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The term ‘hetu’ means a cause or etiological factor. Understanding the cause of the disease is crucial for complete knowledge of pathogenesis and treatment. Eradication or removal of the cause is the primary treatment of any abnormal condition. It helps in the prevention and recurrence of diseases, too. (SAT-C.60)[1]
The current healthcare system focuses on finding out a pathogenic micro-organism that causes diseases. Ayurveda, on the contrary, emphasizes the lacunae or defects in biological systems (kha -vaigunya) that occurred due to various reasons including, improper diet and lifestyle. The defense mechanism or immunity is vital to preserving health and prevent disease. The long-term exposure of weak causes or short-term exposure of potent causes can adversely affect the body channels. This gives a chance to the micro-organisms to overpower immunity, spread their toxins, and cause diseases. In the case of non-communicable diseases, the endogenous causes can cause damage. This article describes the etiology, various types of causes, and their importance in medical practice.

Section/Chapter/topic Nidana / Hetu
Authors Deole Y.S., Anagha S.
Reviewer and Editor Basisht G.
Affiliations Charak Samhita Research, Training and Development Centre, I.T.& R.A., Jamnagar, India
Correspondence email carakasamhita@gmail.com
Publisher Charak Samhita Research, Training and Development Centre, I.T.R.A., Jamnagar, India
Date of first publication: July 10, 2021
DOI 10.47468/CSNE.2021.e01.s09.065

Etymology and derivation

The word ‘hetu’ is derived from the Sanskrit word root ‘hi’ by adding the suffix ‘tun’. It means to cause, reason, object, motive etc.[2]


  • Karanam: It implies first cause. (SAT-C.64)
  • Nimittam: It means omen or prognostic feature (shakuna).( SAT-C.61)
  • Ayatanam: It means the site of lesion as a cause of disease. Ayatana means the site which provides shelter.( SAT-C.62)
  • Karta: It means the perpetrator or active and dominant cause of disease. (SAT-C.63)
  • Pratyaya: It means a demonstrating cause. It is used in terms of faith also.(SAT-C.65)
  • Samuthanam: It means the origin or progress of a disease that indicates etiopathology. (SAT-C.66) [Cha. Sa. Nidana Sthana 1/3]
  • Nidana: It means diagnosis. Nidana is the first among five tools for complete knowledge of disease (nidana panchaka). Nidana is often synonymously used to denote cause (hetu) and diagnosis. It also depicts the importance of cause in clinical practice.

Contextual meanings

  • The knowledge of etiology/causative factor of health and disease is an important component of the three fundamental components (trisutra) of knowledge of Ayurveda.[Cha. Sa. Sutra Sthana 1/24]
  • Hetu means the reason for the increase and decrease of anything. Similarity (samanya) is the reason for the increase (vriddhi). The dis-similarity (vishesha) is the reason for the decrease (hrasa/kshaya).[Cha. Sa. Sutra Sthana 1/44]
  • Hetu is a reason for the existence of something. The existence of life or consciousness (chetana) in a body is due to the presence of soul(atma)[Cha. Sa. Sutra Sthana 29/4]
  • Hetu is the source or cause of the origin of anything. [Cha. Sa. Sharira Sthana 5/8] Manifestation of diseases and sufferings on earth made ancient rishis to search for remedies. It led to the evolution of Ayurveda.[Cha. Sa. Sutra Sthana 1/6 and 136]
  • The reasoning or logical inference to know a medical condition is an important quality of a physician for good clinical practice. [Cha. Sa. Sutra Sthana 2/36]
  • Hetu is the cause or means/instrument for knowledge. It includes direct perception (pratyaksha), inference (anumana ), traditional testimony (aitihya) and analogy (aupamya). It is important to know the truth (tattva) employing these reasons. [Cha. Sa. Vimana Sthana 8/33]
  • It is one of the ten means of knowledge for a physician. ‘Karana’ means the one who does the action, he is the cause and doer. [Cha. Sa. Vimana Sthana 8/69]


The hetu are classified in various categories for better understanding.

Two types of causes (dwividha hetu)

I. As per the origin of disease:

a) Direct causes (utpadaka hetu): Etiological factors that directly cause disease by the accumulation of dosha. Example: dietetic, behavioral, psychological, accident, poisons etc.

b) Supportive or indirect causes (vyanjaka hetu): These are indirect or supportive to pathogenesis. For example, the seasonal variations or time of the day (early morning, midday, evening, midnight) are supportive causes. These indirectly help in increasing pathogenesis and stimulate the progression of a disease.

