Schizophrenia and Substance Use: Signs Families Should Know and Treatment

Written by the medical team at Day One Rehabilitation Center, Nakhon Nayok, Thailand · Medically reviewed by Dr. Pichayut Kasemphakdeephong (Psychiatrist)

Schizophrenia is a psychiatric condition that affects thought, perception, mood, and daily life. Those affected may hear voices that others don’t hear, feel paranoid that people are following or trying to harm them, believe things that don’t match reality, speak or think in a confused way, withdraw from others, or experience a decline in their ability to study and work.

When schizophrenia occurs alongside substance use, the problem becomes more complex, because some substances can trigger hearing voices, paranoia, restlessness, and changed behavior. At the same time, some people with schizophrenia may use substances to cope with stress, loneliness, insomnia, or the discomfort caused by their own symptoms.

For families, this raises an important question: is what they’re seeing schizophrenia, a symptom of drug use, or both problems occurring together? Distinguishing the cause shouldn’t rely on guessing from behavior over a short period — it requires looking at the type of substance, the timing of use and cessation, prior symptom history, and monitoring symptoms after the substance’s effects wear off and during withdrawal, because this information affects the treatment approach.

What Are the Symptoms of Schizophrenia, and How Do They Differ From Drug-Induced Symptoms?

Schizophrenia is a condition involving continuous or recurring psychotic symptoms, and it usually affects a person’s ability to function in life. This doesn’t mean someone with schizophrenia will have severe symptoms all the time — many people in treatment can control their symptoms and return to a better quality of life with continuous treatment.

Symptoms families may notice include:

Hearing voices or other sounds that people nearby don’t hear
Feeling that someone is following, watching, or trying to harm them
Believing that someone is sending them specific messages or signals
Speaking in a rambling way or connecting ideas in ways that are hard for others to follow
A clear change in behavior from before
Withdrawing, talking less, and reducing social interaction
Losing interest in activities they used to enjoy
Showing less emotion or appearing more indifferent
A decline in personal hygiene and daily routine
Worsening performance at school or work
Problems with concentration, planning, or managing daily life

However, hearing voices and paranoia don’t always mean someone has schizophrenia. Yaba, ice, cannabis, and certain other psychoactive substances can cause psychotic symptoms, especially when used in large amounts, used continuously, or when pre-existing risk factors are present.

In some people, symptoms appear clearly during substance use and improve after stopping. But others may have symptoms that continue after the substance’s effects have worn off, or may be found to have a pre-existing psychiatric condition alongside substance use. It’s therefore wrong to conclude either “it’s just the drug, it’ll go away” or “it’s definitely schizophrenia” without proper assessment.

How Can Substance Use Make Schizophrenia Symptoms Worse?

For people who already have schizophrenia, substance use can make symptoms harder to control. Some substances stimulate brain activity, causing insomnia, restlessness, paranoia, or hallucinations, while other substances impair decision-making and behavioral control.

Yaba and ice are substances that require particular caution, because they can trigger paranoia, hearing voices, and thinking that doesn’t match reality. Sleep deprivation from continued substance use makes psychotic symptoms even more severe.

Cannabis is another substance that deserves attention, especially for people at risk of psychotic symptoms or who have had them before. Cannabis is not a treatment for schizophrenia, and in some people it may be associated with triggering or worsening psychotic symptoms.

Alcohol, while producing effects different from stimulants, can impair decision-making, disrupt sleep, lead to inconsistent medication use, and make overall treatment more complicated.

When schizophrenia and substance addiction occur together, problems that may arise include:

More frequent relapses of hearing voices or paranoia
Inconsistent use of psychiatric medication
Irregular sleep
Reduced self-care
Conflict with family
Impact on school or work
Returning to substance use after symptoms improve
Needing repeated hospital admissions due to relapses

Psychiatric symptoms therefore shouldn’t be treated alone without addressing substance use, and substance addiction shouldn’t be treated while overlooking schizophrenia, because the two problems can affect each other throughout the recovery process.

How Is Schizophrenia Occurring Alongside Substance Addiction Treated?

Treatment should begin with a thorough assessment of what substance is used, how often, when it was last used, whether psychotic symptoms began before or after substance use, whether symptoms have occurred during periods without substance use, and whether the person has ever been diagnosed or treated psychiatrically before.

Assess Psychotic Symptoms and Safety

During periods of severe symptoms, the person in treatment may not be able to distinguish whether what they hear or believe matches reality. Families shouldn’t try to win the argument by saying “no one is following you” or “you’re just imagining it,” because this can increase distrust and conflict.

It’s better to speak in a calm tone and listen to the person’s feelings without necessarily confirming that the belief is true — for example: “I understand you feel very scared right now. We want to help you feel safer.”

