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Psychosis can be a frightening word that many people simply don’t understand. But what does it really mean? In Parkinson’s disease (PD), what your doctor calls psychosis usually starts with mild symptoms, but these can have a big impact on quality of life. Psychosis can vary from severe confusion (disordered thinking) to seeing things that aren’t there (hallucinations) to believing things that are not true (delusions).

It is important to report any hallucinations or delusions to your medical team, even if they are not bothersome. Mental health professionals can help.

What are hallucinations?

Hallucinations are when someone sees, hears or feels something that is not actually there. Hallucinations are not dreams or nightmares. They happen when the person is awake and can occur at any time of day or night.

  • Hallucinations are best described as deceptions or tricks played by the brain that involve the body’s senses. 
  • Can be seen (visual), heard (auditory), felt (tactile), smelled (olfactory) or even tasted (gustatory).
  • May appear real.
  • About 20 to 30 percent of people with PD who take medications to improve mobility experience visual hallucinations.

Types of hallucinations include:

  • Visual: Seeing a furry creature run by or seeing a deceased love one sitting in the room. These are the most common in PD.
  • Auditory: Perceiving voices or sounds that are not real. These are uncommon, but reported by a small percentage of people with PD.
  • Olfatory: Smelling an unpleasant odor that is not related to another source. This is rare in PD.
  • Tactile: Feeling imaginary bugs crawling on your skin. This is rare in PD.
  • Gustatory: Tasting a bitter or abnormal taste in your mouth that is not related to another source. This is rare in PD.

Hallucinations are most often a side effect of medication and are not necessarily a sign of a decline in cognitive abilities. Hallucinations most often experienced by people with PD are fleeting and non-threatening. However, in some cases hallucinations may become threatening or bothersome.


  • Visual hallucinations are the most common type experienced by people with PD and tend to appear in the evening or at night. They are often an illusion or misperception. For example, the clothes in the closet may look like a group of people.
  • Although hallucinations can affect anyone taking medication to manage PD symptoms, they are more common in people who have problems in thinking or memory, or when under a medical stress.
  • Hallucinations may occur in the peripheral vision (out of the corner of the eye), in the form of a flash of light, people or small animals such as cats or dogs. Images often disappears when the person looks more closely.
  • Sometimes people with PD have presence hallucinations — the feeling that someone is in the room with them or standing behind them. 
  • Usually illusions and hallucinations are not frightening and the person is aware they are occurring. However, some people find them incredibly real.

Discuss all possible symptoms with your doctor, no matter how minor, rare or bizarre.

Tips for Living with Hallucinations

It is important people with PD talk about hallucinations with their family and care team because they are manageable and can be troublesome if not treated.

  • Good lighting and stimulating activities in the evening can help keep hallucinations at bay.
  • While a hallucination is occurring, caregivers can reassure their loved one by validating their partner’s experience and reassuring that they will be safe from frightening ones.

What Are Delusions?

Delusions are illogical, irrational, dysfunctional views or persistent thoughts that are not based in reality. They are not deliberate and can be real to the person with PD. Common types of delusions include paranoia or accusations of marital infidelity. People with delusions who feel threatened may become argumentative, aggressive, agitated or unsafe.

  • Less common in PD than visual hallucinations, affecting approximately eight percent of people with PD. Delusions tend to be more complicated, present a greater risk for behavioral disturbances and safety concerns and are typically more difficult to treat than hallucinations.
  • Represent a more obvious deterioration or decline in one’s condition. 
  • Delusions can begin as generalized confusion at night. Over time, confusion can develop into clear delusions and behavioral disturbances during the day.
  • All forms of delusions can be seen with PD, although delusions of jealousy and persecution (like paranoia) are most widely reported and represent a greater challenge for treatment. This type can lead to aggression, which can pose a serious safety risk to the person with PD, family members and caregivers.
  • Paranoia can lead to medication noncompliance — a person can refuse to take medications, believing they are poisonous or deadly.
  • Can also be associated with dementia. As a result, people with delusions are often confused and extremely difficult to manage. In these cases, many caregivers require outside assistance.

