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A diagram of a human torso labelled with the most common symptoms of an acute HIV infection
Signs including (enlarged liver and spleen), and symptoms (including headache, and vomiting) of acute HIV infection.

Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showing on a medical scan. A symptom is something out of the ordinary that is experienced by an individual such as feeling feverish, a headache or other pain or pains in the body.[1][2]

A medical sign is an objective indication of a disease, injury, or abnormal physiological state that may be detected during a physical examination.[3] These signs are visible or otherwise detectable such as a rash or bruise. Medical signs assist in arriving at an accurate diagnosis. Examples of signs include elevated blood pressure, nail clubbing of the fingernails or toenails, staggering gait, and arcus senilis and arcus juvenilis of the eyes. A sign is distinguished from an indication which is a specific reason for using a particular treatment.

A symptom is something felt or experienced, such as pain or dizziness. Signs and symptoms are not mutually exclusive, for example a subjective feeling of fever can be noted as sign by using a thermometer that registers a high reading.[4]

Signs and symptoms are often nonspecific, but some combinations can be suggestive of certain diagnoses, helping to narrow down what may be wrong. A particular set of characteristic signs and symptoms that may be associated with a disorder is known as a syndrome. In cases where the underlying cause is known the syndrome is named as for example Down syndrome and Noonan syndrome. Other syndromes such as acute coronary syndrome may have a number of possible causes. In other cases when known as cardinal signs and symptoms they are specific even to the point of being pathognomonic. A cardinal sign or cardinal symptom can also refer to the major sign or symptom of a disease.[5] Signs and symptoms are also applied to physiological states outside the context of disease, as for example when referring to the signs and symptoms of pregnancy, or the symptoms of dehydration.

Signs versus symptoms

Signs are different from experienced symptoms. A sign of a disorder is something that may be observed by another or detected during a medical examination or procedure.[3] For example high blood pressure may be noted as a sign during an examination for which there have been no reported symptoms. A symptom is something experienced and reportable by a person such as a headache or fatigue. Signs and symptoms may overlap, such as a bloody nose, which the individual experiences as unusual (symptom) and which others observe (sign).


Signs and symptoms may be mild or severe, brief or longer-lasting when they may become reduced (remission), or then recur (relapse or recrudescence) known as a flare-up. A flare-up may show more severe symptoms.[6]Constitutional symptoms are those related to the systemic effects of a disease such as fever, malaise, and weight loss. They affect the entire body rather than a specific part.

The terms "chief complaint", "presenting symptom", "iatrotropic symptom", or "presenting complaint" are used to describe the initial concern when an individual seeks medical help. The symptom that ultimately leads to a diagnosis is called a cardinal symptom.

Non-specific signs and symptoms include self-reported symptoms that do not indicate a specific disease process or involve an isolated body system. For example, chronic fatigue is a feature of many medical conditions, and may be either a primary or secondary symptom. Sometimes signs and symptoms can be characteristic of a particular disease and are known as a syndrome. Noonan syndrome for example, has a diagnostic set of unique facial and musculoskeletal features.[7]

Sensory symptoms can also be described as positive symptoms, or as negative symptoms depending on whether the symptom is abnormally present such as tingling or itchiness, or abnormally absent such as loss of smell. The following terms are used for negative symptoms - hypoesthesia is a partial loss of sensitivity to moderate stimuli, such as pressure, touch, warmth, cold. Anesthesia is the complete loss of sensitivity to stronger stimuli, such as pinprick. Hypoalgesia (analgesia) is loss of sensation to painful stimuli.[8] Symptoms are also grouped in to negative and positive for some mental disorders such as schizophrenia.[9] Positive symptoms are those that are present in the disorder and are not normally experienced by most individuals and reflects an excess or distortion of normal functions.[10] Examples are hallucinations, delusions, and bizarre behavior. Negative symptoms are functions that are normally found but that are diminished or absent such as apathy and anhedonia.[10]

Signs and symptoms may be classified by the type of inference that may be made from their presence, for example:

