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Schizophrenia and Substance Abuse

Substance abuse can be a co-occuring issue among those diagnosed with schizophrenia. Roughly 50 percent of individuals suffering from schizophrenia struggle with drug and alcohol abuse.

Some people who abuse drugs may display symptoms similar to those of schizophrenia, which may lead people to think that those with schizophrenia may be “high on drugs.” This can, at times, make it difficult to diagnose schizophrenia or co-occurring disorders.

While substance abuse does not cause schizophrenia, it can act as an environmental trigger.  Using drugs such as cocaine, amphetamines, and marijuana can also increase schizophrenic symptoms and worsen their severity. Also, people who have schizophrenia often abuse alcohol or drugs, and may experience particularly bad reactions to certain drugs.

Research is mixed as to the cause and correlation between schizophrenia and substance abuse. Some researches believe that people use drugs or alcohol to self-medicate when experiencing unpleasant symptoms or the side effects of antipsychotic medication. Others believe that people predisposed to develop schizophrenia are also at risk for substance use. There is also evidence that environmental factors can play a role, as a majority of people with schizophrenia and substance abuse experienced a significant trauma earlier in life.

Schizophrenic people commonly abuse substances including nicotine, alcohol, cocaine, and cannabis, and they experience more cognitive impairment, more intense psychosis, and, thus, an increased need of emergency services. They are also more prone to legal troubles and incarceration.

The most common form of substance use disorder in people with schizophrenia is nicotine dependence due to smoking. While the prevalence of smoking in the U.S. population is about 25 percent to 30 percent, the prevalence among people with schizophrenia is approximately three times as high.  People with schizophrenia who smoke are at increased risk of experiencing delusions, hallucinations, and disjointed speech. They also, as a result, would require higher dosages of antipsychotic medications. Since smoking can interfere with the response to antipsychotic drugs, studies have found that schizophrenia patients who smoke need higher doses of antipsychotic medication.

It is vital that both disorders are treated simultaneously.  If a person stops substance use without being connected to proper medication and treatment for mental health, they are likely to relapse. Likewise, if a person is given mental health treatment without addressing substance abuse, they may stop treatment. This is why it’s important to treat both disorders at concurrently.


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Addiction Center. (2018.) What is Schizophrenia? Retrieved from on May 29, 2018.

PSYCOM. (2018.) Schizophrenia and Substance Abuse Retrieved from on May 29, 2018.

Schizophrenia and Substance Abuse

Amy Carmosino

Amy Carmosino has been a freelance editor and writer for Pysch Central since 2016.

APA Reference
Carmosino, A. (2020). Schizophrenia and Substance Abuse. Psych Central. Retrieved on December 3, 2020, from
Scientifically Reviewed
Last updated: 17 Jan 2020 (Originally: 17 May 2016)
Last reviewed: By a member of our scientific advisory board on 17 Jan 2020
Published on Psych All rights reserved.