Some examples of delusions in PD include:

  • Jealousy
  • Belief: Your partner is being unfaithful.
  • Behavior: Paranoia, agitation, suspiciousness, aggression.
  • Persecutory
  • Belief: You are being attacked, harassed, cheated or conspired against.
  • Behavior: Paranoia, suspiciousness, agitation, aggression, defiance, social withdrawal.
  • Somatic
  • Belief: Your body functions in an abnormal manner. You develop an unusual obsession with your body or health.
  • Behavior: Anxiety, agitation, reports of abnormal or unusual symptoms, extreme concern regarding symptoms, frequent visits with the clinician.

Treating Hallucinations and Delusions

It is important to tell your family and doctor if you are experiencing hallucinations or any related symptoms. The doctor will review your health status and medications and come up with a treatment plan if needed.

Since it is common for certain infections to exacerbate symptoms of hallucinations or delusions, your doctor may look for signs of infection. One of the most likely causes is a urinary tract infection, so a urine test may be performed.

Keep in mind that:

  • Treatment for hallucinations depends on how much they bother a person or interfere with life.
  • To ensure proper treatment, the underlying cause must first be identified.
  • Blood work and other testing may be necessary. Once a probable cause is determined, treatment can begin.

Treating Hallucinations and Delusions Caused by Parkinson’s Medications

Your doctor can determine if your Parkinson’s treatments are the cause and if medication adjustments can help. PD medications relieve motor symptoms by increasing dopamine in the brain. Work with your health care team to balance medications, which can sometimes elevate dopamine levels triggering hallucinations and delusions.

In many cases, hallucinations and delusions occur as a side effect of drug therapy. Many PD medications can potentially cause these symptoms:

  • Classic PD medications like carbidopa-levodopa (Sinemet) and dopamine agonists are designed to increase dopamine levels, improving motor symptoms; however, by boosting the dopamine supply, these medications can inadvertently cause serious emotional and behavioral changes.
  • Other medications used to treat PD can also cause these symptoms a little bit more often by lowering levels of acetylcholine and shifting its balance with dopamine. These medications include anticholinergics (Artane and Cogentin) and amantadine.

Keep in mind that:

  • Hallucinations do not necessarily indicate that PD medications need to be changed.
  • A clinician must first determine if hallucinations or delusions are related to medication side effects, dementia or delirium. This can be difficult because these conditions can overlap and produce similar symptoms.
  • If a change in medication is in order, the first step usually is to eliminate medications that are no longer needed, followed by reducing medications taken for PD movement symptoms.

Making changes in Parkinson’s medications can be a complicated process. On one side of the scale, high dopamine levels are needed for adequate control of PD motor symptoms. On the other, dopamine levels need to be reduced to alleviate hallucinations and delusions. To determine the change in medication, many doctors will use a three-step approach:

STEP 1: Assessment and Plan

  • Assess the problem.
  • Determine if hallucinations and delusions are benign or problematic. Some clinicians will postpone treatment if symptoms are infrequent, non-threatening and if the person with PD retains insight. Other clinicians will start treatment based on the theory that hallucinations and delusions worsen over time.
  • Ensure there is no provoking factor, such as a urinary tract infection.

STEP 2: Adjust or Reduce Parkinson’s Medications

  • Your provider may adjust your PD medications. The goal is to reduce hallucinations and delusions without worsening PD motor symptoms. The clinician may decide to skip this step and proceed to Step 3 if the person with PD is unable to tolerate potential worsening of PD symptoms.
  • The following recommendations have been made for reducing or discontinuing PD medications for the management of hallucinations and delusions. Your doctor will decide to reduce or discontinue medications in the following order until hallucinations or delusions improve:
    • Anticholinergic medications [trihexyphenidyl (artane)]
    • Amantadine
    • Dopamine agonists [Pramipexole (Mirapex ®), Ropinerole (Requip), Rotigotine (Neupro)]
    • COMT inhibitors [Entacapone (Comtan ®)]
    • MAOB inhibitors [Rasagiline (Azilect), Selegiline (Eldepryl)]
    • Carbidopa-Levodopa (Sinemet IR, Sinemet CR, Rytary)

This approach generally improves psychotic symptoms, however, if motor symptoms become worse, PD medications may need to be restarted or increased, with Carbidopa-Levodopa (Sinemet) being the core of therapy and Step 3 started.