"[If the patient's facial] appearance may be described thus: the nose sharp, the eyes sunken, the temples fallen in, the ears cold and drawn in and their lobes distorted, the skin of the face hard, stretched and dry, and the colour of the face pale or dusky.... and if there is no improvement within [a prescribed period of time], it must be realized that this sign portends death."[12]
  • Anamnestic signs (from anamn?stikós, , "able to recall to mind"): signs that (taking into account the current state of a patient's body), indicate the past existence of a certain disease or condition.[11]:81 Anamnestic signs always point to the past. (As King (1982) explains, whenever we see a man walking with a particular gait, with one arm paralysed in a particular way, we say "This man has had a stroke"; and, if we see a woman in her late 50s with one arm distorted in a particular way, we say "She had polio as a child".[11]:81)
  • Diagnostic signs (from diagn?stikós, , "able to distinguish"): signs that lead to the recognition and identification of a disease (i.e., they indicate the name of the disease).[11]:81
  • Pathognomonic signs (from pathognomonikós, , "skilled in diagnosis", derived from páthos, , "suffering, disease", and gn?mon, , "judge, indicator"): the particular signs whose presence indicates with certainty, that a particular disease is present.[13] They are an intensification of a diagnostic sign. An example is the palmar xanthomata seen on the hands of people with hyperlipoproteinaemia.
"Symptoms become signs when they permit inference. Ordinarily, one single symptom by itself--such as pain or swelling, or discoloration, or bloody discharge--would not permit any specific inference, but when signs and symptoms occur in clusters and form a pattern, then the aggregate might point to a particular disease. The pathognomonic sign, however, does not need any other manifestation to lead the physician to the correct diagnosis. It constitutes a one-to-one relationship--the sign and the disease are uniquely related. The pathognomonic sign was the "clincher", the datum that established the diagnosis unequivocally."[11]:100


The CDC lists various diseases by their signs and symptoms such as for measles which includes a high fever, conjunctivitis, and cough, followed a few days later by the measles rash.[16]

Some signs and symptoms occur in a wide range of disease processes, whereas other symptoms are fairly specific for a narrow range. For example, a sudden loss of sight in one eye has a significantly smaller number of possible causes than nausea does. Some symptoms can be misleading as a result of referred pain, where for example a pain in the right shoulder may be due to an inflamed gallbladder and not to presumed muscle strain.



A symptom (from Greek , "accident, misfortune, that which befalls",[17] from , "I befall", from - "together, with" and , "I fall") is a departure from normal function or feeling. Symptomatology (also called semiology) is a branch of medicine dealing with the signs and symptoms of a disease.[18][19][20] This study also includes the indications of a disease.[21] It was first described as semiotics by Henry Stubbe in 1670 a term now used for the study of sign communication.

Prior to the nineteenth century there was little difference in the powers of observation between physician and patient. Most medical practice was conducted as a co-operative interaction between the physician and patient; this was gradually replaced by a "monolithic consensus of opinion imposed from within the community of medical investigators".[22][23] Whilst each noticed much the same things, the physician had a more informed interpretation of those things: "the physicians knew what the findings meant and the layman did not".[11]:82

Advances in the 19th century

Input from the patient was gradually reduced from the medical interaction[22][23][24] due to significant technological advances such as:

