Delusions vs. Hallucinations: What Are the Differences?

Delusions are persistent, unshakable beliefs that are not based on reality. For instance, a person may believe that their thoughts are being controlled by aliens, or that black and red cars on the street are sending them coded messages only they can decipher.

Hallucinations, on the other hand, involve imaginary sensations that no one else can experience. For instance, a person may hear sounds or voices when no one else is in the room, or see spiders crawling across the wall.

Delusions and hallucinations are both distortions of reality, which can occur during a state known as psychosis, where a person may not be able to tell the difference between what’s real and what isn’t. Some health conditions, mental illnesses, and substances can cause psychosis.

For instance, a person may have the delusional belief that someone is trying to kill them and may have hallucinations where they hear threatening voices. Neither may be true in reality; however, they can feel very real to the person experiencing them and cause them to react or behave in unusual ways.

This article explores the types, causes, diagnosis, and treatment of delusions and hallucinations.

Types

There are multiple types of delusions and hallucinations that people may experience. Let's take a look at how they compare to one another.

Types of Delusions

These are some of the types of delusions a person may experience:

• Persecutory delusions: The person may believe that someone is spying on them, mistreating them, plotting against them, or trying to harm them. People who experience persecutory delusions may make frequent complaints to legal authorities. 
• Erotomanic delusions: The person may believe someone—often a celebrity—is in love with them. They may try to contact the person or even engage in behaviors such as stalking.
• Grandiose delusions: The person may believe that they are someone rich, important, powerful, famous, talented, or knowledgeable. For instance, they may believe they’ve made an important discovery.
• Jealous delusions: The person may believe that their partner is unfaithful to them.
• Somatic delusions: Due to somatic delusions, the person may believe that they have a medical problem or disability.
• Mixed delusions: The person may experience two or more types of delusions.

Types of Hallucinations

The different types of hallucinations involve the different senses:

• Auditory hallucinations: Hearing voices, music, footsteps, or other sounds that no one else can hear. These tend to be the most common types of hallucinations. The voices the person hears may be friendly, neutral, rude, or hostile.
• Visual hallucinations: Seeing people, patterns, lights, or objects that don’t exist. For instance, the person may see objects move around in ways they typically cannot.
• Olfactory hallucinations: Smelling things that no one else can smell. The person may attribute the odors to their surroundings or themselves.
• Gustatory hallucinations: Tasting things no one else can detect. For example, the person may find that food doesn’t taste the way it should, or they may be able to taste food they haven’t eaten. 
• Tactile or somatic hallucinations: Feeling sensations that are not real. The person may believe someone is tickling or pinching them, or feel like insects are crawling all over their skin.
• Multimodal hallucinations: The person may experience more than one type of hallucination simultaneously, making the experience feel very real to them. For instance, they may hear thunder rumbling, feel a draft on their face, and see the room start to fill up with water. 

Causes

Delusions and hallucinations are symptoms of psychosis that often stem from the same cause. Some of the potential causes of psychosis include:

• Alcohol and certain drugs, which can cause psychosis while the person is under the influence as well as during withdrawal
• Mental health conditions like schizophrenia, bipolar disorder, or severe depression
• Brain diseases like Huntington's disease and Parkinson’s disease
• Alzheimer’s disease and dementia 
• HIV and other infections, which can affect the brain
• Severe illnesses like kidney failure or liver failure
• Brain tumors and cysts
• Certain prescription medications like stimulants and steroids
• Epilepsy
• Stroke
• Fever
• Delirium

Diagnosis

If you or a loved one are experiencing either delusions or hallucinations, seek help immediately. You can contact a medical or mental healthcare provider who can offer a diagnosis or refer you to a specialist.

The diagnostic process may involve:

• Psychiatric testing and evaluation, to understand your symptoms, thoughts, and behaviors
• Blood tests, to check for medical conditions, infections, and hormonal or nutrient imbalances
• Drug screens, to check for the presence of substances in your system
• Imaging scans, to check for medical conditions and abnormalities

Treatment

Treatment for delusions and hallucinations can vary depending on the underlying cause, but it may involve:

• Hospitalization: If the person is having a severe psychotic episode or is at risk of harming themselves or others, they may have to be hospitalized until they’re stabilized.
• Antipsychotic medication: Antipsychotic medication can help reduce delusions and hallucinations. It can also promote clear thinking and help the person distinguish between what’s real and what isn’t. These medications work by blocking the effect of the neurotransmitter dopamine in the brain.
• Therapy: Cognitive behavioral therapy (CBT) can help people recognize delusions and hallucinations and help them control their reactions to them. For instance, the person may learn to understand that if no one else can see the ketchup bottle dancing on the table, it probably isn’t real. 
• Rehabilitation and support: People who experience psychosis may need rehabilitation to help them function independently, and may benefit from joining support groups, where they can interact with others who have had similar experiences.

A Word From Verywell

Delusions and hallucinations are both manifestations of psychosis. While it's easy to confuse them, it's important to remember that they are not the same thing. Delusions involve thinking patterns, thoughts, and beliefs that are not rooted in reality. Hallucinations involve sensory experiences that are not rooted in reality. Both may occur simultaneously, and have similar causes, diagnosis, and treatment.

It can be hard to watch a loved one experience delusions or hallucinations, particularly the first time. However, it’s important to help them get the treatment they need, to help reduce these occurrences.