If the person is extremely confused, unable to control themselves, not eating or drinking, unable to care for themselves, engaging in risky behavior, or having thoughts or behaviors of self-harm, they should receive a medical evaluation as soon as possible.

Treat Schizophrenia Continuously With Medication

Antipsychotic medication is an important part of treating schizophrenia, helping to reduce hearing voices, paranoia, thinking that doesn’t match reality, and other psychotic symptoms. Choosing and adjusting medication must be considered individually based on symptoms, side effects, existing conditions, and treatment history.

A problem commonly seen in people who also use substances is inconsistent medication use. Some stop taking medication when they feel better, some forget to take it because of substance use or disrupted sleep schedules, and some don’t accept that they have a problem — all of which can lead to relapse.

For people who struggle with taking medication every day, a psychiatrist may consider a long-acting injectable antipsychotic for some patients to reduce the problem of missed doses, but this must be considered based on what’s appropriate for each individual.

Psychiatric medication should never be stopped or reduced on one’s own when symptoms improve. Adjusting medication should be done together with a psychiatrist.

Treat Substance Addiction at the Same Time

If psychiatric symptoms improve with treatment but the person returns to using yaba or ice, paranoia and hearing voices can return. Conversely, if someone tries to stop using substances without treating their psychiatric symptoms, they may still suffer from those symptoms and go back to using substances to try to manage their own feelings.

Treatment should therefore help the person understand the relationship between the substance and their symptoms, identify triggers that lead them back to substance use, practice managing cravings, and build ways of coping with stress that don’t rely on the substance.

Motivational conversations are useful, especially for people who don’t yet see substance use as a problem. The goal isn’t to force immediate acceptance, but to help the person see the difference between the life they want and the consequences of substance use, gradually building motivation to change.

Restore Sleep, Routine, and Daily Life

Treatment doesn’t end when hearing voices or paranoia decrease. People who have gone through a period of relapse may still have problems with motivation, concentration, socializing, self-care, or confidence about returning to school and work.

Building routine is therefore part of recovery — such as sleeping and waking at consistent times, taking medication consistently, exercising, maintaining hygiene, engaging in purposeful activities, and gradually returning to responsibilities as they become ready.

Families should learn the warning signs of both a relapse of the condition and a return to substance use, so they can seek help from the earliest stage.

A Family Member Has Schizophrenia and Uses Drugs, but Won’t Accept Treatment — What Should You Do?

One of the most difficult situations for families is when the person with symptoms won’t accept that they have a problem. Some believe they aren’t ill, some think the family is trying to control them, while others accept that they have symptoms but don’t see that substance use is connected to those symptoms.

Saying “you have to accept first that you’re sick” or trying to force acceptance of everything at once can lead to more resistance. It’s better to start with the problem the person themselves recognizes and wants to solve — such as insomnia, stress, arguing with people at home, having no money, or feeling constantly disturbed — and then connect that to getting an evaluation.

The family might say: “I’ve noticed you haven’t been sleeping well lately and you look very stressed. We’d like to get someone to help with the sleep and stress issues first.” Starting from what the person themselves values may open the door to cooperation more than arguing over the name of the condition.

At the same time, the family should maintain clear boundaries — not funding money that goes toward buying substances, not helping to cover up the harmful consequences of substance use, and not allowing unsafe behavior to continue without intervention.

If the person isn’t ready for treatment yet, the family can consult the treatment team first, to plan how to talk with them, assess the level of risk, and find an appropriate way to bring them into treatment.

Outpatient or Residential Treatment — Which Is Right for Schizophrenia and Substance Use?

Not everyone with schizophrenia or a history of substance use needs residential treatment. The choice of treatment format should be based on the severity of symptoms, safety, ability to stop using the substance, consistency in taking medication, environment, and the family’s readiness.

For people whose psychiatric symptoms are stable, with no emergency, and who can travel for treatment and follow up consistently, outpatient assessment can begin at Piti Clinic, our outpatient mental-health clinic in Bangkok (Pradiphat Road, Saphan Khwai), to assess psychiatric symptoms, substance use, sleep, medication, and co-occurring problems, before planning appropriate treatment.

If the person with symptoms hasn’t yet accepted that they have a problem, the family can come in for a consultation first, to help assess the situation and plan a communication approach, without needing to wait for the person to accept the terms “schizophrenia” or “addiction” before seeking help.

On the other hand, if there is repeated substance use, frequent relapse of psychiatric symptoms, inconsistent medication use, an inability to stop access to the substance in the same environment, or a need for close monitoring, residential treatment may be more appropriate.

