A history of frequent illnesses may also contribute to the development of this disorder. In some cases, individuals with factitious disorder are accustomed to actually being sick, and thus return to their previous state to recapture what they once considered the "norm". Another cause is a history of close contact with someone (a friend or family member) who had a severe or chronic condition. The patients found themselves subconsciously envious of the attention said relation received, and felt that they themselves faded into the background. Thus medical attention makes them feel glamorous and special. Diagnosis
Criteria for diagnosis include intentionally fabricating to produce physical or psychological signs or symptoms and the absence of any other mental disorder. Motivation for their behavior must be to assume the "sick" role, and they do not act sick for personal gain as in the case of malingering sentiments. When the individual applies this pretended sickness to a dependent, for example, a child, it is often referred to as "factitious disorder by proxy".The DSM-5 differentiates among two types:

Factitious disorder imposed on self (Munchausen syndrome)
Factitious disorder imposed on another (Munchausen syndrome by proxy), defined as: When an individual falsifies illness in another, whether that be a child, pet, or older adult. Factitious disorder imposed on self
Factitious disorder imposed on self, previously called Munchausen syndrome, or factitious disorder with predominantly physical signs and symptoms, has specified symptoms. Factitious disorder symptoms may seem exaggerated; individuals undergo major surgery repeatedly, and they "hospital jump" or migrate to avoid detection.
A factitious disorder is a condition in which a person, without a malingering motive, acts as if they have an illness by deliberately producing, feigning, or exaggerating symptoms, purely to attain (for themselves or for another) a patients role. People with a factitious disorder may produce symptoms by contaminating urine samples, taking hallucinogens, injecting fecal material to produce abscesses, and similar behaviour. Factitious disorder imposed on self (also called Munchausen syndrome) was for some time the umbrella term for all such disorders. Factitious disorder imposed on another (also called Munchausen syndrome by proxy, Munchausen by proxy, or factitious disorder by proxy) is a condition in which a person deliberately produces, feigns, or exaggerates the symptoms of someone in their care. In either case, the perpetrators motive is to perpetrate factitious disorders, either as a patient or by proxy as a caregiver, in order to attain (for themselves or for another) a patients role. Malingering differs fundamentally from factitious disorders in that the malingerer simulates illness intending to obtain a material benefit or avoid an obligation or responsibility. Somatic symptom disorders, though also diagnoses of exclusion, are characterized by physical complaints that are not produced intentionally. Causes
The causes are mostly unknown. One possible cause is trauma but the rest is still going through a testing process. It is also been suspected that it might be hereditary, like depression. There are still many possible causes for this disorder which havent been defined yet.These individuals may be trying to reenact unresolved issues with their parents.