There are few treatments for many types of hallucinations. However, for those hallucinations caused by mental disease, a psychologist or psychiatrist should be alerted, and treatment will be based on the observations of those doctors. Antipsychotic and atypical antipsychotic medication may also be utilized to treat the illness if the symptoms are severe and cause significant distress. For other causes of hallucinations there is no factual evidence to support any one treatment is scientifically tested and proven. However, abstaining from hallucinogenic drugs, stimulant drugs, managing stress levels, living healthily, and getting plenty of sleep can help reduce the prevalence of hallucinations. In all cases of hallucinations, medical attention should be sought out and informed of one's specific symptoms.

Psychopharmacological treatments include anti-psychotic medications. Psychology research shows that first step in treatment is for the patient to realize that the voices they hear are creation of their own mind. This realization is argued to allow patients to reclaim a measure of control over their lives. Some additional psychological interventions might allow for the process of controlling these phenomena of auditory hallucinations but more research is needed.

One study from as early as 1895 reported that approximately 10% of the population experiences hallucinations. A 1996-1999 survey of over 13,000 people reported a much higher figure, with almost 39% of people reporting hallucinatory experiences, 27% of which daytime hallucinations, mostly outside the context of illness or drug use. From this survey, olfactory (smell) and gustatory (taste) hallucinations seem the most common in the general population.

To date, there is no successful method of treatment that "cures" musical hallucinations. There have been successful therapies in single cases that have ameliorated the hallucinations. Some of these successes include drugs such as neuroleptics, antidepressants, and certain anticonvulsive drugs. A musical hallucination was alleviated, for example, by antidepressant medications given to patients with depression. Sanchez reported that some authors have suggested that the use of hearing aids may improve musical hallucination symptoms. They believed that the external environment influences the auditory hallucinations, showing worsening of symptoms in quieter environments than in noisier ones. Oliver Sacks' patient, Mrs. O'C, reported being in an "ocean of sound" despite being in a quiet room due to a small thrombosis or infarction in her right temporal lobe. After treatment, Mrs. O'C was relinquished of her musical experience but said that, "I do miss the old songs. Now, with lots of them, I can't even recall them. It was like being given back a forgotten bit of my childhood again." Sacks also reported another elderly woman, Mrs. O'M, who had a mild case of deafness and reported hearing musical pieces. When she was treated with anticonvulsive medications, her musical hallucinations ceased but when asked if she missed them, she said "Not on your life."

In 73 individual cases reviewed by Evers and Ellger, 57 patients heard tunes that were familiar, while 5 heard unfamiliar tunes. These tunes ranged from religious pieces to childhood favorites, and also included popular songs from the radio. Vocal and instrumental forms of classical music were also identified in some patients. Keshavan found that the consistent feature of musical hallucinations was that it represented a personal memory trace. Memory traces refer to anything that may seem familiar to the patient, which indicated why certain childhood or familiar songs were heard.

The primary means of treating auditory hallucinations is antipsychotic medications which affect dopamine metabolism. If the primary diagnosis is a mood disorder (with psychotic features), adjunctive medications are often used (e.g., antidepressants or mood stabilizers). These medical approaches may allow the person to function normally but are not a cure as they do not eradicate the underlying thought disorder.

Given the unknown nature of MES, treatments have been largely dependent on an individual basis. Treatments can vary from being as little as self-reassurance to pharmaceutical medications.

Medications can be helpful, such as antipsychotics, benzodiazepines or antiepileptics, but there is very limited evidence for this. Some case studies have found that switching to a prednisolone steroid after a betamethasone steroid which caused MES helped alleviate hallucinations or the use of the acetylcholinesterase inhibitor, Donepezil, have also found that it successfully treated an individual's MES. However, because of the heterogeneous etiology, these methods cannot be applied as general treatment.

Other than treatment by medicinal means, individuals have also successfully alleviated musical hallucinations by cochlear implants, listening to different songs via an external source, or by attempting to block them through mental effort, depending on how severe their condition is.

The most challenging task for the examiner is to determine and obtain the correct symptoms and associate them with one of the olfactory disorders, as there are several of them and they are related to each other.

The first step the examiner usually takes is to investigate if the problem is olfactory or gustatory related. As it may be that the patient releases certain bodily odors that are causing them to have this perception.

If the examiner is able to confirm that the problem is olfactory related, the next step is to determine which olfactory disorder the patient suffers from. The following is a list of possible olfactory disorders:

- anosmia

- dysosmia

- hyperosmia

- hyposmia

- parosmia or troposmia

- phantosmia

The second step is very difficult for both the examiner and the patient as the patient has some difficulty describing their perception of the phantom odor. Furthermore, the patient is in a position of stress and anxiety thus it is crucial that the examiner be patient.

