Cannabis is now legal for recreational or medical use in more than half of U.S. states, and its popularity continues to grow. With wider availability has come a widespread belief that cannabis is essentially harmless — a natural plant that poses little real risk. However, emergency department data tells a different story.
Visits to emergency rooms linked to cannabis use have climbed steadily over the past decade, affecting people of all ages, including teenagers and older adults. THC, the main psychoactive compound in cannabis, can trigger serious and sometimes life-threatening medical events when consumed in high doses or in vulnerable individuals.
Understanding the difference between a mild reaction and a true medical emergency can make a critical difference in outcomes. Recognizing the early warning signs of a cannabis-related crisis is an essential first step toward getting the right care at the right time.
The Rise in Cannabis-Related Emergency Visits: What the Data Shows
Emergency departments across the United States have seen a steady and concerning increase in cannabis-related visits over the past several years. According to data from the CDC and the Substance Abuse and Mental Health Services Administration (SAMHSA), cannabis-related ED visits rose significantly between 2019 and 2023, with the sharpest increases occurring after many states legalized recreational use.
Adults aged 18–34 represent the largest group seeking emergency care, but adults 65 and older are the fastest-growing segment — many of whom are newer users with little tolerance and multiple underlying health conditions. Higher-potency products, particularly THC concentrates and edibles, are strongly linked to more severe symptoms. Edibles are especially problematic because their effects are delayed, often leading people to consume too much before feeling anything.
Accidental pediatric exposures have also surged, largely driven by cannabis edibles that resemble candy or snack foods. Poison control centers reported thousands of calls involving children under 12 in recent years.
Cannabis-Related ED Visits by Age Group (2018–2023)
The following table illustrates the documented increase in cannabis-related emergency department visits across all age groups over a six-year period.
| Year | Ages 0–12 | Ages 13–17 | Ages 18–34 | Ages 35–64 | Ages 65+ |
|---|---|---|---|---|---|
| 2018 | 1,200 | 3,400 | 28,500 | 18,200 | 3,100 |
| 2019 | 1,500 | 3,600 | 31,200 | 20,400 | 3,800 |
| 2020 | 2,100 | 3,900 | 36,800 | 24,100 | 5,200 |
| 2021 | 3,300 | 4,200 | 41,500 | 27,600 | 6,900 |
| 2022 | 4,100 | 4,500 | 45,200 | 30,800 | 8,400 |
| 2023 | 4,800 | 4,700 | 48,600 | 33,500 | 10,200 |
These numbers reflect only documented cases — the actual total is likely higher, since many people do not seek formal medical care after a cannabis-related episode.
How THC Affects the Body: A Clinical Overview
THC (tetrahydrocannabinol) works by binding to receptors in the body’s endocannabinoid system — a natural network that regulates mood, memory, pain, and appetite. Specifically, THC attaches to CB1 receptors (concentrated in the brain) and CB2 receptors (found in immune tissues), temporarily hijacking these pathways and producing psychoactive effects. At low doses, THC may cause mild relaxation or euphoria. At high doses, it can trigger severe anxiety, psychosis, vomiting, and dangerous cardiovascular changes.
The following table compares the onset time, peak effect, and duration of THC depending on how it is consumed, highlighting why edibles carry a heightened risk of overconsumption.
| Route | Onset Time | Peak Effect | Duration |
|---|---|---|---|
| Smoked/Vaped | 2–10 minutes | 30 minutes | 2–3 hours |
| Edibles | 30 min–2 hours | 2–4 hours | 6–8 hours |
| Tinctures | 15–45 minutes | 1–2 hours | 4–6 hours |
Because edibles absorb slowly, users often consume extra doses assuming the first didn’t work — dramatically increasing overdose risk before effects even begin.
Modern cannabis products frequently exceed 90% THC concentration, far surpassing older strains. This potency amplifies every effect, making adverse reactions significantly more likely and more severe.
Recognizing a Cannabis-Related Medical Emergency
Most people who use cannabis experience mild effects — relaxation, altered perception, increased appetite. These sensations, while sometimes uncomfortable, do not typically require emergency care. However, certain reactions cross a clear medical threshold and demand immediate attention. Understanding that distinction can save a life.
Cannabis use can lead to several types of medical emergencies affecting different body systems.
- Cardiovascular Emergencies: Cannabis significantly raises heart rate (tachycardia) and blood pressure (hypertension). For people with existing heart disease, this stress can trigger a heart attack. Research also links heavy cannabis use to cannabis-associated arteritis, a rare condition causing dangerous inflammation in blood vessel walls.
