A psychosomatic illness is one with physical manifestations but without any known or identifiable physical cause. On a basic level, virtually everyone will scratch their head if you tell them a story about headlice, and a large number will feel nauseated or worried about themselves (what was in that last meal I ate?) when hearing about someone else's food poisoning experience.
The mind has a powerful influence over the body, and it is quite possible for a person to feel extremely physically ill without any real physical reason, especially if they suffer from an anxiety disorder. Worrying over the physical symptoms exacerbates them, leading the patient to the doctor for reassurance that there isn't actually anything seriously wrong with their health. A psychosomatic illness will generally improve or disappear after this reassurance is delivered, e.g., by negative test results.
Some doctors automatically dismiss the symptoms of any patient who has been diagnosed with an anxiety disorder on these grounds without any further treatment other than verbal reassurance. If the illness is genuinely psychosomatic this may be sufficient, but it can also be a very dangerous thing to do as many serious illnesses, such as heart disease and cancer, have initial vague symptoms. On the other hand, treating a psychosomatic illness as a physical illness can have very serious consequences as well. Not only will the patient not get better, he or she could even get worse from wrongly prescibed drugs or other treatments.
There were times when almost any illnesses suffered by women were ascribed to hysteria, while anything men suffered from was not, since it was believed men did not suffer from hysteria. This view has changed since World War I, when men started to return from the front with what was called "shell-shock syndrome". There was no apparent physical cause of the illness, but a psychological cause was dismissed aforehand, since it was "known" that men did not suffer from such illnesses. Only after a long struggle by some prominent psychiatrists it became accepted that men could also suffer from hysterical illnesses, which are now called psychosomatic.