After determining the nature of the disorder, and confirming phantosmia, the examiner must then have the patient describe their perception of the phantom odor. In many cases, patients have described the odor to be that of something burning and rotten and have described it to be unpleasant and foul.

The third step for the examiner is to determine the health history of the patient to take note of head trauma, accidents, upper respiratory infections, allergic rhinitis or chronic rhinitis. Although these may be events that have resulted in the phantom odor, studies conducted by Zilstrof have found that the majority of phantosmia patients have no previous history of head trauma and upper respiratory infections.

Studies suggest that the prevalence of paraphrenia in the elderly population is around 2-4%.

Oneirophrenic patients are resistant to insulin and when injected with glucose, these patients take 30 to 50% longer to return to normal glycemia. The meaning of this finding is not known, but it has been hypothesized that it may be due to an insulin antagonist present in the blood during psychosis. However, There is currently no known treatment for oneiophrenia.

Whatever the cause, the bodily related distortions can recur several times a day and may take some time to abate. Understandably, the person can become alarmed, frightened, and panic-stricken throughout the course of the hallucinations—maybe even hurt themselves or others around them. The symptoms of the syndrome themselves are not harmful and are likely to disappear with time.

It is postulated that by the "release phenomenon" MES is caused by hypersensitivity in the auditory cortex caused by sensory deprivation, secondary to their hearing loss. This "hole" in the hearing range is "plugged" by the brain confabulating a piece of information – in this case a piece of music. A similar occurrence is seen with strokes of the visual cortex where a visual field defect occurs and the brain confabulates a piece of visual data to fill the spot. This is described by sufferers as an image in the visual field.

The hallucinations are usually not unpleasant but may cause irritation due to their persistent nature. It is common for sufferers to have a history of tinnitus.

Investigations such as magnetic resonance imaging or CT scanning and electroencephalograms (EEGs) may be worthwhile, but will rarely show any serious pathology. It is believed that because this kind of phenomenon is usually heterogenous in causation, a wide variety of factors need to be considered, which could give possible explanation for why MES is seen as under diagnosed. Some of these factors may include significant trauma to the head or any side-effects from substances such as antidepressants, marijuana, alcohol, procaine, or general anesthesia.

Psychosis is first and foremost a diagnosis of exclusion. So a new-onset episode of psychosis "cannot" be considered a symptom of a psychiatric disorder until other relevant and known causes of psychosis are properly excluded, or ruled out. Many clinicians improperly perform, or entirely miss this step, introducing avoidable diagnostic error and misdiagnosis.

An initial assessment includes a comprehensive history and physical examination by a physician, psychiatrist, psychiatric nurse practitioner or psychiatric physician assistant. Biological tests should be performed to exclude psychosis associated with or caused by substance use, medication, toxins, surgical complications, or other medical illnesses.

Delirium should be ruled out, which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness, indicating other underlying factors, including medical illnesses. Excluding medical illnesses associated with psychosis is performed by using blood tests to measure:

- Thyroid-stimulating hormone to exclude hypo- or hyperthyroidism,

- Basic electrolytes and serum calcium to rule out a metabolic disturbance,

- Full blood count including ESR to rule out a systemic infection or chronic disease, and

- Serology to exclude syphilis or HIV infection.

Other investigations include:

- EEG to exclude epilepsy, and an

- MRI or CT scan of the head to exclude brain lesions.

Because psychosis may be precipitated or exacerbated by common classes of medications, medication-induced psychosis should be ruled out, particularly for first-episode psychosis. Both substance- and medication-induced psychosis can be excluded to a high level of certainty, using a

- Urinalysis and a

- Full serum toxicology screening.

Because some dietary supplements may also induce psychosis or mania, but cannot be ruled out with laboratory tests, a psychotic individual's family, partner, or friends should be asked whether the patient is currently taking any dietary supplements.

Common mistakes made when diagnosing people who are psychotic include:

- Not properly excluding delirium,

- Not appreciating medical abnormalities (e.g., vital signs),

- Not obtaining a medical history and family history,

- Indiscriminate screening without an organizing framework,

- Missing a toxic psychosis by not screening for substances "and" medications

- Not asking family or others about dietary supplements,

- Premature diagnostic closure, and

- Not revisiting or questioning the initial diagnostic impression of primary psychiatric disorder.

Only after relevant and known causes of psychosis are excluded, a mental health clinician may make a psychiatric differential diagnosis using a person's family history, incorporating information from the person with psychosis, and information from family, friends, or significant others.

