Four Kinds of Diseases According to Ayurveda
The three somatic humors that govern the human system according to Ayurveda, namely Vata, Pitta and Kapha, in their state of equilibrium are called Tridhatus. These humors have a tendency to get vitiated and hence they are also known as Tridoshas. When vitiated due to various reasons, their equilibrium is also disrupted and makes the body susceptible to illnesses.
Diseases are of four main types such as Agantakam (diseases caused by external reasons), Shariram or Nijam (physical), Manasam (psychological) and Swabhavikam (natural or instinctive).
External (Agantakam) causes can be anything that ranges from poisoning through snake, insect bites, through food, a cut in the body with a sharp tool or a heavy blow etc that make the system yield to melodies. Classical texts even speak of a curse or an evil spell causing diseases.
Improper diet regimen and unhealthy life style are enough reasons to invite Nijam rogas or illness that originate from inside. Strong feelings like sorrow, anger, fear, depression, irritableness, lust etc in its excessive state can cause diseases. Stress felt due to unhealthy competitions may also cause illnesses. Their reasons come under Manasam (psychological) types.
Diseases caused by Swabhvika or natural reasons are hunger and/or thirst, decrepitude suffered in old age and imbecility. These are rather states of derangements of the body from its otherwise natural well being than be called as illnesses. Old seers termed it diseases in the sense that these states cause torments which may afflict the spirit that dwells within.