-slimy/slimy, smooth/coarse, minute/gross, and viscous/liquid.

The three postulated elemental bodily humours, the doshas or tridosha, are vata (air, which some modern authors equate with the nervous system), pitta (bile, fire, equated by some with enzymes), and kapha (phlegm, or earth and water, equated by some with mucus). Contemporary critics assert that doshas are not real, but are a fictional concept. The humours (doshas) may also affect mental health. Each dosha has particular attributes and roles within the body and mind; the natural predominance of one or more doshas thus explains a person's physical constitution (prakriti) and personality. Ayurvedic tradition holds that imbalance among the bodily and mental doshas is a major etiologic component of disease. One ayurvedic view is that the doshas are balanced when they are equal to each other, while another view is that each human possesses a unique combination of the doshas which define this person's temperament and characteristics. In either case, it says that each person should modulate their behavior or environment to increase or decrease the doshas and maintain their natural state. Practitioners of ayurveda must determine an individual's bodily and mental dosha makeup, as certain prakriti are said to predispose one to particular diseases. For example, a person who is thin, shy, excitable, has a pronounced Adam's apple, and enjoys esoteric knowledge is likely vata prakriti and therefore more susceptible to conditions such as flatulence, stuttering, and rheumatism. Deranged vata is also associated with certain mental disorders due to excited or excess vayu (gas), although the ayurvedic text Charaka Samhita also attributes "insanity" (unmada) to cold food and possession by the ghost of a sinful Brahman (brahmarakshasa).

Ama (a Sanskrit word meaning "uncooked" or "undigested") is used to refer to the concept of anything that exists in a state of incomplete transformation. With regards to oral hygiene, it is claimed to be a toxic byproduct generated by improper or incomplete digestion. The concept has no equivalent in standard medicine.

In medieval taxonomies of the Sanskrit knowledge systems, ayurveda is assigned a place as a subsidiary Veda (upaveda). Some medicinal plant names from the Atharvaveda and other Vedas can be found in subsequent ayurveda literature. Some other school of thoughts considers 'ayurveda' as the ' Fifth Veda '. The earliest recorded theoretical statements about the canonical models of disease in ayurveda occur in the earliest Buddhist Canon.