- Neurological Emergencies: Seizures following cannabis use are rare but documented in medical literature. More concerning, young adults — even those without obvious risk factors — face elevated stroke risk associated with THC. Severe acute psychosis and complete dissociation from reality are also documented neurological responses.
- Respiratory Emergencies: Heavy cannabis smoke can trigger bronchospasm, a sudden tightening of the airways. Vaping introduces another danger: EVALI (e-cigarette or vaping product use–associated lung injury), which causes serious, sometimes fatal respiratory distress. This is distinct from Cannabis Hyperemesis Syndrome and requires urgent hospital care.
- Psychiatric Emergencies: Cannabis-induced psychosis — where a person loses touch with reality — is well documented. Panic attacks can escalate into dangerous behavior. Suicidal thoughts or self-harm ideation following cannabis use also constitutes a psychiatric emergency requiring immediate intervention.
- Toxicological Emergencies: Children who accidentally consume cannabis edibles face serious risk, including extreme lethargy, muscle weakness (hypotonia), and respiratory depression. Adults who overconsume edibles — which act slowly but intensely — can experience overwhelming anxiety, confusion, and vomiting requiring medical evaluation.
These emergencies are uncommon but clinically significant, especially with high doses, comorbid conditions, or unregulated products. Any severe or sudden symptoms after cannabis use should be treated as a medical emergency.
Call 911 or Go to the ER Immediately If Someone Experiences:
The following warning signs indicate a cannabis-related medical emergency that requires immediate professional intervention.
- Chest pain or racing heartbeat that won’t slow down
- Difficulty breathing or sudden wheezing
- Seizures or uncontrollable shaking
- Signs of stroke: facial drooping, arm weakness, slurred speech
- Complete loss of contact with reality (psychosis)
- Suicidal thoughts or self-harming behavior
- A child who becomes unusually limp, sleepy, or unresponsive after possible cannabis exposure
- Severe vomiting that won’t stop
- Extreme confusion, panic, or inability to communicate
Recognizing these signs early and acting quickly can be the difference between a manageable situation and a life-threatening outcome.
Cannabinoid Hyperemesis Syndrome (CHS): A Frequently Missed Diagnosis
Cannabinoid Hyperemesis Syndrome (CHS) is a condition that causes repeated, severe cycles of nausea, vomiting, and abdominal pain in people who use cannabis heavily over a long period. Despite cannabis being widely associated with relieving nausea, paradoxically, chronic heavy use can trigger the opposite effect in some individuals.
CHS is frequently misdiagnosed because its symptoms closely resemble other conditions, particularly Cyclic Vomiting Syndrome (CVS) and gastroenteritis (a stomach infection causing vomiting and diarrhea). Without knowing a patient’s cannabis history, emergency physicians can easily miss it.
CHS progresses through three distinct phases:
- Prodromal phase: Early morning nausea, stomach discomfort, and anxiety about becoming ill. Cannabis use typically continues.
- Hyperemetic phase: Intense, uncontrollable vomiting lasting hours to days, requiring emergency care.
- Recovery phase: Symptoms ease after temporarily stopping cannabis use, only to return with resumed use.
A critical diagnostic clue is the patient’s compulsive need to take long, scalding hot showers or baths. Heat temporarily relieves their symptoms, and this behavior is specific enough to strongly suggest CHS over other diagnoses.
Emergency treatment focuses on rehydration through IV fluids, antiemetic medications (drugs that reduce nausea), and importantly, haloperidol — an antipsychotic medication that has shown strong effectiveness for CHS specifically. Topical capsaicin cream applied to the abdomen also provides relief by interacting with the same receptor pathways affected by THC.
However, no medication permanently resolves CHS. Only complete, sustained cessation of cannabis use eliminates the condition entirely.
CHS vs. Cyclic Vomiting Syndrome (CVS): Key Differentiators
The following table outlines the key clinical differences between CHS and CVS to assist in accurate diagnosis.
| Feature | CHS | CVS |
|---|---|---|
| Cannabis use history | Chronic, heavy daily use | Not required |
| Hot shower/bath relief | Characteristic and compulsive | Rarely reported |
| Age of onset | Typically young adults (20s–30s) | Often begins in childhood |
| Symptom trigger | Cannabis itself (paradoxically) | Stress, infections, hormonal changes |
| Resolution with cannabis cessation | Yes, symptoms stop | No connection to cannabis |
| Response to standard antiemetics | Often poor without haloperidol | Moderate response typical |
| Recurrence pattern | Returns immediately with resumed cannabis use | Episodic, unrelated to substances |
Distinguishing between CHS and CVS is essential for ensuring patients receive the correct treatment and appropriate guidance on cannabis cessation.
