How substances affect mental health
Alcohol and drugs change mood, sleep, thinking, and motivation. If you live with a mental health condition, substance use can make symptoms worse and treatment harder. Here is what the research shows, in plain language.
Many people use substances to cope with stress, anxiety, low mood, or trouble sleeping. In the short term, a substance can feel like relief. Over time, most substances do the opposite. They can deepen depression, increase anxiety, disturb sleep, cloud thinking, and raise the risk of psychosis and suicide.
Substance use can also change the brain in ways that make prescribed medications less effective and recovery slower. This page is not about blame or judgment. It is about giving you honest information so you can make informed choices about your health. If you use substances and struggle with your mental health, both deserve attention in your care, and it is safe to talk about both here.
Choose a substance below to read what research shows about its effects on mental and physical health. Every study listed links to its abstract on PubMed, a free public database from the U.S. National Library of Medicine.
Cannabis (Marijuana)
Linked to higher risk of psychosis, worse anxiety and depression in heavy users, and lasting effects on memory and motivation.
See the research →Alcohol
A depressant that worsens depression and anxiety over time, disrupts sleep, and damages the liver, heart, and brain.
See the research →Cocaine
Can trigger paranoia and psychosis, crash mood into depression after use, and strain the heart and blood vessels.
See the research →Methamphetamine
Strongly linked to psychosis that can persist for months, severe depression during withdrawal, and damage to teeth, skin, and the heart.
See the research →Opioids
Heroin, fentanyl, and misused prescription pain pills. High overdose risk, deepening depression, and severe withdrawal that keeps the cycle going.
See the research →Nicotine (Tobacco and Vaping)
Worsens anxiety and depression between uses, disrupts sleep, and remains a leading cause of preventable illness and death.
See the research →Benzodiazepines and Sedatives
Xanax, Valium, Klonopin, and sleep aids. Can rebound anxiety worse than before, impair memory, and cause dangerous withdrawal.
See the research →Hallucinogens
LSD, mushrooms, and PCP. Can trigger lasting psychosis or frightening flashbacks in vulnerable people, especially with heavy use.
See the research →MDMA (Ecstasy, Molly)
The days after use often bring low mood and anxiety. Heavy use is linked to lasting depression and memory problems.
See the research →Kratom
Marketed as natural but acts on opioid receptors. Can cause dependence, withdrawal, liver injury, and worsening mood.
See the research →Inhalants
Solvents, aerosols, and nitrites. Can cause sudden death from heart failure and lasting damage to the brain and nerves.
See the research →Cannabis (marijuana)
Cannabis is often seen as harmless, but research shows real mental health risks, especially with frequent use, high potency products, and use that starts in the teens. Heavy use is linked to higher risk of psychosis and schizophrenia, worse anxiety and depression, and problems with memory, attention, and motivation that can linger after stopping.
Physically, smoked cannabis irritates the lungs and airways. Regular heavy use can also cause a cycle of severe nausea and vomiting known as cannabinoid hyperemesis syndrome.
Research and further reading
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Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis
Marconi et al. · Schizophrenia Bulletin · 2016
People who used cannabis heavily were more likely to develop psychosis, and the more someone used, the higher the risk appeared to be.
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Gobbi et al. · JAMA Psychiatry · 2019
Teens who used cannabis were more likely to develop depression as young adults, were about half again as likely to have thoughts of suicide, and were more than three times as likely to attempt suicide. As an observational study it cannot prove cause.
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Kedzior et al. · BMC Psychiatry · 2014
Across 31 studies, people with anxiety disorders were more likely to use cannabis, and people who had used cannabis at the start of the studies showed a small increase in anxiety later on.
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Marijuana Use, Respiratory Symptoms, and Pulmonary Function: A Systematic Review and Meta-analysis
Ghasemiesfe et al. · Annals of Internal Medicine · 2018
Smoking cannabis was linked to more coughing, mucus, wheezing, and shortness of breath, although the studies did not prove lasting lung damage.
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Storck et al. · Heart · 2025
Cannabis use was linked to higher chances of heart attack, stroke, and death from heart disease, though many of the underlying studies had important quality limits.
Alcohol
Alcohol is a depressant. It may ease nerves for an hour, but as it wears off it disrupts sleep, increases next day anxiety, and over time deepens depression. Heavy drinking is strongly linked to depression, suicide risk, and alcohol induced mood and anxiety disorders that can look just like major depression or panic disorder.
