This is described as a rare form of severe mental illness, with the following characteristics:

- Sudden onset in a previously asymptomatic person.

- Brief duration, with full recovery.

- Psychotic symptoms that can include confusion or hallucinations, mutism and stupor, delusions, or manic state. These are distinct from premenstrual tension, premenstrual syndrome, premenstrual (late luteal phase) depression or dysphoric disorder or menstrual mood disorder.

- Occurrence in rhythm with the menstrual cycle.

It shares clinical features with, and presents similarly to, postpartum psychosis. Researchers Deuchar and Brockington proposed that a sudden drop in levels of estrogen in the brain could be the trigger for both conditions.

Symptoms usually begin suddenly in the first two weeks after delivery, sometimes in the first two to three days after giving birth. Symptoms vary and can change quickly, and can include high mood and racing thoughts (mania), depression, severe confusion, losing inhibitions, paranoia, hallucinations and delusions.

In contrast, about half of women have the maternity blues after birth, which is characterized by symptoms of mild mood swings, anxiety, and irritability that start about 3 to 4 days after delivery and last about a week; postpartum depression is also different — it is experienced by 10 to 15% of women after birth and is similar to major depressive disorder.

Postpartum psychosis is a psychiatric emergency related to care of women after they give birth. It is different from postpartum depression and from maternity blues.

The condition is not recognized in the DSM-5 nor in the ICD-10 but it is widely used clinically.

It may be a form of bipolar disorder.

Menstrual psychosis is a debated form of psychosis with a brief, sudden onset related to the menstrual cycle. The symptoms associated to it are dramatic and include delirium, mania or mutism. Most psychiatrists do not recognise the condition. Only 80 established cases are reported in medical literature and most of them were described by 19th Century physicians. It is thought to be linked with postpartum psychosis. This journal has been published looking at the 'evidence' for menstrual psychosis'.

Symptoms of psychotic breaks vary greatly, usually depending on the circumstances of diagnosis or any contributary substance ingested. Symptoms can range from harmless, sometimes unnoticed delusions, to violent outbursts and major depression. The sufferer may also be unable to distinguish reality from fantasy (for example, believing that a dream really happened or experiencing hallucinations that appear to be real). When a bipolar disorder is involved: crying, grandiosity, insomnia, irritability, and persecutory delusions may all or severally manifest themselves as symptoms.

The disorder is characterized by a sudden onset of psychotic symptoms, which may include delusions, hallucinations, disorganized speech or behavior, or catatonic behavior. The symptoms must not be caused by schizophrenia, schizoaffective disorder, delusional disorder or mania in bipolar disorder. They must also not be caused by a drug (such as amphetamines) or medical condition (such as a brain tumor). The term bouffée délirante describes an acute nonaffective and nonschizophrenic psychotic disorder, which is largely similar to DSM-III-R and DSM-IV brief psychotic and schizophreniform disorders.

Symptoms generally last at least a day, but not more than a month, and there is an eventual return to full baseline functioning. It may occur in response to a significant stressor in one's life, or in other situations where a stressor is not apparent, including in the weeks following birth. In diagnosis, a careful distinction is considered for culturally appropriate behaviors, such as religious beliefs and activities. It is believed to be connected to or synonymous with a variety of culture-specific phenomena such as latah, koro, and amok.

There are three forms of brief psychotic disorder:

1. Brief psychotic disorder with a stressor, such as a trauma or death in the family.

2. Brief psychotic disorder without a stressor, there is no obvious stressor.

3. Brief psychotic disorder with postpartum onset. Usually occurs about four weeks after giving birth.

People with psychosis normally have one or more of the following:

- hallucinations

- delusions

- catatonia

- thought disorder.

Impairments in social cognition also occur.

Many things can cause temporary psychosis. Environmental triggers, such as losing a loved one, are known to contribute, as may excessive stress, or the interaction of strong social demands with a pre-existing vulnerability of self.