Types of psychosis in psychiatric disorders may be established by formal rating scales. The Brief Psychiatric Rating Scale (BPRS) assesses the level of 18 symptom constructs of psychosis such as hostility, suspicion, hallucination, and grandiosity. It is based on the clinician's interview with the patient and observations of the patient's behavior over the previous 2–3 days. The patient's family can also answer questions on the behavior report. During the initial assessment and the follow-up, both positive and negative symptoms of psychosis can be assessed using the 30 item Positive and Negative Symptom Scale (PANSS).

While paraphrenia can occur in both men and women, it is more common in women, even after the difference has been adjusted for life expectancies. The ratio of women with paraphrenia to men with paraphrenia is anywhere from 3:1 to 45:2

Research needs to be performed on the efficacy of the various pharmaceuticals for treating illusory palinopsia. It is unclear if the symptoms' natural history and treatment are influenced by the cause. It is also not clear if there is treatment efficacy overlap for illusory palinopsia and the other co-existing diffuse persistent illusory phenomenon such as visual snow, oscillopsia, dysmetropsia, and halos.

Future advancements in fMRI could potentially further our understanding of hallucinatory palinopsia and visual memory. Increased accuracy in fMRI might also allow for the observation of subtle metabolic or perfusional changes in illusory palinopsia, without the use of ionizing radiation present in CT scans and radioactive isotopes. Studying the psychophysics of light and motion perception could advance our understanding of illusory palinopsia, and vice versa. For example, incorporating patients with visual trailing into motion perception studies could advance our understanding of the mechanisms of visual stability and motion suppression during eye movements (e.g. saccadic suppression).

Treatment of any kind of complex visual hallucination requires an understanding of the different pathologies in order to correctly diagnose and treat. If a person is taking a pro-hallucinogenic medication, the first step is to stop taking it. Sometimes improvement will occur spontaneously and pharmacotherapy is not necessary. While there is not a lot of evidence of effective pharmacological treatment, antipsychotics and anticonvulsants have been used in some cases to control hallucinations. Since peduncular hallucinosis occurs due to an excess of serotonin, modern antipsychotics are used to block both dopamine and serotonin receptors, preventing the overstimulation of the lateral geniculate nucleus. The drug generically called carbamazepine increases GABA, which prevents the LGN from firing, thereby increasing the inhibition of the LGN. Regular antipsychotics as well as antidepressants can also be helpful in reducing or eliminating peduncular hallucinosis.

More invasive treatments include corrective surgery such as cataract surgery, laser photocoagulation of the retina, and use of optical correcting devices. Tumor removal can also help to relieve compression in the brain, which can decrease or eliminate peduncular hallucinosis. Some hallucinations may be due to underlying cardiovascular disease, so in these cases the appropriate treatment includes control of hypertension and diabetes. As described, the type of treatment varies widely depending on the causation behind the complex visual hallucinations.

Research efforts are focusing on prevention in identifying early signs from relatives with associated disorders similar with schizophrenia and those with prenatal and birth complications. Prevention has been an ongoing challenge because early signs of the disorder are similar to those of other disorders. Also, some of the schizophrenic related symptoms are often found in children without schizophrenia or any other diagnosable disorder.

Tactile hallucination is the false perception of tactile sensory input that creates a hallucinatory sensation of physical contact with an imaginary object. It is caused by the faulty integration of the tactile sensory neural signals generated in the spinal cord and the thalamus and sent to the primary somatosensory cortex (SI) and secondary somatosensory cortex (SII). Tactile hallucinations are recurrent symptoms of neurological diseases such as schizophrenia, Parkinson's disease, Ekbom's syndrome and delerium tremens. Patients who experience phantom limb pains also experience a type of tactile hallucination. Tactile hallucinations are also caused by drugs such as cocaine and alcohol.

Differential diagnosis includes ruling out other causes such as drug-induced conditions, dementia, infections, metabolic disorders, and endocrine disorders. Other psychiatric disorders must then be ruled out. In delusional disorder, mood symptoms tend to be brief or absent, and unlike schizophrenia, delusions are non-bizarre and hallucinations are minimal or absent.

Interviews are important tools to obtain information about the patient's life situation and past history to help make a diagnosis. Clinicians generally review earlier medical records to gather a full history. Clinicians also try to interview the patient's immediate family, as this can be helpful in determining the presence of delusions. The mental status examination is used to assess the patient's current mental condition.

A psychological questionnaire used in the diagnosis of the delusional disorder is the Peters Delusion Inventory (PDI) which focuses on identifying and understanding delusional thinking. However, this questionnaire is more likely used in research than in clinical practice.