The body pays a price too. Heavy alcohol use damages the liver, raises blood pressure, weakens the heart, increases cancer risk, and can cause lasting brain injury and memory loss.
Research and further reading
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Li et al. · Addiction · 2020
People with alcohol use disorders were 57 percent more likely to develop depressive symptoms later on.
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Alcohol use and death by suicide: A meta-analysis of 33 studies
Isaacs et al. · Suicide and Life-Threatening Behavior · 2022
Across more than 10 million people in 33 studies, alcohol use was linked to a 94 percent higher risk of dying by suicide.
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A meta-analysis of acute use of alcohol and the risk of suicide attempt
Borges et al. · Psychological Medicine · 2017
Drinking shortly before a suicide attempt was linked to much higher odds of making an attempt, with risk climbing as the amount of alcohol rose.
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Llamosas-Falcón et al. · Hepatology International · 2023
The more alcohol people drank, the higher their chances of developing serious liver scarring and dying from it, with no clearly safe amount identified.
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Wood et al. · The Lancet · 2018
Drinking more alcohol was linked to higher risks of stroke, heart failure, fatal high blood pressure disease, aortic aneurysm, and dying from any cause once drinking passed about 100 grams of alcohol per week.
Cocaine
Cocaine creates an intense short high followed by a crash. With repeated use it can cause paranoia, hallucinations, and psychosis, along with irritability, agitation, and deep depression as the drug wears off. Long term use is linked to persistent anxiety and mood disorders.
Cocaine constricts blood vessels and strains the heart, raising the risk of heart attack, stroke, and seizures even in young healthy people. Snorting damages the nose and sinuses; smoking crack harms the lungs.
Research and further reading
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Sabé et al. · Progress in Neuro-Psychopharmacology & Biological Psychiatry · 2021
Across all studies pooled, a large share of people who use cocaine had experienced psychosis symptoms like intense paranoia or hallucinations while using.
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Moçambique et al. · Brazilian Journal of Psychiatry · 2022
In this review of 2,252 cocaine users, about 44 percent had suicidal thoughts and about 28 percent had attempted suicide.
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Cardiovascular Risks of Simultaneous Use of Alcohol and Cocaine-A Systematic Review
van Amsterdam et al. · Journal of Clinical Medicine · 2024
Mixing cocaine with alcohol is even harder on the heart than cocaine alone, and the mix creates a byproduct called cocaethylene that greatly raises the risk of sudden cardiac death.
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Cocaine and Marijuana Use Among Young Adults With Myocardial Infarction
DeFilippis et al. · Journal of the American College of Cardiology · 2018
Among young adults who had a heart attack, those who used cocaine or marijuana had roughly double the risk of dying from heart problems compared to people who did not use.
Methamphetamine
Methamphetamine is one of the substances most strongly tied to psychosis. It can cause paranoia, delusions, and hallucinations that in some people last for months after stopping. The comedown brings crushing depression, exhaustion, and intense cravings, and long term use is linked to lasting problems with mood, memory, and decision making.
Physical harms include severe dental decay, skin sores, dangerous weight loss, heart damage, and higher risk of stroke and infectious disease.
Research and further reading
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McKetin et al. · EClinicalMedicine · 2019
A review of 149 studies found methamphetamine use linked to much higher odds of psychosis, violence, depression, and suicidal behavior.
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Cohen-Laroque et al. · Schizophrenia Research · 2024
Psychosis caused by methamphetamine can look just as severe as schizophrenia, with hallucinations and delusions that are just as intense.
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A systematic review of risk factors for methamphetamine-associated psychosis
Arunogiri et al. · Australian and New Zealand Journal of Psychiatry · 2018
The more often and more heavily someone uses methamphetamine, the more likely they are to develop psychotic symptoms.
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Curran et al. · Journal of the American Heart Association · 2022
In a study of over 20 million hospital patients, methamphetamine use raised the overall risk of heart and blood vessel disease by about 32 percent.
Opioids
This group includes heroin, fentanyl, and misused prescription pain pills like oxycodone and hydrocodone. Opioids hijack the brain's reward and pain systems. Over time they blunt the ability to feel pleasure from normal life, deepen depression, and increase suicide risk. Withdrawal brings intense physical sickness plus severe anxiety, insomnia, and agitation.
The greatest physical danger is overdose. Opioids slow breathing, and fentanyl is so potent that a tiny amount can be fatal. Injection use also raises the risk of HIV, hepatitis, and serious infections.
