The symptoms of Brief Psychotic Disorder come on suddenly. As the name suggests however it is very brief, the episode normally lasts for less than four weeks.

The symptoms from the onset include hallucinations. This can be either be visual hallucinations (seeing things that are not there) or audio hallucinations in which the sufferer hears voices in their head. They may suffer from delusions, false beliefs that they hold despite the evidence to the contrary. Other symptoms can include disorientation, the use of peculiar speech (putting words together in a completely incoherent order) and eccentric very bizarre behaviour. Catatonic behaviour is also a common symptom. This can be at both ends of the scale, either remaining fixed and motionless for hours or repeated rapid movements along with strange facial expressions. To the onlooker this can be very unsettling and frightening.

This short term disorder has no real known cause, but it is thought that severe stress, hormonal changes after childbirth, or a traumatic event can trigger the condition. Some think Brief Psychotic Disorder can be the first sign that the individual will go onto develop a more serious mental health disorder like schizophrenia.