  • The 1808 introduction of the percussion technique, "the process through which "the physician can assess the state of the underlying lung by sensing the character of vibrations by gentle taps on the chest wall [something which] greatly facilitated the diagnosis of pneumonia and other respiratory diseases".[25] The techniques, which had been first described by the Viennese physician Leopold Auenbrugger (1722–1809) in 1761, became far more widely known following the publication of Jean-Nicolas Corvisart's (French) translation of Auenbrugger's (Latin) work in 1808.
  • The 1819 introduction by René Laennec (1781–1826) of the technique of auscultation (using a stethoscope to listen to the circulatory and respiratory functions of the body). Laennec's publication was translated into English, 1821–1834, by John Forbes.
  • The 1846 introduction by surgeon John Hutchinson (1811–1861) of the spirometer, an apparatus for assessing the mechanical properties of the lungs via measurements of forced exhalation and forced inhalation. (The recorded lung volumes and air flow rates are used to distinguish between restrictive disease (in which the lung volumes are decreased: e.g., cystic fibrosis) and obstructive diseases (in which the lung volume is normal but the air flow rate is impeded; e.g., emphysema).)
  • The 1851 invention by Hermann von Helmholtz (1821–1894) of the ophthalmoscope, which allowed physicians to examine the inside of the human eye.
  • The (c. 1870) immediate widespread clinical use of Sir Thomas Clifford Allbutt's (1836-1925) six-inch (rather than twelve-inch) pocket clinical thermometer, which he had devised in 1867.[26]
  • The 1882 introduction of bacterial cultures by Robert Koch, initially for tuberculosis, being the first laboratory test to confirm bacterial infections.
  • The 1895 clinical use of X-rays which began almost immediately after they had been discovered that year by Wilhelm Conrad Röntgen (1845–1923).
  • The 1896 introduction of the sphygmomanometer, designed by Scipione Riva-Rocci (1863–1937), to measure blood pressure.

Changes of relationship between physicians and patients

The introduction of the techniques of percussion and auscultation into medical practice altered the relationship between physician and patient in a significant way, specifically because these techniques relied almost entirely upon the physician listening to the sounds of the patient's body.

Not only did this development reduce the patient's capacity to observe and contribute to the process of diagnosis, it also meant that the patient was often instructed to stop talking, and remain silent.

As these changes took place in medical practice, it was increasingly necessary to uniquely identify data that were accessible only to the physician, and to be able to differentiate those observations from others that were also available to the patient, and it just seemed natural to use "signs" for the class of physician-specific data, and "symptoms" for the class of observations available to the patient.

King proposes a more advanced notion; namely, that a sign is something that has meaning, regardless of whether it is observed by the physician or reported by the patient:

The belief that a symptom is a subjective report of the patient, while a sign is something that the physician elicits, is a 20th-century product that contravenes the usage of two thousand years of medicine. In practice, now as always, the physician makes his judgments from the information that he gathers. The modern usage of signs and symptoms emphasizes merely the source of the information, which is not really too important. Far more important is the use that the information serves. If the data, however derived, lead to some inferences and go beyond themselves, those data are signs. If, however, the data remain as mere observations without interpretation, they are symptoms, regardless of their source. Symptoms become signs when they lead to an interpretation. The distinction between information and inference underlies all medical thinking and should be preserved.[11]:89

As tests

In some senses, the process of diagnosis is a matter of assessing the likelihood that a given condition is present. Haemoptysis (coughing up blood) for example is much more likely to be caused by a respiratory disease than by a broken toe. Each question asked in taking the medical history can narrow down the view of the cause of the symptom, testing and building up their hypotheses as they go along.

Examination, which is essentially looking for clinical signs, allows the medical practitioner to see if there is evidence in the patient's body to support their hypotheses about the disease that might be present.

A patient who has given a good story to support a diagnosis of tuberculosis might be found, on examination, to show signs that lead the practitioner away from that diagnosis and more towards sarcoidosis, for example. Examination for signs tests the practitioner's hypotheses, and each time a sign is found that supports a given diagnosis, that diagnosis becomes more likely.

Special tests (blood tests, radiology, scans, a biopsy, etc.) also allow a hypothesis to be tested. These special tests are also said to show signs in a clinical sense. Again, a test can be considered pathognonomic for a given disease, but in that case the test is generally said to be "diagnostic" of that disease rather than pathognonomic. An example would be a history of a fall from a height, followed by a lot of pain in the leg. The signs (a swollen, tender, distorted lower leg) are only very strongly suggestive of a fracture; it might not actually be broken, and even if it is, the particular kind of fracture and its degree of dislocation need to be known, so the practitioner orders an x-ray--and, for example, if the x-ray were to show a fractured tibia, the film would be diagnostic of the fracture.

