Factitious fever (FF) is a false disease that can be secondary to psychiatric illness or malingering. It constitutes one of the differential diagnoses of fever of unknown origin (FUO). FF can be brought about by manipulation of medical findings and self-induced infection.
Factitious fever (FF) is one of the possible presentations of chronic factitious illness. Factitious fever is further categorized as one of the possible causes of fever of unknown origin (FUO). FF can be caused by a range of psychiatric and non-existing illnesses, namely Munchausen syndrome, Munchausen syndrome by proxy, malingering, and various personality disorders. The patients with FF may present with atypical symptoms of a certain disease and may appear to be genuinely ill. They may deliberately falsify their history and tamper with physical findings to achieve this. This may be done for a number of reasons, such as in order to gain attention from health professionals. Individuals with FF may also change their hospital or caregivers frequently.
Of note, FF occurs more commonly among individuals with a medical background such as medical students, nurses, pharmacists, and laboratory technicians. One proposed explanation is that it is easier for them to gain access to medical supplies, as well as to garner attention from their colleagues.
There are a number of ways in which FF can be created and these include manipulation of thermometers to show a higher reading, infecting oneself using various contaminants, and taking drugs that raise body temperature  . Self-induced infection may additionally result in recurrent episodes of skin and soft tissue infections such as cellulitis and abscesses or bacteremia that is poly-microbial. The isolated organisms could include Streptococcus viridans, Pseudomonas aeruginosa, and microbes found in fecal matter.
Other clues of FF are reported fever with no other systemic signs such as tachycardia or skin that is unusually warm to touch. FF may be a difficult diagnosis to make as FUO is in itself a challenge to clinicians . FF is, however, one of the most prominent causes of FUO .
Factitious fever should be approached with possible comorbidities and complications in mind. Possible complications of self-induced infection include bacterial endocarditis and septic pulmonary emboli. Psychiatric evaluation of the patient should also be carried out in the presence or absence of psychiatric symptoms, especially in chronic or repeated illness.
A thorough history and physical examination are instrumental in excluding possible causes of the fever  . Routine laboratory tests such as complete blood count (CBC), inflammatory markers, metabolic panel, urinalysis, and blood and urine cultures should be carried out. In addition, various imaging modalities, such as chest X-rays and ultrasound, may also be carried out at the clinician's discretion. Computed tomography (CT) and magnetic resonance imaging (MRI) scans may be incorporated as the next step in the investigation.