If it is not possible to take a lower dose of PD medications, your doctor may prescribe a low dose of a cholinesterase inhibitor like donepezil (Aricept®) or rivastigmine (Exelon®) or a low dose of an antipsychotic drug like quetiapine (Seroquel®) or clozapine (Clozaril®). Due to a condition affecting the blood cells, those taking clozapine (Clozaril®) may need monitoring with frequent lab tests.

STEP 3: Initiating Antipsychotic Therapy

Antipsychotic agents are designed to balance abnormal chemical levels in the brain. They work by reducing excess dopamine, thereby alleviating psychosis. Up until the 1990s, the use of antipsychotics in PD had been controversial. This was because older (also known as typical) antipsychotic medications were found to cause dramatic worsening of PD motor symptoms.

Fortunately, medications that are better tolerated by people with PD are now available. This newer class of medications is referred to as atypical antipsychotics. Today, there are three antipsychotic medications considered relatively safe for people with PD: quetiapine (Seroquel®), clozapine (Clozaril®) and the newest agent pimavanserin (Nuplazid®). They cause limited worsening of PD while treating hallucinations and delusions.

How to Talk to Someone with Hallucinations or Delusions

It is usually not helpful to argue with someone who is experiencing a hallucination or delusion. Avoid trying to reason. Keep calm and be reassuring.

You can say you do not see what your loved one is seeing, but some people find it more calming to acknowledge what the person is seeing to reduce stress. For example, if the person sees a cat in the room, it may be best to say, "I will take the cat out" rather than argue that there is no cat. Some people call this therapeutic fibbing.


Dementia is a term used the describe a group of symptoms associated with a decline in memory and thinking. It is commonly associated with conditions, such as Alzheimer’s disease, but people with PD can also develop it.

  • Hallucinations and delusions can result from the basic chemical and physical changes that occur in the brain, regardless of other factors such as PD medications. This is most commonly seen in cases of PD with dementia.
  • If psychosis and dementia occur early in the disease process doctors may consider a diagnosis of dementia with Lewy bodies.


Delirium is a reversible change in a person's level of attention and concentration.

  • Usually develops over a short period of time (hours to days) and resolves following treatment of the underlying condition.
  • Signs of delirium include: altered consciousness or awareness, disorganized thinking, unusual behavior and hallucinations.
  • Because there are so many symptoms, delirium can be confused with other conditions, such as dementia or drug-induced psychosis.
  • To diagnose delirium, a person’s level of concentration or attention must go through a change.
  • People with Parkinson's have a higher risk of delirium when admitted to the hospital, due to the new settings for the procedure or surgery, which may be unrelated to their PD.

Common causes of delirium include:

  • Infection, such as urinary tract infection or pneumonia
  • Imbalance of sodium, potassium, calcium or other electrolytes
  • Stroke
  • Heart disease
  • Liver disease
  • Fever
  • Vitamin B12 deficiency
  • Head injury
  • Sensory changes, such as hearing loss and vision changes

In addition to medical conditions and changes, many commonly used drugs and chemicals can also cause delirium:

  • Anticholinergic medications: diphenhydramine hydrochloride (Benadryl®), trihexyphenidyl (Artane®), Benztropine (Cogentin®), ranitidine (Zantac®) and oxybutynin (Ditropan®)
  • Narcotics containing codeine or morphine
  • Antibiotics
  • Nonsterodial anti-inflammatory drugs (NSAIDS) including Aleve®, Motrin® and Advil ®
  • Insulin
  • Sedatives
  • Steroids
  • Anti-seizure medications
  • Alcohol
  • Recreational drugs

What are risk factors for psychosis?