In terms of diagnosing a non-bizarre delusion as a delusion, ample support should be provided through fact checking. In case of non-bizarre delusions, Psych Central notes, "All of these situations could be true or possible, but the person suffering from this disorder knows them not to be (e.g., through fact-checking, third-person confirmation, etc.)."

A longitudinal study on pregnant females found that 76% of pregnant females experienced significant changes in gustation and olfaction perception. This was found to be caused and linked to their pregnancy. The study concluded that 67% of the pregnant females had reported a higher level of sensitivity to smell, 17% suffered from an olfactory distortion and 14% suffered from phantosmia; these distortions were very minimal towards the last stages of pregnancy and in the majority were not present post partum. Furthermore, 26% of these participants also claimed that they also experienced an increased sensitivity to foods that were bitter and a decreased sensitivity to salt. These findings suggest that pregnant females experience distorted smell and taste perception during pregnancy. It has also been found that 75% of women alter their diets during pregnancy. Further research is being conducted to determine the mechanism behind food cravings during pregnancy.

Alice in Wonderland syndrome is a disturbance of perception rather than a specific physiological change to the body's systems. The diagnosis can be presumed when other causes have been ruled out and if the patient presents symptoms along with migraines and complains of onset during the day (although it can also occur at night).

Another symptom of Alice in Wonderland syndrome is sound distortion, such as every little movement making a clattering sound.

Peduncular hallucinosis (PH), or Lhermitte's peduncular hallucinosis, is a rare neurological disorder that causes vivid visual hallucinations that typically occur in dark environments, and last for several minutes. Unlike some other kinds of hallucinations, the hallucinations that patients with PH experience are very realistic, and often involve people and environments that are familiar to the affected individuals. Because the content of the hallucinations is never exceptionally bizarre, patients can rarely distinguish between the hallucinations and reality.

In 1922, the French neurologist Jean Lhermitte documented the case of a patient who was experiencing visual hallucinations that were suggestive of localized damage to the midbrain and pons. After other similar case studies were published, this syndrome was labeled "peduncular hallucinosis."

The accumulation of additional cases by Lhermitte and by others influenced academic medical debate about hallucinations and about behavioral neurology.

Lhermitte provided a full account of his work in this area in his book "Les hallucinations: clinique et physiopathologie," which was published in Paris in 1951 by Doin publishing.

Contemporary researchers, with access to new technologies in medical brain imaging, have confirmed the brain localization of these unusual hallucinations.

A pseudohallucination is an involuntary sensory experience vivid enough to be regarded as a hallucination, but recognised by the patient not to be the result of external stimuli. Unlike normal hallucinations, which occurs when one sees, hears, smells, tastes or feels something that is not there, with a compelling feeling or thought that it is real, pseudohallucinations are recognised by the person as unreal.

In other words, it is a hallucination that is recognized as a hallucination, as opposed to a "normal" hallucination which would be perceived as real. An example used in psychiatry is the hearing of voices which are "inside the head" according to the patient; in contrast, a hallucination would be indistinguishable to the patient from a real external stimulus, e.g. "people were talking about me".

The term is not widely used in the psychiatric and medical fields, as it is considered ambiguous; the term "nonpsychotic hallucination" is preferred. Pseudohallucinations, then, are more likely to happen with a hallucinogenic drug. But "the current understanding of pseudohallucinations is mostly based on the work of Karl Jaspers".

A further distinction is sometimes made between pseudohallucinations and "parahallucinations", the latter being a result of damage to the peripheral nervous system.

They are considered a feature of conversion disorder, somatization disorder, and dissociative disorders. Also, pseudohallucinations can occur in people with visual/hearing loss, with the typical such type being Charles Bonnet syndrome.

Because there is no prescribed treatment, the first starting place is to reassure the CBS sufferer of their sanity, and some charities provide specialist hallucination counselling "buddies" (people who have had CBS, or have CBS and are no longer fazed by it) to talk to on the telephone. Sometimes it is carers and/or physicians that need advice and guidance.

The physician will consider on a case-by-case basis whether to treat any depression or other problems that may be related to CBS. A recent case report suggests selective serotonin reuptake inhibitors may be helpful.

There is no treatment of proven effectiveness for CBS. Some people experience CBS for anywhere from a few days up to many years, and these hallucinations can last only a few seconds or continue for most of the day. For those experiencing CBS, knowing that they are suffering from this syndrome and not a mental illness seems to be the best treatment so far, as it improves their ability to cope with the hallucinations. Most people with CBS meet their hallucinations with indifference, but they can still be disturbing because they may interfere with daily life. Interrupting vision for a short time by closing the eyes or blinking is sometimes helpful.