Fatigue

===Formal classification===
The [[World Health Organization]]'s [[ICD-11]] classification<ref name="ICD-11">{{Cite web|title=ICD-11 - Mortality and Morbidity Statistics {{!}} MG22 Fatigue|url=https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/1109546957|date=2019|website=World Health Organization|access-date=2023-04-25|archive-date=2018-08-01|archive-url=https://archive.today/20180801205234/https://icd.who.int/browse11/l-m/en%23/http://id.who.int/icd/entity/294762853#/http://id.who.int/icd/entity/1109546957|url-status=live}}</ref>
includes a category MG22 Fatigue (typically fatigue following exertion but sometimes may occur in the absence of such exertion as a symptom of health conditions), and many other categories where fatigue is mentioned as a secondary result of other factors.<ref>
* 8E49 Postviral fatigue syndrome
* QE84 Acute stress reaction, Combat fatigue
* 6A70-6A7Z Depressive disorders
* 07 Sleep-wake disorders
* FB32.5 Muscle strain or sprain, causing muscular fatigue
* NF01.3 Heat fatigue, transient
* MA82.Y Voice disturbances, causing voice fatigue
* BD1Z Heart failure, unspecified, causing myocardial fatigue
* JA65.Y Conditions predominantly related to pregnancy, causing fatigue which complicates pregnancy
* SD91 Fatigue consumption disorder, causing coughing, fever, diarrhea, chest pain etc.
* MG2A Ageing associated decline in intrinsic capacity, causing senile fatigue
* NF07.2 Exhaustion due to exposure
* NF01 Heat exhaustion
* 6C20 Bodily distress disorder.
[[ICD-11]]</ref> It does not include any fatigue-based psychiatric illness (unless it is accompanied by related psychiatric symptoms).<ref name="Desai2018">{{cite journal |last1=Desai |first1=Geetha |last2=Sagar |first2=Rajesh |last3=Chaturvedi |first3=Santosh K |title=Nosological journey of somatoform disorders: From briquet's syndrome to bodily distress disorder |journal=Indian Journal of Social Psychiatry |date=2018 |volume=34 |issue=5 |pages=29 |doi=10.4103/ijsp.ijsp_37_18 |doi-access=free }}</ref><ref name="pmid32701520">{{cite journal |last1=Basavarajappa |first1=Chethan |last2=Dahale |first2=Ajit Bhalchandra |last3=Desai |first3=Geetha |title=Evolution of bodily distress disorders |journal=Current Opinion in Psychiatry |date=September 2020 |volume=33 |issue=5 |pages=447–450 |doi=10.1097/YCO.0000000000000630 |pmid=32701520 |s2cid=220731306 }}</ref> 

[[DSM-5]] lists 'fatigue or loss of energy nearly every day' as one factor in diagnosing depression.<ref>{{Cite web|url=https://www.psycom.net/depression/major-depressive-disorder/dsm-5-depression-criteria|title=Depression Definition and DSM-5 Diagnostic Criteria|date=August 26, 2022|website=www.psycom.net|access-date=March 21, 2024|archive-date=February 13, 2024|archive-url=https://web.archive.org/web/20240213040922/https://www.psycom.net/depression/major-depressive-disorder/dsm-5-depression-criteria|url-status=live}}</ref>