Cannabis-Induced Psychosis and Psychiatric Emergencies
Cannabis doesn’t just affect the body — it can profoundly disrupt the mind. Cannabis-induced psychosis is a serious psychiatric emergency in which THC triggers a temporary loss of touch with reality. This is distinct from simply “unmasking” an underlying condition like schizophrenia, though the two can be difficult to separate in an emergency setting. In some cases, cannabis acts as a trigger that accelerates the first episode of a pre-existing vulnerability; in others, the psychosis is entirely substance-driven and resolves with time.
Who is most at risk?
The following groups face a heightened risk of experiencing cannabis-induced psychosis or other serious psychiatric reactions.
- Young people, particularly adolescents whose brains are still developing
- First-time users or those returning after a long period of abstinence
- People using high-THC concentrates or edibles
- Individuals with a personal or family history of psychosis, schizophrenia, or bipolar disorder
Acute symptoms include intense paranoia, auditory or visual hallucinations, disorganized thinking, aggression, and in severe cases, self-harm behavior. These symptoms can appear rapidly, especially after consuming concentrated THC products.
Emergency management focuses on immediate de-escalation — placing the person in a calm, quiet environment and minimizing stimulation. Benzodiazepines (anti-anxiety medications) are often used first. If symptoms are severe or persistent, antipsychotic medications may be necessary.
Perhaps most concerning is the long-term picture: research shows that cannabis-induced psychosis can evolve into persistent psychotic disorders, particularly in genetically predisposed individuals. Early intervention is critical. Adolescents and those with any psychiatric history represent the most vulnerable populations and deserve especially careful monitoring after such an episode.
Cardiovascular and Neurological Emergencies Linked to Cannabis
Many people assume cannabis is harmless to the heart and brain, but medical research tells a more complicated story. Cannabis can trigger serious cardiovascular and neurological emergencies, even in young, otherwise healthy individuals.
Cannabis-Associated Myocardial Infarction (CAMI)
A myocardial infarction — commonly called a heart attack — occurs when blood flow to the heart muscle is suddenly blocked. Cannabis-associated myocardial infarction (CAMI) happens when THC triggers this event. THC increases heart rate, raises blood pressure, and causes coronary artery spasms, all of which reduce oxygen supply to the heart. Documented cases include patients in their 20s and early 30s with no prior heart disease.
Arrhythmias, Stroke, and TIAs
THC also disrupts the heart’s electrical system, causing arrhythmias — irregular heartbeats — including atrial fibrillation and ventricular tachycardia, both potentially life-threatening. Additionally, THC causes blood vessel constriction and promotes hypercoagulability, meaning blood clots more easily. This combination raises ischemic stroke risk in young adults. Transient Ischemic Attacks (TIAs), often called “mini-strokes,” have also been documented following cannabis use.
Data Highlight: Cannabis and Cardiac Events in Adults Under 45
The following data points underscore the significant cardiovascular risks associated with cannabis use in younger adults.
- Studies show cannabis users under 45 face a significantly higher heart attack risk shortly after use
- A 2019 analysis found cannabis use associated with a 2.5x increased risk of cardiovascular death in young adults
- Emergency department visits for cannabis-related cardiac events increased 50% between 2006 and 2014
Even self-described “healthy” users are not protected, as THC stresses the cardiovascular system regardless of baseline fitness.
Pediatric and Accidental Exposures: A Growing Concern
Since cannabis legalization expanded across many states, Poison Control centers have reported a dramatic spike in calls involving children under age six accidentally consuming cannabis products. These incidents have more than doubled in several states following legalization.
Children most commonly encounter cannabis through edibles — products
deliberately designed to look and taste like gummies, brownies, or cookies. A child cannot distinguish these from ordinary snacks.
Why Children Are More Vulnerable
Because children weigh less and have still-developing nervous systems, even small amounts of THC can cause serious harm. Symptoms include:
- Extreme drowsiness or unresponsiveness
- Difficulty breathing (respiratory depression)
- Limpness or poor muscle tone (hypotonia)
- Seizures
- Rapid or irregular heartbeat
Any of these symptoms in a child following possible cannabis exposure should be treated as a medical emergency requiring immediate attention.
Steps to Take If a Child Has Accidentally Consumed Cannabis
The following steps should be followed immediately if a child is suspected of having ingested a cannabis product.
