<unk> s are physical ailments (such as pain, nausea, depression, dizziness) or concerns for which no adequate medical explanation has been found.<unk> s are physical symptoms that seem as if they are part of a general medical condition. However, no general medical condition, other mental disorder, or substance is present. 
The complaints are serious enough to cause significant emotional distress and impairment of social and/or occupational functioning.
A diagnosis of a<unk>  implies that psychological factors are a large contributor to the symptoms' onset, severity and duration. It is important to note that<unk> s are not the result of conscious malingering or factitious disorders.
In psychology, a<unk>  is a mental disorder characterized by physical symptoms that suggest physical illness or injury – symptoms that cannot be explained fully by a general medical condition, direct effect of a substance, or attributable to another mental disorder (e.g. panic disorder). The symptoms that result from a<unk>  are due to mental factors. In people who have a<unk> , medical test results are either normal or do not explain the person's symptoms. Patients with this disorder often become worried about their health because the doctors are unable to find a cause for their health problems. This causes severe stress, due to preoccupations with the disorder that portrays an exaggerated belief about the severity of the disorder. Symptoms are sometimes similar to those of other illnesses and may last for several years. Usually, the symptoms begin appearing during adolescence, and patients are diagnosed before the age of 30 years. Symptoms may occur across cultures and gender.  Other common symptoms include anxiety and depression. In order for an individual to be diagnosed with<unk> , they must have recurring somatic complaints for several continuous years.<unk> s are not the result of conscious malingering (fabricating or exaggerating symptoms for secondary motives) or factitious disorders (deliberately producing, feigning, or exaggerating symptoms) – sufferers perceive their plight as real. Additionally, a<unk>  should not be confused with the more specific diagnosis of a somatization disorder.
Mental disorders are treated separately from physiological or neurological disorders.<unk>  is difficult to diagnose and treat since doing so requires psychiatrists to work with neurologists on patients with this disorder. Those that do not pass the diagnostic criteria for a<unk>  but still present physical symptoms are usually referred to as having "somatic preoccupation".
Somatoform disorder
Somatization disorder
Somatic symptom disorder
Malingering
Factitious disorder
Substance-related disorder
Tic disorder
Psychopathy