Medically Unexplained Physical Symptoms

Medically unexplained physical symptoms (MUPS) or medically unexplained symptoms (MUS) are patient symptoms for which the treating physician, other healthcare providers, and research scientists have found no medical cause. The term does not necessarily imply that a physical cause does not exist, but rather notes that cause(s) for given symptoms are uncertain, unknown or disputed—there is no scientific consensus. A task force of the US National Institutes of Health states, "Medically unexplained syndromes (MUS) present the most common problems in medicine."

Estimates of primary care consultations with medically unexplained symptoms range from 15% to a high of 66% in specialty settings. Psychiatric co-morbidity is common, but symptoms may not be due exclusively to psychiatric factors and there may be a strong association between psychiatric morbidity and physical symptoms irrespective of whether they have a medical explanation or not. Association with depressive and anxiety disorders increases with the number of unexplained symptoms reported, but medically unexplained symptoms "as a whole" are not necessarily associated with depression and anxiety.

Physical symptoms have been associated with adverse psychosocial and functional outcome across different cultures, irrespective of etiology (either explained or unexplained). One use of the term MUS is in reference to the overlapping symptoms present in a variety of conditions such as chronic fatigue syndrome, fibromyalgia, multiple chemical sensitivity, somatoform disorder, and Gulf War Illness, which also share a significant overlap in treatment.