Research and further reading
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Prescription Opioid Duration, Dose, and Increased Risk of Depression in 3 Large Patient Populations
Scherrer et al. · Annals of Family Medicine · 2016
In three large patient groups, people who took prescription opioids for longer periods and at higher doses were more likely to develop depression.
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Initiation of Opioid Prescription and Risk of Suicidal Behavior Among Youth and Young Adults
Fine et al. · Pediatrics · 2022
In a nationwide study of nearly 2 million Swedish youth, those who started a prescription opioid had more than double the risk of suicidal behavior compared to young people who did not.
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Fleischauer et al. · MMWR · 2017
A CDC report tracking rising hospital stays for a life threatening heart valve infection linked to injection drug use.
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Increases in Drug and Opioid-Involved Overdose Deaths — United States, 2010–2015
Rudd et al. · MMWR · 2016
A CDC report documenting the sharp rise in US overdose deaths driven by opioids, showing overdose is one of the leading ways opioid use kills.
Nicotine (tobacco and vaping)
Many people smoke or vape to calm nerves, but nicotine actually worsens anxiety and depression between uses. Each dose wears off quickly, and the withdrawal that follows feels like anxiety, irritability, and low mood, which tricks the brain into thinking the nicotine helped. People with mental health conditions smoke at much higher rates and often find quitting improves their mood.
Smoking remains a leading cause of preventable death, driving heart disease, stroke, lung disease, and many cancers. Vaping avoids smoke but still delivers addictive nicotine and irritates the lungs.
Research and further reading
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Hu et al. · Frontiers in Medicine · 2025
Current smokers were more likely to develop major depression, schizophrenia, and bipolar disorder. As an observational study it cannot prove smoking caused them.
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Proposal for the Inclusion of Tobacco Use in Suicide Risk Scales: Results of a Meta-Analysis
Echeverria et al. · International Journal of Environmental Research and Public Health · 2021
Across about 2.5 million people followed over time, current smokers had a higher risk of dying by suicide and of having suicidal thoughts than people who did not smoke.
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Obisesan et al. · JAMA Network Open · 2019
People who vaped, especially daily, were more likely to report depression, although this one time snapshot cannot show whether vaping came first.
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Hackshaw et al. · BMJ · 2018
Even smoking just one cigarette a day carried a surprisingly large share of the heart disease and stroke risk of smoking 20 a day, so cutting back is not nearly as protective as quitting.
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Kim et al. · International Journal of Chronic Obstructive Pulmonary Disease · 2025
People who both vaped and smoked regular cigarettes were more likely to have COPD, a serious long term lung disease, and to report mental health problems than people who used neither.
Benzodiazepines and sedatives
Medications like alprazolam (Xanax), lorazepam (Ativan), clonazepam (Klonopin), diazepam (Valium), and prescription sleep aids calm anxiety quickly but are meant for short term use. With regular use the brain adapts, and anxiety often rebounds worse than before. They can impair memory and thinking, increase fall and accident risk, and deepen depression.
Stopping suddenly after regular use can cause dangerous withdrawal including seizures. Mixing these medications with alcohol or opioids greatly raises the risk of fatal overdose.
Research and further reading
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Hamadieh et al. · BMC Psychiatry · 2026
Combining 21 studies, people prescribed benzodiazepines were more than twice as likely to attempt or die by suicide. An association does not prove the medication caused it.
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Penninkilampi et al. · CNS Drugs · 2018
Across 15 studies with about 159,000 dementia cases, benzodiazepine use was linked to about a 39 percent higher chance of dementia, even after accounting for early dementia symptoms. This is observational and not proof of cause.
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Mortality associated with anxiolytic and hypnotic drugs-A systematic review and meta-analysis
Parsaik et al. · Australian and New Zealand Journal of Psychiatry · 2016
Pooling 25 studies of over 2.3 million patients, people using sleep or anti anxiety drugs had 43 percent higher mortality than non users, and benzodiazepine users specifically had 60 percent higher mortality.
Hallucinogens
LSD, psilocybin mushrooms, and PCP change perception and thinking. In vulnerable people they can trigger psychosis that persists long after the drug wears off. Some users develop frightening flashbacks or a lasting perceptual disorder, and bad experiences can leave lasting anxiety or trauma symptoms.
PCP in particular can cause dangerous agitation, high blood pressure, and violent behavior. All hallucinogens impair judgment during use, raising the risk of accidents and injuries.