Other causes that have been identified include lack of sleep, fever, brain damage, and even hypnosis. War/battlefield experience may also trigger a psychotic break: when reality becomes unbearable, the mind temporarily breaks with it. Parenthood may occasionally set off a psychotic break in men, as may giving birth in women who have previously denied their pregnancy.

Several types of psychoactive drugs have been shown to correlate with psychotic breaks. The compulsive drug user may find their ego dissociating in a psychotic break if habituation means the drug can no longer fulfill its defensive function.

Though less common than stimulant psychosis, stimulants such as cocaine and amphetamines as well as the dissociative drug phencyclidine (PCP, angel dust) may also cause a theorized severe and life-threatening condition known as excited delirium. This condition manifests as a combination of delirium, psychomotor agitation, anxiety, delusions, hallucinations, speech disturbances, disorientation, violent and bizarre behavior, insensitivity to pain, elevated body temperature, and superhuman strength. Despite some superficial similarities in presentation excited delirium is a distinct (and more serious) condition than stimulant psychosis. The existence of excited delirium is currently debated.

A hallucination is defined as sensory perception in the absence of external stimuli. Hallucinations are different from illusions, or perceptual distortions, which are the misperception of external stimuli. Hallucinations may occur in any of the senses and take on almost any form, which may include simple sensations (such as lights, colors, tastes, and smells) to experiences such as seeing and interacting with fully formed animals and people, hearing voices, and having complex tactile sensations.

Auditory hallucinations, particularly experiences of hearing voices, are the most common and often prominent feature of psychosis. Hallucinated voices may talk about, or to, the person, and may involve several speakers with distinct personalities. Auditory hallucinations tend to be particularly distressing when they are derogatory, commanding or preoccupying. However, the experience of hearing voices need not always be a negative one. One research study has shown that the majority of people who hear voices are not in need of psychiatric help. The Hearing Voices Movement has subsequently been created to support voice hearers, regardless of whether they are considered to have a mental disorder or not.

Postpartum depression onset usually begins between two weeks to a month after delivery. Recent studies have shown that 50% of postpartum depressive episodes begin prior to delivery. Therefore, in the DSM-5 postpartum depression is diagnosed under "depressive disorder with peripartum onset", in which "peripartum onset" is defined as anytime either during pregnancy or within the four weeks following delivery. PPD may last several months or even a year. Postpartum depression can also occur in women who have suffered a miscarriage.

Symptoms of PPD can occur any time in the first year postpartum. Typically, a diagnosis of postpartum depression is considered after signs and symptoms persist for at least two weeks. These symptoms include, but are not limited to:

The symptoms of stimulant psychosis vary depending on the drug ingested, but generally involve the symptoms of organic psychosis such as hallucinations, delusions, paranoia, and thought disorder.

Individuals with schizophrenia may experience hallucinations (most reported are hearing voices), delusions (often bizarre or persecutory in nature), and disorganized thinking and speech. The last may range from loss of train of thought, to sentences only loosely connected in meaning, to speech that is not understandable known as word salad. Social withdrawal, sloppiness of dress and hygiene, and loss of motivation and judgment are all common in schizophrenia.

Distortions of self-experience such as feeling as if one's thoughts or feelings are not really one's own to believing thoughts are being inserted into one's mind, sometimes termed passivity phenomena, are also common. There is often an observable pattern of emotional difficulty, for example lack of responsiveness. Impairment in social cognition is associated with schizophrenia, as are symptoms of paranoia. Social isolation commonly occurs. Difficulties in working and long-term memory, attention, executive functioning, and speed of processing also commonly occur. In one uncommon subtype, the person may be largely mute, remain motionless in bizarre postures, or exhibit purposeless agitation, all signs of catatonia. People with schizophrenia often find facial emotion perception to be difficult. It is unclear if the phenomenon called "thought blocking", where a talking person suddenly becomes silent for a few seconds to minutes, occurs in schizophrenia.

About 30 to 50 percent of people with schizophrenia fail to accept that they have an illness or comply with their recommended treatment. Treatment may have some effect on insight.