II.As per the source of causes:

a) External causes (bahya hetu): External causes include alterations in diet, lifestyle, and seasonal influences.

b) Internal causes (abhyantara hetu): Internal causes disequilibrium of functions of dosha, dhatu, mala, agni and indriya.

III. As per the site of cause:

a) Somatic cause (sharirika hetu): These causes lead to disturbances in the anatomy and physiology of the body.

b) Psychological cause (manasika hetu): These causes lead to disturbances in mental functions.

IV. As per clinical observations:

a) Aggravating factors (anupashaya) b) Relieving factors (upashaya). [Cha. Sa. Sutra Sthana 12/7 and 16]

V. As per epidemiological classification:

a) Common factors (sadharana karana): These factors are commonly shared by all individuals in society. These are observed in conditions affecting large population like epidemics, pandemics. Example: air (vayu), water (jala), geographical habitat (desha), season (kaala).

b) Individual specific factors (asadharna karana): These are specific to the person. Example: specific diet, life style etc. [Chakrapani, Cha. Sa. Vimana Sthana 3]

Three-fold classification (trividha hetu)

The three fundamental causes of any disease are as below:

a) Improper union of sense organs with their objects (asatmya indriyartha samyoga)

b) Intellectual error (prajnaparadha)

c) Time factor(kaala) [Cha. Sa. Nidana Sthana 1/3]

The causes influencing pathogenesis are categorized as below:

a) Dosha specific causes (dosha hetu): These include factors that aggravate dosha. For example, day time sleep caused aggravation of kapha dosha.

b) Disease specific causes (vyadhi hetu): These are factors that cause a disease. For example, repeated use of hot and cold things at same time (sheetoshnaviparyaya) is a specific cause of skin diseases (kushtha).

c) Dosha and disease specific causes (ubhaya hetu): These are factors that aggravate dosha and cause specific disease. For example, excess consumption of sweet, unctuous and heavy diet is the cause of kapha dushti (dosha hetu), as well as for kapha dosha dominant disorders (vyadhi hetu) like sthaulya (obesity) and madhumeha (diabetes)

Fourfold classification (hetu chatushtayam)

Proper, excessive, inadequate and impaired contact of sense organs with objects are four causes of diseases . [Cha. Sa. Sutra Sthana 8/30]

As per exposure to cause and course of pathogenesis, there are four types: [M. N. 1/5, madhukosha]

a) Immediate or acute causative factor (sannikrishta nidana): The potent cause directly leads to acute condition due to sudden aggravation of dosha. For example, excessive consumption of dry (ruksha) food items acutely cause vata aggravation and predominant disorders.

b) Delayed acting / chronic causative factor (viprakrishta nidana): These are distant causative factors, comparatively less influential in causing an acute disease. For example, the accumulation of kapha dosha during the early winter season (hemanta ritu) causes diseases in the spring season (vasanta ritu). These factors cause the gradual progression of a disease.

As per the capability in producing diseases [M. N. 1/5, madhukosha]

c) Dominant cause (pradhanaika hetu): This is a potent and primarily dominant cause of disease. These factors produce acute aggravation of dosha. E.g. poison.

d) Non- dominant cause (vyabhichari hetu): It is a weak cause. These factors cannot independently cause disease in the absence of favorable condition in the body.

Importance in diagnosis

The diagnosis of a disease depends on the identification of its cause (hetu). Detailed clinical history and examination can reveal the cause. Direct perception (pratyaksha), inference (anumana), authentic guidelines (aptopadesha/aitihya) and analogy (aupamya) are tools to know a disease. [Cha. Sa. Vimana Sthana 8/33]

Importance in preservation of health and prevention:

Avoiding the intellectual errors (prajnaparadha), control over one’s senses, retrospective cognizance , current and proper orientation of habitat, time and oneself are preventive measure for endogenous and exogenous diseases. [A. Hr. Suta Sthana 4/33]

Knowledge of dosha specific and disease specific causes help to prevent and manage that disease. This builds the stronger defence mechanism, important to preserve and promote health.