Research and further reading
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Murrie et al. · Schizophrenia Bulletin · 2020
Among people who had already experienced hallucinogen induced psychosis, about 1 in 4 later received a schizophrenia diagnosis. The hallucinogen evidence was limited and strongly influenced by PCP cases.
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Pharmacological Treatment of Hallucinogen Persisting Perception Disorder (HPPD): A Systematic Review
Neven et al. · Harvard Review of Psychiatry · 2025
A review of 31 studies found hallucinogen use can leave some people with lingering visual disturbances and flashbacks that may last a year or more and seriously burden daily life.
MDMA (ecstasy, molly)
MDMA floods the brain with serotonin, creating warmth and closeness. As it wears off, the depleted serotonin system crashes, and the days after use often bring low mood, anxiety, irritability, and trouble sleeping. Heavy repeated use is linked to lasting depression, anxiety, and memory problems.
MDMA raises body temperature and heart rate. At parties or in hot settings it can cause dangerous overheating, dehydration, and in rare cases organ failure. Street pills sold as molly are often mixed with other drugs.
Research and further reading
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Ecstasy (MDMA) and memory function: a meta-analytic update
Laws et al. · Human Psychopharmacology · 2007
Across 26 studies, people who used ecstasy recreationally scored worse on short term and long term memory tests, especially verbal memory. Other drug use may have played a role.
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The pharmacology and toxicology of 'ecstasy' (MDMA) and related drugs
Kalant · CMAJ · 2001
This review identified over 87 ecstasy related deaths from dangerously high body temperature, muscle breakdown, heart rhythm problems, and liver failure, noting the toxic dose range overlaps the typical recreational dose.
Kratom
Kratom is sold in smoke shops and online as a natural remedy for pain, anxiety, or opioid withdrawal. But its active compounds act on opioid receptors in the brain. Regular use can cause dependence and a withdrawal syndrome much like opioids, with anxiety, insomnia, irritability, and low mood. Heavy use has been linked to psychosis and liver injury.
Because kratom products are unregulated, their strength varies widely and they are sometimes contaminated. Combining kratom with other sedatives raises overdose risk.
Research and further reading
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Kratom use and mental health: A systematic literature review and case example
Bachu et al. · Journal of Addictive Diseases · 2023
This review of published cases found kratom use linked to new or worsening psychotic and manic symptoms, especially in people who already had a psychiatric condition.
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Prevalence of Kratom Use Disorder Among Kratom Consumers
Smith et al. · Journal of Addiction Medicine · 2024
In a survey of 2,061 kratom users, about 1 in 4 met criteria for a kratom use disorder, most often marked by tolerance and withdrawal symptoms.
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Kratom Withdrawal: A Systematic Review with Case Series
Stanciu et al. · Journal of Psychoactive Drugs · 2019
Stopping regular kratom use can trigger withdrawal similar to opioid withdrawal, including depressed mood and anxiety.
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Kratom (Mitragyna Speciosa) Liver Injury: A Comprehensive Review
Schimmel et al. · Drugs · 2020
Kratom use can injure the liver, typically showing up as jaundice and abnormal liver tests within weeks of use, which usually improves after stopping but can occasionally become severe.
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Characteristics of deaths associated with kratom use
Corkery et al. · Journal of Psychopharmacology · 2019
Among 156 kratom associated deaths reviewed, most involved other substances too, and the toxic and fatal dose levels of kratom are still poorly understood.
Inhalants
Inhalants include solvents, spray paints, glues, aerosols, and nitrites. They produce a brief high by starving the brain of oxygen and disrupting nerve signals. Use can cause confusion, disorientation, and loss of coordination, and chronic use is linked to lasting problems with memory, thinking, and mood.
The most feared physical risk is sudden death. A single session can trigger fatal heart rhythm problems, even in a first time user. Long term use damages the brain, nerves, liver, and kidneys.
Research and further reading
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Garakani et al. · The American Journal on Addictions · 2016
Reviewing 91 published cases, heavy nitrous oxide misuse was linked to nerve damage, psychosis, and in some reports death, along with spinal cord injury in most cases.
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Boyce et al. · Epidemiologia · 2025
Among emergency department patients with recent nitrous oxide use, about half had psychotic symptoms and about a third had suicidal thoughts or self harm.
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Yücel et al. · Journal of Psychiatry and Neuroscience · 2010
Brain scans showed teenagers who used inhalants like toluene long term had more damage to the brain's wiring than cannabis users or people who did not use, which may explain lasting behavior and mental health problems.
Worried about your substance use?
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