People with schizophrenia may have a high rate of irritable bowel syndrome but they often do not mention it unless specifically asked. Psychogenic polydipsia, or excessive fluid intake in the absence of physiological reasons to drink, is relatively common in people with schizophrenia.

Schizophrenia is often described in terms of positive and negative (or deficit) symptoms. "Positive symptoms" are those that most individuals do not normally experience, but are present in people with schizophrenia. They can include delusions, disordered thoughts and speech, and tactile, auditory, visual, olfactory and gustatory hallucinations, typically regarded as manifestations of psychosis. Hallucinations are also typically related to the content of the delusional theme. Positive symptoms generally respond well to medication.

"Negative symptoms" are deficits of normal emotional responses or of other thought processes, and are less responsive to medication. They commonly include flat expressions or little emotion, poverty of speech, inability to experience pleasure, lack of desire to form relationships, and lack of motivation. Negative symptoms appear to contribute more to poor quality of life, functional ability, and the burden on others than positive symptoms do. People with greater negative symptoms often have a history of poor adjustment before the onset of illness, and response to medication is often limited.

The validity of the positive and negative construct has been challenged by factor analysis studies observing a three dimension grouping of symptoms. While different terminology is used, a dimension for hallucinations, a dimension for disorganization, and a dimension for negative symptoms are usually described.

Brief psychotic disorder is a period of psychosis whose duration is generally shorter, is not always non-recurring, but can be, and is not caused by another condition.

Schizoaffective disorder is defined by "mood disorder-free psychosis" in the context of a long-term psychotic and mood disorder. Psychosis must meet criterion A for schizophrenia which may include delusions, hallucinations, disorganized speech, thinking or behavior and negative symptoms. Both delusions and hallucinations are classic symptoms of psychosis. Delusions are false beliefs which are strongly held despite evidence to the contrary. Beliefs should not be considered delusional if they are in keeping with cultural beliefs. Delusional beliefs may or may not reflect mood symptoms (for example, someone experiencing depression may or may not experience delusions of guilt). Hallucinations are disturbances in perception involving any of the five senses, although auditory hallucinations (or "hearing voices") are the most common. A lack of responsiveness or negative symptoms include alogia (lack of spontaneous speech), blunted affect (reduced intensity of outward emotional expression), avolition (loss of motivation), and anhedonia (inability to experience pleasure). Negative symptoms can be more lasting and more debilitating than positive symptoms of psychosis.

Mood symptoms are of mania, hypomania, mixed episode, or depression, and tend to be episodic rather than continuous. A mixed episode represents a combination of symptoms of mania and depression at the same time. Symptoms of mania include elevated or irritable mood, grandiosity (inflated self-esteem), agitation, risk-taking behavior, decreased need for sleep, poor concentration, rapid speech, and racing thoughts. Symptoms of depression include low mood, apathy, changes in appetite or weight, disturbances in sleep, changes in motor activity, fatigue, guilt or feelings of worthlessness, and suicidal thinking.

Brief reactive psychosis generally follows a recognisably traumatic life event like divorce or homelessness, but may be triggered by any subjective experience which appears catastrophic to the person affected.

Among such stressors are the death of a loved one, professional loss such as unexpectedly losing one's job or otherwise becoming unemployed, or serious adverse changes in the patient's personal life, such as the breakdown of their family through divorce, etc.

It must be emphasised that this is by no means an exhaustive list of stressful life events, because the events which trigger brief reactive psychosis tend, due to the individualistic nature of human psychology, to be extremely personalized. BRP may be the first breakdown for someone with a chronic psychiatric disorder but only time will tell whether the disorder will be brief or lifelong, whether BRP or a chronic condition that is controlled well enough by medication that symptoms do not return.

Tardive psychosis is a term for a hypothetical form of psychosis, proposed in 1978. It was defined as a condition caused by long term use of neuroleptics, noticeable when the medication had become decreasingly effective, requiring higher doses, or when not responding to higher doses.