Importance in management of disease:

The management of a disease starts with proper identification and eradication of the causative factors.[ Su. Sa. Uttara Tantra 1/25]

The treatment modalities related to causes are classified as:

a) Opposite to the nature causative factor (hetu viparita)

b) Opposite to the nature of disease (vyadhi viparita)

c) Special treatment which is similar to cause (tadarthakari) [Su. Sa. Uttara Tantra 38/296, Dalhana]

The management protocol of every disease includes the diet, regimens and drugs with opposite qualities of particular cause. [Cha. Sa. Nidana Sthana 1/10]

E.g. in case of jwara (fever) due to excessive exhaustion and aggravation of vata, meat soup (mamsa rasa) is prescribed for restoring the equilibrium.

In case of aggravation of kapha dosha due to day sleep (divaswapna), awakening during night time (ratri jagarana) is advisable.

In case of fever caused by increase of kapha having cold (sheeta) property, drugs like Zingiber officinale(shunthi) having hot(ushna) property should be given. [ Cha. Sa. Nidana Sthana 1/10, chakrapani]

Contemporary approach and current researches

In the epidemiological literature, multiple definitions of causation are observed.[3] Causes are conditions that play essential part in producing the occurrence of disease.[4]

  • Necessary causes: A necessary cause is a condition without which the effect cannot occur. For example, HIV infection is a necessary cause of AIDS.[5]
  • Sufficient cause: A sufficient cause guarantees that its effect will occur; when the cause is present, the effect must occur.[6]
  • Sufficient-component cause: A sufficient-component cause is made up of several components. None of the components is sufficient to cause disease on its own. However, all components can cumulatively make up a sufficient cause.[7]
  • Probabilistic cause: It increases the probability of its effect occurring.[8]
  • Counterfactual cause: It makes a difference in the outcome (or the probability of the outcome) when present, compared with when it is absent, while all else is held constant.[9]

Hetu Kosha

A profound database of all etiological factors described in Charak Samhita, Sushruta Samhita, Ashtanga Hridaya and Ashtanga Samgraha is prepared under the heading of ‘Triskandha kosha’. This research project was conducted at Tilak Maharashtra Vidyapeetha, Pune, Maharashtra, India. The first part of this database is known as ‘Hetu kosha’. It includes nearly 3200 pages in print form. Ayuta Nidana is a diagnostic software developed by the team based on this database. It is helpful to Ayurveda physicians, researchers as a handy tool to search causative factors in a patient and diagnose.[10]

Theses done

1. Gujarathi Ritesh A (2004): Conceptual and applied aspects of Hrasaheturvisheshascha in the context of sthaulya, Department of Basic principles, IPGT &RA, Jamnagar.

2. Ashok Bhinshnoi (2018): Concept of Dukha hetavah in Brihattrayi w.s.r to Chittodvega(anxiety) and its management with Saraswatachoorna and diet and lifestyle modifications, Department of Basic principles, IPGT &RA, Jamnagar.

More information

  1. Jwara Nidana

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  1. National AYUSH Morbidity and Standardized Terminologies Electronic Portal by Ministry of AYUSH Available on http://namstp.ayush.gov.in/#/sat
  2. Jha Srujan. Amarkosha online application
  3. M Parascandola, D L Weed, Causation in epidemiology, J Epidemiol Community Health 2001;55:905–912.
  4. Krieger N. Epidemiology and the web of causation: has anyone seen the spider? Soc Sci Med 1994;39:887–903
  5. Charlton BG. Attribution of causation in epidemiology:chain or mosaic? J Clin Epidemiol 1996;49:105–7.
  6. Rothman KJ. Causes. Am J Epidemiol 1976;104:587–92
  7. Rothman K, Greenland S. Modern epidemiology. 2nd ed. Philadelphia: Lippincott Williams and Wilkins, 1998.
  8. Olsen J. Causes and prevention. Scand J Soc Med 1991;19:1–6.
  9. Maldonado G, Greenland, S. Estimating causal e Vects. [abstract]. Presented at the Society for Epidemiologic Research 31st Annual Meeting, Chicago, Illinois, June, 1998. Am J Epidemiol 1998;147:S80.
  10. Available from http://www.tmv.edu.in/pdf/Ayurved/Triskandha%20Kosha%20Project.pdf cited on 08/07/2021