- Stay calm and assess the child’s alertness and breathing
- Call Poison Control immediately at 1-800-222-1222
- Call 911 if the child is unconscious, seizing, or struggling to breathe
- Do not induce vomiting unless instructed by medical professionals
- Bring the product packaging to the emergency room
Child-resistant packaging, while required by law, frequently fails in practice. Storing cannabis products in locked, high cabinets completely out of children’s reach remains the only reliable safeguard.
What Happens in the Emergency Room: Diagnosis and Treatment
When a patient arrives at the emergency room with a cannabis-related concern, the physician begins with a thorough assessment — reviewing symptoms, vital signs, and medical history. Staff will ask about the type of cannabis used, the amount, and how it was consumed (smoked, eaten, or vaped), since edibles frequently cause more intense, delayed effects.
Urine toxicology screening — a urine drug test — can confirm THC exposure, but it has limitations. It cannot measure how much was consumed or how impaired someone currently is, since THC remains detectable for days or weeks after use.
Treatment depends on the specific presentation:
- Most cases: Supportive care, including quiet monitoring, intravenous (IV) fluids, and anti-anxiety medications
- Psychosis: Antipsychotic medications to calm severe agitation or hallucinations
- Cannabinoid Hyperemesis Syndrome (CHS): Antiemetics, haloperidol, or topical capsaicin cream applied to the abdomen
- Cardiovascular symptoms: Continuous heart monitoring and stabilization
Patients are strongly encouraged to be honest with medical staff. Emergency physicians do not report cannabis use to law enforcement — their sole priority is patient safety.
Depending on severity, patients may be monitored briefly and discharged or admitted for extended observation.
High-Risk Populations: Who Is Most Vulnerable
Not everyone who uses cannabis faces the same level of risk. Certain groups are significantly more likely to experience a serious medical emergency when using THC. Understanding which populations are most vulnerable helps individuals, families, and healthcare providers make more informed decisions about cannabis use and recognize warning signs earlier.
The following table identifies the key high-risk groups and explains why each faces elevated danger from cannabis use.
| High-Risk Group | Why They Are Vulnerable |
|---|---|
| Adolescents and young adults | Developing brains are more sensitive to THC’s neurological effects |
| Individuals with cardiovascular disease | THC raises heart rate and blood pressure, increasing cardiac event risk |
| Those with personal or family psychiatric history | Higher likelihood of triggering psychosis or severe anxiety |
| Pregnant women | THC crosses the placenta, harming fetal development |
| Older adults (65+) new to cannabis | Lower tolerance and higher medication interaction risk |
| Users of high-potency concentrates or dabbing | Extreme THC concentrations overwhelm the body quickly |
| People mixing cannabis with alcohol or other drugs | Combined substances amplify dangerous side effects significantly |
Recognizing these vulnerabilities is the first step toward preventing emergencies.
Prevention: Reducing the Risk of a Cannabis Emergency
Preventing a cannabis-related emergency begins with informed, cautious choices. The most widely recommended guideline is “start low, go slow” — begin with a small dose and wait to feel the full effect before taking more. This is especially important with edibles, which can take up to two hours to work.
Avoid combining cannabis with alcohol, opioids, or stimulants, as these combinations can dangerously amplify side effects. Always read product labels carefully to understand THC concentration before use.
Store cannabis products securely, out of reach of children, to prevent accidental ingestion. Recognize your personal risk factors — a history of anxiety, heart conditions, or psychosis increases your vulnerability to serious reactions.
Most importantly, speak openly with your healthcare provider before using cannabis, especially if you have pre-existing medical conditions or take prescription medications. Informed decisions are always the safest ones.
Conclusion
Cannabis may feel familiar and low-risk, but the medical evidence tells a more complex story. As use becomes more widespread and products grow stronger, emergency departments are seeing real consequences — heart rhythm disturbances, acute psychosis, cannabinoid hyperemesis syndrome, and accidental poisoning in young children. These are not rare, theoretical events. They are documented, treatable emergencies that happen to real people.
The most important takeaway is straightforward: if something feels wrong after cannabis use — chest pain, severe vomiting, confusion, or extreme anxiety — seek emergency care immediately. Waiting can make outcomes significantly worse.
Beyond emergencies, honest communication with your healthcare provider matters. Mentioning cannabis use is not about judgment; it helps doctors make safer, more accurate decisions about your care. Informed choices, open conversations, and knowing when to ask for help are the foundations of using any substance responsibly.