Delusions and Delusional Disorder

Medically Reviewed by Smitha Bhandari, MD on January 12, 2023
7 min read

Delusional disorder, previously called paranoid disorder, is a type of serious mental illness called a psychotic disorder. People who have it can’t tell what’s real from what is imagined.

Delusions are the main symptom of delusional disorder. They’re unshakable beliefs in something that isn’t true or based on reality. But that doesn’t mean they’re completely unrealistic. Delusional disorder involves delusions that aren’t bizarre, having to do with situations that could happen in real life, like being followed, poisoned, deceived, conspired against, or loved from a distance. These delusions usually involve mistaken perceptions or experiences. But in reality, the situations are either not true at all or highly exaggerated.

A bizarre delusion, by contrast, is something that could never happen in real life, such as being cloned by aliens or having your thoughts broadcast on TV. A person who has such thoughts might be considered delusional with bizarre-type delusions.

People with delusional disorder often can continue to socialize and function normally, apart from the subject of their delusion, and generally do not behave in an obviously odd or bizarre manner. This is unlike people with other psychotic disorders, who also might have delusions as a symptom of their disorder. But in some cases, people with delusional disorder might become so preoccupied with their delusions that their lives are disrupted.

Although delusions might be a symptom of more common disorders, such as schizophrenia, delusional disorder itself is rather rare. Delusional disorder most often happens in middle to late life and is slightly more common in women than in men.

The types are based on the main theme of the delusion:

  • Erotomanic: The person believes someone is in love with them and might try to contact that person. Often it’s someone important or famous. This can lead to stalking behavior.
  • Grandiose: This person has an over-inflated sense of worth, power, knowledge, or identity. They could believe they have a great talent or made an important discovery.
  • Jealous: A person with this type believes their spouse or sexual partner is unfaithful.
  • Persecutory: Someone who has this believes they (or someone close to them) are being mistreated, or that someone is spying on them or planning to harm them. They might make repeated complaints to legal authorities.
  • Somatic: They believe they have a physical defect or medical problem.
  • Mixed: These people have two or more of the types of delusions listed above.


They usually include:

  • Non-bizarre delusions -- these are the most obvious symptom
  • Irritable, angry, or low mood
  • Hallucinations (seeing, hearing, or feeling things that aren’t really there) related to the delusion. For example, someone who believes they have an odor problem might smell a bad odor.


As with many other psychotic disorders, the exact cause of delusional disorder is not yet known. But researchers are looking at the role of genetic, biological, environmental, or psychological factors that make it more likely.

  • Genetic: The fact that delusional disorder is more common in people who have family members with delusional disorder or schizophrenia suggests genes may be involved. It is believed that, as with other mental disorders, a tendency to have delusional disorder might be passed on from parents to their children.
  • Biological: Researchers are studying how delusional disorders might happen when parts of the brain aren’t normal. Abnormal brain regions that control perception and thinking may be linked to the delusional symptoms.
  • Environmental/psychological: Evidence suggests that stress can trigger delusional disorder. Alcohol and drug abuse also might contribute to it. People who tend to be isolated, such as immigrants or those with poor sight and hearing, appear to be more likely to have delusional disorder.


If you have symptoms of delusional disorder, your doctor will likely give you a complete medical history and physical exam. Although there are no lab tests to specifically diagnose delusional disorder, the doctor might use diagnostic tests, such as imaging studies or blood tests, to rule out physical illness as the cause of the symptoms. These include:

  • Alzheimer’s disease
  • Epilepsy
  • Obsessive-compulsive disorder
  • Delirium
  • Other schizophrenia spectrum disorders

If the doctor finds no physical reason for the symptoms, they might refer the person to a psychiatrist or psychologist, health care professionals trained to diagnose and treat mental illnesses. They’ll use interview and assessment tools to evaluate the person for a psychotic disorder.

The doctor or therapist bases the diagnosis on the person's symptoms and their own observation of the person's attitude and behavior. They’ll decide if the symptoms point to a disorder.

A diagnosis of delusional disorder is made if:

  • The person has one or more delusions that last a month or longer
  • The person has never been diagnosed with schizophrenia; hallucinations, if they have them, are related to the themes of their delusions.
  • Apart from the delusions and its effects, their life isn’t really affected. Other behavior isn’t bizarre or odd.
  • Manic or major depressive episodes, if they’ve happened, have been brief, when compared with the delusions.
  • There isn’t another mental disorder, medication, or medical condition to blame.


Treatment most often includes medication and psychotherapy (a type of counseling). Delusional disorder can be very difficult to treat, in part because those who have it often have poor insight and do not know there’s a psychiatric problem. Studies show that close to half of patients treated with antipsychotic medications show at least partial improvement.

The primary medications used to attempt to treat delusional disorder are called antipsychotics. Drugs used include:

Other medications: Sedatives and antidepressants might also be used to treat anxiety or mood symptoms if they happen with delusional disorder. Tranquilizers might be used if the person has a very high level of anxiety or problems sleeping. Antidepressants might be used to treat depression, which often happens in people with delusional disorder

Psychotherapy can also be helpful, along with medications, as a way to help people better manage and cope with the stresses related to their delusional beliefs and its impact on their lives. Psychotherapies that may be helpful in delusional disorder include:

  • Individual psychotherapy can help the person recognize and correct the thinking that has become distorted.
  • Cognitive behavioral therapy (CBT) can help the person learn to recognize and change thought patterns and behaviors that lead to troublesome feelings.
  • Family therapy can help families deal with or support a loved one who has delusional disorder.

People with severe symptoms or who are at risk of hurting themselves or others might need to be hospitalized until the condition is stabilized.


  • People with delusional disorder might become depressed, often as the result of difficulties associated with the delusions.
  • Acting on the delusions also can lead to violence or legal problems. For example, a person with an erotomanic delusion who stalks or harasses the object of the delusion could be arrested.
  • Also, people with this disorder can become alienated from others, especially if their delusions interfere with or damage their relationships.


It varies, depending on the person, the type of delusional disorder, and the person's life circumstances, including the presence of support and a willingness to stick with treatment.

Delusional disorder is typically a chronic (ongoing) condition, but when properly treated, many people can find relief from their symptoms. Some recover completely, while others have bouts of delusional beliefs with periods of remission (lack of symptoms).

Unfortunately, many people with this disorder don’t seek help. It’s often hard for people with a mental disorder to know they aren’t well. Or they may credit their symptoms to other things, like the environment. They also might be too embarrassed or afraid to seek treatment. Without treatment, delusional disorder can be a lifelong illness.

There’s no known way to prevent delusional disorder. But early diagnosis and treatment can help lessen the disruption to the person's life, family, and friendships.

Show Sources


Intelihealth: "Delusional Disorder." "Delusional."

Medscape: "Delusional Disorder."

Diagnostic and Statistical Manual of Mental Disorders IV: "Delusional Disorder."

UpToDate: “Delusional disorder,” “Schizophrenia in adults: Clinical manifestations, course, assessment, and diagnosis.”

Merck Manuals: “Delusional Disorder.”

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