No laboratory test can diagnose schizophrenia. Instead, doctors typically make a diagnosis based on symptoms.

In some cases, doctors may perform additional tests to rule out other causes of symptoms, such as a brain injury or infection.

It is important for people to give a complete history of their symptoms when being evaluated for schizophrenia. The Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR) requires that symptoms be present for at least 6 months.

If a person has symptoms that last under that, a doctor might instead diagnose schizophreniform disorder.

Read on to learn more about how schizophrenia is diagnosed, lab tests, and when to contact a doctor.

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Healthcare professionals diagnose schizophrenia based on a person’s symptoms.

When evaluating an individual, a doctor will look for positive symptoms. These are symptoms that should not be present in a person without schizophrenia, such as hallucinations. A doctor will also look for negative symptoms, such as flat affect.

The DSM-5-TR, which healthcare professionals in the United States usually use, lists the following diagnostic criteria. A person must have two or more of the following:

  • hallucinations
  • delusions
  • disorganized or catatonic behavior
  • negative symptoms, such as the inability to feel pleasure
  • disorganized speech

These symptoms must disrupt daily life or relationships and be present for at least 6 months.

The International Classification of Diseases (ICD-10) requires that a person must have one or more of the following symptoms for at least 1 month:

  • delusions of influence, passivity, or control
  • a hallucination of voices that offer ongoing commentary
  • culturally inappropriate or unlikely delusions
  • disordered thinking, such as thought insertion or broadcasting one’s thoughts to others

Alternatively, a person must have two of the following symptoms for 1 month or longer:

  • persistent hallucinations in any form, such as auditory or visual hallucinations, as well as delusions
  • catatonic state
  • disordered thoughts that cause incoherent language or the invention of words
  • negative symptoms, such as lack of emotion or a flat affect
  • significant, ongoing changes in behavior that cause social withdrawal or the inability to feel happiness

Learn more about the signs and symptoms of schizophrenia.

No lab test can diagnose schizophrenia. Instead, schizophrenia testing may begin with a differential diagnosis. This is the process by which doctors assess how likely various diagnoses are and rule out possible causes.

Depending on a person’s history, a doctor may recommend certain tests. For example, a person who was recently in a car accident might need testing for a traumatic brain injury.

Some tests a doctor may recommend include:

  • blood tests to look for signs of infections or electrolyte imbalances, as well as to test for conditions that may cause mental health symptoms
  • urine tests for drugs that may induce symptoms of psychosis
  • tests of thyroid function
  • brain imaging scans, such as MRI or CT

If these tests do not uncover a condition that better explains symptoms, a doctor will assess whether a person has a psychiatric condition, including schizophrenia. They may assess for signs of other diagnoses, such as depression.

This process involves asking questions about a person’s history to better understand their symptoms.

Sometimes, doctors use validated scales. For example, they might use the Beck Depression Inventory to assess whether a person has depression instead of schizophrenia.

Diagnosing schizophrenia can be a challenge. This is because people with schizophrenia often have false beliefs and may not realize these beliefs are a symptom of schizophrenia.

A person should reach out to a doctor if:

  • loved ones express concern about their beliefs or behaviors
  • they have trouble keeping a job or maintaining relationships
  • they feel very anxious or upset about people or things others appear not to experience or worry about

Medication can help treat schizophrenia. Psychotherapy can help a person learn to manage their diagnosis. However, treatment may involve some trial and error.

People may worry about changes to their personalities or experiences. Most antipsychotic drugs cause significant side effects. This can affect how well a person follows treatment.

Social support can increase a person’s willingness to pursue and stick with treatment. Supportive friends and family may also help a person cope with the side effects of treatment, as well as the challenges of living with schizophrenia.

Some additional ways to get support include:

  • finding a therapist who specializes in schizophrenia
  • joining an online or in-person support group
  • learning as much about schizophrenia as possible
  • learning how to advocate for oneself, including learning about the rights of people with mental illness
  • talking with a healthcare professional if treatment side effects feel intolerable, and advocating for a treatment change
  • finding ways to manage stress, which can improve health and reduce symptoms

The National Alliance on Mental Illness (NAMI) can be a helpful resource.

Schizophrenia can affect many aspects of a person’s life, sense of self, and relationships. It is treatable, but treatment requires an accurate diagnosis.

People who think they might have schizophrenia can talk with a mental health professional to start the diagnostic process. It may also be helpful to talk with a mental health professional even if a person does not think they have the condition, but loved ones have expressed concern for their well-being.