fatigue AE SS, YH, MW NCIt: C3036; NCIt: C78416 CTCAE: E11098 (fatigue); CTCAE: E12709 (lethargy) lethargy AE HPO: HP_0003388 lethargy is sometimes reported as an extreme fatigue: http://the-difference-between.com/lethargy/fatigue they are sometimes regarded as synonyms: https://www.nlm.nih.gov/medlineplus/ency/article/003088.htm 10016256 SIDER: C0015672 WEB: http://en.wikipedia.org/wiki/Fatigue_%28medical%29 10024264 a behavior and neurological AE that has an outcome of fatigue, which is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles. Physical fatigue is the inability to continue functioning at the level of one's normal abilities. behavioral and neurological AE