If symptoms are severe enough to become an emergency — such as extreme confusion, an inability to care for oneself, potentially dangerous behavior, or thoughts and behaviors of self-harm — an emergency evaluation should be sought immediately, rather than waiting for a scheduled outpatient appointment.

Treating Schizophrenia and Substance Addiction at Day One Rehabilitation Center

People with co-occurring schizophrenia and substance addiction need to be assessed for both problems — not just choosing to treat schizophrenia or the addiction alone.

At Day One Rehabilitation Center, residential care allows the treatment team to continuously monitor psychiatric symptoms, sleep, medication use, withdrawal symptoms, and daily behavior. A psychiatrist can assess symptoms and adjust medication as appropriate, while the person in treatment receives therapy for substance use, craving management, relapse prevention, and routine rebuilding.

An environment with no access to substances in the early stage also helps clarify, once the effects and symptoms of the substance have worn off, which psychiatric symptoms remain — important information for planning the next stage of treatment.

The goal of treatment isn’t only to reduce hearing voices or paranoia — it’s to help the person in treatment return to taking medication consistently, sleep on a regular schedule, care for themselves, understand the relationship between the substance and their own symptoms, and have a relapse-prevention plan for after leaving treatment.

Frequently Asked Questions About Schizophrenia and Substance Use

Do hearing voices and paranoia after using drugs mean someone has schizophrenia?

Not necessarily. Many substances can cause psychotic symptoms. Diagnosis must consider the relationship between the symptoms and substance use, how long the symptoms continue after stopping the substance, prior symptom history, and other information together.

Can yaba and ice cause schizophrenia?

Yaba and ice can cause psychotic symptoms such as hearing voices, paranoia, and thinking that doesn’t match reality. But having symptoms caused by a substance doesn’t mean everyone will develop schizophrenia. Distinguishing between the two conditions requires assessment and monitoring of symptoms after stopping the substance.

Can someone with schizophrenia use cannabis?

People with schizophrenia, or who have previously had psychotic symptoms, should avoid cannabis, because it can trigger a relapse of psychotic symptoms or make them harder to control in some people.

Once someone stops using drugs, will hearing voices go away?

It depends on the cause. If the symptoms are related to the effects of the substance, they may improve after stopping the substance and receiving care. But if schizophrenia or another psychiatric condition is also present, the symptoms may persist and require ongoing treatment. Stopping the substance alone shouldn’t be used as a way to self-test or self-diagnose.

Does schizophrenia require taking medication for life?

Treatment duration varies from person to person and depends on the number of relapses, severity, response to medication, and other risk factors. Stopping medication should be a decision made together with a psychiatrist — never stopped on one’s own just because symptoms feel better.

If the patient won’t accept that they have schizophrenia, how do you get them into treatment?

There’s no need to start by forcing them to accept the name of the condition. You can start by talking about what the person themselves is suffering from — such as not being able to sleep, stress, paranoia, or problems with people around them — and then invite them to get an evaluation to help solve that problem first. If they still refuse, the family can consult the treatment team to plan how to communicate.

Can schizophrenia with co-occurring substance addiction be treated?

Yes, it can be treated and the symptoms controlled. Treatment usually needs to address both schizophrenia and substance use together, including taking medication consistently, therapy, rebuilding routines, and relapse prevention. Continuous treatment increases the chance that the person in treatment can return to a better quality of life.

Does schizophrenia require residential treatment?

Not for everyone. If symptoms are stable, there’s no emergency, and treatment can be followed up consistently, outpatient treatment can begin at Piti Clinic in Bangkok. But if there is co-occurring substance addiction, uncontrolled substance use, repeated relapse, inconsistent medication use, or an environment that prevents continuous treatment, residential treatment at Day One Rehabilitation Center may be worth considering.

Schizophrenia and Substance Addiction Should Be Treated Together

When a family member has hearing voices, paranoia, changed behavior, and a history of substance use, the important thing isn’t to rush to conclude “it’s the drug” or “it’s the illness” — it’s to bring them into a proper evaluation, to see how the two problems are related to each other.

Schizophrenia can be treated and its symptoms controlled, and substance addiction can be recovered from as well. Addressing both at the same time helps close the gap where psychiatric symptoms relapse and lead back to substance use, or where a person stops using the substance for a while but psychiatric symptoms remain, preventing continuous recovery.

For people whose symptoms are stable, starting with an outpatient assessment can help identify the problem and plan treatment early on. For those with schizophrenia occurring alongside complex substance use, residential treatment can help create an environment that supports stopping the substance, monitoring symptoms, and continuous recovery.

Families don’t need to wait for the person to accept every problem first. Listening without deepening the conflict, watching for danger signs, and seeking guidance from the treatment team early on can be the starting point of treatment.