Evaluation suggests that tardive psychosis as a whole is a combination of "several different and not necessarily correlated phenomena related to neuroleptic treatment of schizophrenia."

Some articles equate tardive psychosis to supersensitivity psychosis. However, descriptions of symptoms of the latter do not match the former. Specific supersensitivity psychosis articles only address psychotic episodes in the wake of psychotic medication withdrawal associated with Clozapine. They do not mention medication resistance, which is the cornerstone of tardive psychosis theory.

A hypothetical condition related to tardive psychosis, tardive dysmentia, has also been questioned.

Supersensitivity psychosis is used to discuss the spontaneous occurrence of psychotic episodes and/or the appearance of tardive dykinesia in the wake of anti-psychotic medication withdrawal.

Such spontaneous episodes have occurred even in patients who never had psychotic episodes before beginning the medication. Studies using Clozapine have found significant evidence.

Larger discussions of withdrawal from other antipsychotics usually focus on tardive dyskinesia, a far more significant and long-lasting side effect of antipsychotic treatment.

When supersensitivity psychosis was explored in 1978, a featured concern was increasing resistance to medication, requiring higher doses or not responding to higher doses. Some articles use the term tardive psychosis to reference to this specific concept. However, articles have disputed its' validity. The condition has been discovered in very few people. Palmstierna asserts that tardive psychosis is a combination of "several different and not necessarily correlated phenomena related to neuroleptic treatment of schizophrenia."

However, some articles use the term tardive psychosis as equivalent to supersensitivity psychosis.

Alcohol withdrawal states (delirium tremens) are recognized in addicts whose intake has been interrupted by trauma or surgery. This can occur after childbirth.

Oneirophenia and schizophrenia are often confused although there are distinct differences between the conditions. Oneirophrenia has some of the characteristics of simple schizophrenia, such as a confusional state and clouding of consciousness, but without presenting the dissociative symptoms which are typical of that disorder. Oneiophrenia often begins with the inability to focus on things while schizophrenia frequently starts with a traumatic event. Persons affected by oneirophrenia have a feeling of dream-like derealization which, in its extreme form, may progress to delusions and hallucinations. Therefore, it is considered a schizophrenia-like acute form of psychosis which remits in about 60% of cases within a period of two years. It is estimated that 50% or more of schizophrenic patients present oneirophrenia at least once.

Psychosis manifests as disorientation, visual hallucinations and/or haptic hallucinations. It is a state in which a person's mental capacity to recognize reality, communicate, and relate to others is impaired, thus interfering with the capacity to deal with life demands. While there are many types of psychosis, substance-induced psychosis can be pinpointed to specific chemicals.

In medicine, a prodrome is an early sign or symptom (or set of signs and symptoms), which often indicate the onset of a disease before more diagnostically specific signs and symptoms develop. It is derived from the Greek word "prodromos", meaning "running before". Prodromes may be non-specific symptoms or, in a few instances, may clearly indicate a particular disease, such as the prodromal migraine aura.

For example, fever, malaise, headache and lack of appetite frequently occur in the prodrome of many infective disorders. A prodrome can be the early precursor to an episode of a chronic neurological disorder such as a migraine headache or an epileptic seizure, where prodrome symptoms may include euphoria or other changes in mood, insomnia, abdominal sensations, disorientation, aphasia, or photosensitivity. Such a prodrome occurs on a scale of days to an hour before the episode, where an aura occurs more immediate to it.

Prodromal labour, mistakenly called "false labour," refers to the early signs before labour starts.

At risk mental state is the clinical presentation of those considered at risk of developing psychosis or schizophrenia. Such states were formerly considered treated as prodromes, emerging symptoms of psychosis, but this view is no longer prevalent as a prodromal period can not be confirmed unless the emergence of the condition has occurred.

The original specialist service for those with subclinical symptoms of psychosis was "The Pace Clinic" in Melbourne, Australia. Other clinics have since developed around the world.

There has been some considerable development of how the concept can be applied clinically.

Assessed during the structured interview developed by PACE.