Schizophrenia is a disease of brain function which affects about 1% of the population.1 Symptoms vary between individuals and can affect sufferers’ thoughts, feelings and actions.

Symptoms of schizophrenia

Disease burdens

For the patient

Schizophrenia is a disease of brain function which affects about 1% of the population.1 Symptoms vary between individuals and can affect sufferers’ thoughts, feelings and actions. In general, symptoms take the following forms:1

  • Separation from reality
  • Delusions
  • Hallucinations
  • Emotional dysregulation
  • Disorganised behaviour

Schizophrenia typically progresses in cycles of relapses and remissions. Patients often suffer impaired social relationships leading to isolation, impaired mental function, inability to function at work and poor health, all contributing to a reduced quality of life (QoL).1 An estimated 25-50% of patients attempt suicide and 10% achieve it.2

For caregivers

The impact of schizophrenia goes beyond the individual with the disease. Caregivers, who are often family members, also suffer consequences of a dependent with schizophrenia:1

  • Parents: 41% of schizophrenia patients live with their parents
  • Brothers and sisters: 12% of schizophrenia patients are cared for by their siblings
  • Spouses/partners: 7% of patients are cared for by their spouses/partners

The types of burden suffered by carers include:1

  • Work overload
  • Poor sleep
  • Little free time for leisure activities and socialising
  • Financial pressures
  • Environmental burden: stigmatisation and social isolation by neighbours and others

Many schizophrenia patients need 24/7 care, so it is not surprising that reduced QoL for the patient is associated with reduced QoL for the caregiver.1

Positive and negative symptoms3

The symptoms of schizophrenia are usually classified into:

Positive symptoms

Any change in behaviour or thoughts, such as hallucinations or delusions

Positive symptoms of schizophrenia

Hallucinations are where someone sees, hears, smells, tastes or feels things that do not exist outside their mind. One of the most common hallucinations is hearing voices.

Hallucinations are very real to the person experiencing them, even though people around them cannot hear the voices or experience the sensations.

Research using brain-scanning equipment illustrates changes in the speech area of brains in individuals with schizophrenia when they hear voices. These studies show the experience of hearing voices as a real one, as if the brain mistakes thoughts for real voices.

Some people describe the voices they hear as friendly and pleasant, but more often they're rude, critical, abusive or annoying.

The voices might describe activities taking place, discuss the hearer's thoughts and behaviour, give instructions, or talk directly to the person. Voices may come from different places or one place, such as the television.

A delusion is a belief held with complete conviction, even though it's based on a mistaken, strange or unrealistic view. It may affect the way the person behaves. Delusions can begin suddenly or may develop over weeks or months.

Some people may develop a delusional idea to explain a hallucination they're having. For example, if they have heard voices describing their actions, they may have a delusion that someone is monitoring their actions.

Someone experiencing a paranoid delusion may believe they're being harassed or persecuted. They may believe they're being chased, followed, watched, plotted against or poisoned, often by a family member or friend.

Some people who experience delusions find different meanings in everyday events or occurrences.

They may believe people on TV or in newspaper articles are communicating messages to them alone, or that there are hidden messages in the colours of cars passing on the street.

People experiencing psychosis may often have trouble keeping track of their thoughts and conversations.

Some people can find it hard to concentrate and will drift from one idea to another. They may have trouble reading newspaper articles or watching a TV programme.

People sometimes describe their thoughts as "misty" or "hazy" when this is happening to them. Thoughts and speech may become jumbled or confused, making conversation difficult and hard for other people to understand.

A person's behaviour may become more disorganised and unpredictable.

Some people describe their thoughts as being controlled by someone else, that their thoughts are not their own, or that thoughts have been planted in their mind by someone else.

Another feeling is that thoughts are disappearing, as though someone is removing them from their mind.

Some people feel their body is being taken over and someone else is directing their movements and actions.

Negative symptoms

Where people appear to withdraw from the world around them, take no interest in everyday social interactions, and often appear emotionless and flat

Negative symptoms of schizophrenia

The negative symptoms of schizophrenia can often appear several years before somebody experiences their first acute schizophrenic episode.

These initial negative symptoms are often referred to as the prodromal period of schizophrenia.

Symptoms during the prodromal period usually appear gradually and slowly get worse.

They include the person becoming more socially withdrawn and increasingly not caring about their appearance and personal hygiene.

It can be difficult to tell whether the symptoms are part of the development of schizophrenia or caused by something else.

Negative symptoms experienced by people living with schizophrenia include (but are not limited to):

  • losing interest and motivation in life and activities, including relationships and sex
  • lack of concentration, not wanting to leave the house and changes in sleeping patterns
  • being less likely to initiate conversations and feeling uncomfortable with people or feeling there's nothing to say

The negative symptoms of schizophrenia can often lead to relationship problems with friends and family as they can sometimes be mistaken for deliberate laziness or rudeness.

  1. Millier A, Schmidt U, Angermeyer MC, Chauhan D, Murthy V, Toumi M, et al. Humanistic burden in schizophrenia: a literature review. J Psychiatr Res 2014; 54: 85-93.
  2. Stahl, S. 2013 Stahl's Essential Psychopharmacology - 4th Edition. Cambridge University Press.
  3. Schizophrenia, Symptoms. available at: https://www.nhs.uk/conditions/schizophrenia/symptoms/ (last accessed December 2025).

UK-CLZ-2025-00014 December 2025

This website is owned and managed by Viatris. This website is intended for UK healthcare professionals only.

The active ingredient and instructions for use are the same for Clozaril® and Clozapine Mylan. Any mention of Clozaril® would also apply to Clozapine Mylan. Clozaril® is indicated in treatment-resistant schizophrenic patients and in schizophrenia patients who have severe, untreatable neurological adverse reactions to other antipsychotic agents, including atypical antipsychotics.

Treatment resistance is defined as a lack of satisfactory clinical improvement despite the use of adequate doses of at least two different antipsychotic agents, including an atypical antipsychotic agent, prescribed for an adequate duration. Clozaril® is also indicated in psychotic disorders occurring during the course of Parkinson’s disease, in cases where standard treatment has failed.

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