Scientists believe schizophrenia may affect a person’s sense of smell or cause them to smell things that are not there, but not all studies into schizophrenia and smell support this.

Schizophrenia is a mental health condition that affects how a person thinks, feels, and behaves. The condition may also affect a person’s sense of smell or lead them to have hallucinations that include smelling things that are not there.

Symptoms of schizophrenia may make it difficult for a person to participate in daily activities. However, treatments are available that can help manage symptoms of the condition.

Effects of schizophrenia on smell

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Scientists believe schizophrenia may affect how well a person can identify a smell, or how they perceive a smell. This difficulty may significantly affect a person’s daily life.

Existing research

Researchers investigated these effects in a 2019 study, which compared sense of smell among people with:

• first episode psychosis
• chronic schizophrenia
• neither schizophrenia nor psychosis

The study results suggest those with chronic schizophrenia may have the most difficulty identifying pleasant smells. They may also have difficulty identifying neutral smells, but not unpleasant smells.

However, this study only involved a small number of participants and did not include people in the prodromal (early) phase of schizophrenia. The researchers recommend additional studies with larger numbers of people to confirm their findings.

Inconsistent findings

A 2023 review of existing research into olfactory dysfunction (a reduced or distorted ability to smell) and mental health conditions states that schizophrenia is one of several mental health conditions that could change smell identification and perception.

However, its authors cite contradictory research on this topic:

• Smell identification: Certain studies found people with schizophrenia could not identify smells well, while others found the condition had no effect on this ability.
• Smell perception: Some research suggests people with schizophrenia may find pleasant smells unpleasant, and vice versa, while other studies indicate a person with particular schizophrenia symptoms may find pleasant smells more pleasant.

In their conclusion, the review’s authors state that loss of the ability to identify smells might be an early sign of schizophrenia, and that people with strong “negative” schizophrenia symptoms often appeared to have a noticeably changed sense of smell. (Find more information about negative symptoms in the “Symptoms of schizophrenia” section below.)

However, they conclude that the overall evidence is still inconsistent.

Olfactory hallucinations in schizophrenia

People with schizophrenia may have several symptoms that affect how they experience the world, including hallucinations.

A hallucination is when a person experiences things that do not exist outside their mind. Hallucinations can affect any of a person’s five senses. This means a person with schizophrenia may smell things that are not there.

Doctors may refer to hallucinations involving smell as olfactory hallucinations or phantosmia. Several types of physical or mental health conditions can cause this symptom, including schizophrenia.

However, olfactory hallucinations with schizophrenia are rare.

People with phantosmia most commonly report  smelling burnt or smoky smells. They may also believe they smell gas or feces or experience smells that are:

• sweet
• fruity
• musty
• metallic
• rotten

Learn more about schizophrenia

• What are the different types of schizophrenia?
• Early signs of schizophrenia: What to look for
• What is the link between trauma and schizophrenia?
• Coping with schizophrenia: Tips and more
• Helping someone with schizophrenia: What to know

Other symptoms of schizophrenia

Schizophrenia symptoms may differTrusted Source from person to person. They can include:

• symptoms of psychosis, such as:
  • disruptions to thoughts and perceptions
  • difficulty recognizing what is and is not real
  • hallucinations
  • delusions (strong beliefs that are not true and may seem irrational to others)
  • thought disorder (ways of thinking that are unusual or illogical)
• negative symptoms, including:
  • loss of motivation
  • loss of interest in daily activities and things they used to enjoy
  • withdrawal from social life
  • difficulty showing emotions
  • difficulty functioning in their typical way
• cognitive symptoms, including problems with their:
  • attention
  • concentration
  • memory

Treatment for schizophrenia

Schizophrenia treatments includeTrusted Source:

• antipsychotic medications
• psychosocial treatments to help people manage their symptoms, including:
  • cognitive behavioral therapy (CBT)
  • behavioral skills training
  • supported employment
  • cognitive remediation interventions
• coordinated specialty care (CSC) programs, which are recovery-focused programs for people early stage schizophrenia
• treatment for drug and alcohol misuse, if needed
• community treatments

Education and support can also help family and friends learn how to support people with schizophrenia.

Read more about schizophrenia treatments.

Frequently asked questions

What are the five main symptoms of schizophrenia?

The main symptoms of schizophrenia include hallucinations and delusions. A person may also experience thought disorder, which involves confused or jumbled thoughts. This may cause their speech to become disorganized and hard to understand. Negative symptoms, such as loss of motivation, are also common.

What happens if schizophrenia goes untreated?

Untreated schizophrenia can make a person more to develop complications such as cognitive difficulties, social withdrawal, and an increased risk of suicidal thoughts and behaviors. Without treatment for schizophrenia, a person with the condition may also be more likely to develop physical health issues or substance use disorders.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

• Ask the tough question: “Are you considering suicide?”
• Listen to the person without judgment.
• Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
• Stay with the person until professional help arrives.
• Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

Summary

People with schizophrenia may hallucinate by smelling things that are not there, such as burnt or smoky smells that are not real.

Scientists believe schizophrenia may also affect how well a person can identify and perceive different smells (how pleasant or unpleasant they find them). However, existing research into schizophrenia’s effect on a person’s sense of smell shows different results.

Other symptoms of schizophrenia include changes to a person’s behavior and thoughts, such as delusions and disorganized speech. People can also experience negative symptoms, appearing withdrawn, uninterested, or emotionless.

Healthcare professionals can use several methods to treat schizophrenia, such as medication and therapy.