Several factors can increase the risk of developing psychosis:

  • Dementia or impaired memory
  • Depression: Individuals suffering from depression and PD are at a greater risk. In addition, severe depression alone can cause psychosis.
  • Sleep disorders, such as vivid dreaming. Individuals commonly report vivid dreaming prior to the onset of psychosis. Other associated sleep disturbances include REM sleep disorder and general insomnia.
  • Impaired vision
  • Older age
  • Advanced or late-stage PD
  • Use of PD medications

Medications Used for Treating Psychosis


  • Most often prescribed to be taken just before going to bed, quetiapine may be mildly sedating and is felt to be the safest of the antipsychotics used in Parkinson’s.
  • This is often the first choice for providers given its relative safety and ease of use.


  • Evidence has proven that clozapine (Clozaril) may be effective in improving hallucinations and delusions in PD. However, due to a rare, yet serious side effect known as agranulocytosis ― a reduction in white blood cells that interferes with the body's ability to fight infection ― there is a tendency use this medication only if quetiapine is not tolerated or effective.
  • Anyone who takes clozapine is required to get weekly blood tests for the first six months and then every two weeks to monitor white blood cell levels thereafter.


  • Pimavanserin was approved by the U.S. Food and Drug Administration (FDA) in 2016 specifically for the treatment of Parkinson's disease psychosis.
  • Unlike other antipsychotics, it does not block dopamine. It is a selective serotonin inverse agonist, meaning it targets serotonin receptors.

For more information relating to Pimavanserin, please see Pimavanserin Practice Based Recommendations, by Rajesh Pahwa (University of Kansas Medical Center, a Parkinson’s Foundation Center of Excellence), Thomas Davis (Vanderbilt University Medical Center, a Parkinson’s Foundation Center of Excellence) and Kelly E Lyons (University of Kansas Medical Center).

Risperidone and Olanzapine

  • Risperidone (Risperdal®) and olanzapine (Zyprexa®) are two additional atypical antipsychotic agents.
  • Unlike pimavanserin, clozapine and quetiapine, these drugs may carry a greater risk of aggravating PD symptoms.

The treatment goal for each step throughout this process is to achieve a healthy balance between PD symptom control and management of hallucinations or delusions.

*It is important to familiarize yourself with antipsychotic medications as many can worsen motor symptoms and should not be prescribed for people with PD. Some of these medications, such as haloperidol (Haldol), are commonly prescribed in the hospital setting for patients who are agitated or anxious. Treating clinicians should be aware that certain antipsychotic medications can make the person with PDs condition worse.

Treating Psychosis Related to Delirium and Dementia

It is important to tell your family and doctor if you or your loved one is experiencing any symptoms of delirium or dementia. The doctor will review your health status and medications and come up with a treatment plan if needed.

Treating Psychosis related to Delirium

An acute medical condition generally causes delirium. Symptoms should improve once the underlying condition is treated. Additional measures (commonly performed in a hospital or inpatient setting) are sometimes necessary to reduce unsafe and problematic behavior.

Medications can be prescribed to calm an agitated or aggressive patient.

  • Although medications can help, they can also produce serious side effects in elderly individuals.
  • Two medications frequently used include lorazepam (Ativan®) and haloperidol (Haldol®). Quetiapine (Seroquel) could also be beneficial. Haloperidol (Haldol) should be avoided in people with Parkinson’s when possible.
  • In addition to medications, some facilities use temporary physical restraints. This is a controversial issue that should be closely monitored by family.

Treating Psychosis related to Dementia

Acetylcholinesterase inhibitors are medications used to treat memory impairment. They are commonly prescribed early in the management of dementia and include donepezil (Aricept ®) and rivastigmine (Exelon ®).

  • Through research and clinical observations, it has been found that these medications may also be beneficial in treating some forms of psychosis.
  • If not already prescribed, acetylcholinesterase inhibitors should be considered.
  • In addition, antipsychotic therapy may also be necessary for treating dementia with psychosis. Pimavanerin (FDA-approved in 2016 for treatment of PD psychosis) is available through specialty pharmacies.
  • Quetiapine and clozapine are considered the best antipsychotic medications for people with PD.

Page reviewed by Dr. Chauncey Spears, Movement Disorders Fellow at the University of Florida, a Parkinson’s Foundation Center of Excellence.

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