Examples of signs

See also


  1. ^ "Beyond Intuition: Quantifying and Understanding the Signs and Symptoms of Fever". 5 October 2017. Retrieved 2021.
  2. ^ "Symptoms and self-help guides by body part | NHS inform". Retrieved 2021.
  3. ^ a b "Definition of SIGN".
  4. ^ Marie T. O'Toole, ed., Mosby's Medical Dictionary, 9th ed. (St. Louis, MO: Elsevier/Mosby, 2013), Kindle loc. 154641. ISBN 9780323085410
  5. ^ Basu, S; Sahi, PK (July 2017). "Malaria: An Update". Indian journal of pediatrics. 84 (7): 521-528. doi:10.1007/s12098-017-2332-2. PMID 28357581.
  6. ^ Shiel, William C. Jr. (20 June 2019). "Definition of Flare". MedicineNet. Retrieved 2019.
  7. ^ Romano, Alicia A.; Allanson, Judith E.; Dahlgren, Jovanna; et al. (October 2010). "Noonan syndrome: clinical features, diagnosis, and management guidelines". Pediatrics. 126 (4): 746-759. doi:10.1542/peds.2009-3207. ISSN 1098-4275. PMID 20876176. S2CID 11297756.
  8. ^ Harrison's Principles of Internal Medicine, 19th edition, Chapter 31: Numbness, Tingling, and Sensory Loss
  9. ^ "Mental Health: a Report from the Surgeon General". 1999. Archived from the original on 11 January 2012. Retrieved 2011.
  10. ^ a b Understanding Psychosis Archived 2012-12-25 at the Wayback Machine, Mental Health Illness of Australia.
  11. ^ a b c d e f g King, Lester S. (1982). Medical Thinking: A Historical Preface. Princeton, NJ: Princeton University Press. ISBN 0-691-08297-9.
  12. ^ Chadwick, J. & Mann, W.N.(trans.) (1978). Hippocratic writings. Harmondsworth, UK: Penguin. pp. 170-71. ISBN 0-14-044451-3.CS1 maint: multiple names: authors list (link)
  13. ^ "Definition of PATHOGNOMONIC".
  14. ^ Freire, MO; Van Dyke, TE (October 2013). "Natural resolution of inflammation". Periodontology 2000. 63 (1): 149-64. doi:10.1111/prd.12034. PMC 4022040. PMID 23931059.
  15. ^ Archived 2006-04-06 at the Wayback Machine
  16. ^ "Measles Signs and Symptoms". Centers for Disease Control and Prevention. 5 November 2020. Retrieved 2020.
  17. ^ "Sumptoma, Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Pursues". Retrieved 2011.
  18. ^ The British Medical Association (BMA) (2002). Illustrated Medical Dictionary. A Dorling Kindersley Book. p. 406. ISBN 978-0-75-133383-1.
  19. ^ "Definition of SYMPTOMATOLOGY". Retrieved 2021.
  20. ^ "Definition of SEMIOLOGY". Retrieved 2021.
  21. ^ David A. Bedworth, Albert E. Bedworth (2010). The Dictionary of Health Education. Oxford University Press. p. 484. ISBN 978-0-19-534259-8. Archived from the original on 9 May 2018.
  22. ^ a b Jewson, N.D., "Medical Knowledge and the Patronage System in 18th Century England Archived 7 March 2009 at the Wayback Machine", Sociology, Vol. 8, No. 3 (1974), pp. 369-85.
  23. ^ a b Jewson, N.D., "The Disappearance of the Sick Man from Medical Cosmology, 1770–1870 Archived 16 March 2009 at the Wayback Machine", Sociology, Vol. 10, No. 2, (1976), pp. 225-44.
  24. ^ Tsouyopoulos N (1988). "The mind-body problem in medicine (the crisis of medical anthropology and its historical preconditions)". Hist Philos Life Sci. 10 Suppl: 55-74. PMID 3413276.
  25. ^ Weatherall, D. (1996). Science and the Quiet Art: The Role of Medical Research in Health Care. New York: W.W. Norton & Company. p. 46. ISBN 0-393-31564-9.
  26. ^ Allbutt, T.C., "Medical Thermometry", British and Foreign Medico-Chirurgical Review, Vol. 45, No. 90, (April 1870), pp. 429-41; Vol. 46, No. 91, (July 1870), pp. 144-56.

External links

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