Among teens ages 16 to 18 who needed emergency or hospital care because of a substance-related problem, 84% had at least one encounter involving cannabis, according to a study published Nov. 4 in The American Journal of Psychiatry. Alcohol was involved for 33% of that age group. The study, led by researchers at WashU Medicine in St. Louis, analyzed more than 5 million substance-related emergency visits and hospitalizations among 1.3 million people ages 16 to 64 from 2016 to 2023. The pattern flipped with age. Among adults 55 to 64, cannabis was involved for 19%, and alcohol for 70%.
The 84% figure needs careful reading, because it is not a measure of what sent teens to the hospital. Involved means cannabis appeared anywhere in the patient’s diagnosis list, not that it caused the visit.
Age Patterns Across 5 Million Encounters
The fastest growth came among young adults. The share of encounters involving cannabis rose about 1.8 percentage points a year among people ages 19 to 24, the steepest increase of any group, and about 0.8 points a year among teens. Older groups changed little.
The researchers also found increases in cannabis-related hospital admissions involving psychosis and severe vomiting among younger people, according to the study’s news release. The release did not give numbers for those trends.
Alcohol remained the leading problem for older adults. The steepest alcohol trend was in hospitalizations where alcohol was the primary reason, rising about 3.6 percentage points a year among people ages 25 to 34.
Senior author Dr. Kevin Y. Xu, an assistant professor of psychiatry at WashU Medicine, said that until now researchers “haven’t had high-quality data tracking what kind of use is causing immediate harm.”
Involvement Is Not Cause
The study’s definition of cannabis involvement is broad. A teen treated after a car crash, a fall or a psychiatric crisis would count if cannabis use appeared on any diagnosis in the record, even if it played no role in the reason for the visit.
Nearly half of cannabis-related encounters also involved at least one other substance, according to News-Medical. When the researchers looked only at hospital admissions where cannabis was the primary reason, the trend among adolescents declined. That suggests cannabis may often be one factor among others, including other drugs and mental health conditions.
The data came from insurance claims, including commercial plans and Medicaid, so people without insurance were not captured, and diagnosis codes depend on what clinicians record. The study is observational, so it shows patterns and trends rather than cause and effect.
The research was funded by the National Institutes of Health and several Washington University programs, and the study was peer-reviewed.
Signs Parents Should Not Ignore
Today’s cannabis products are often far stronger than in past decades, which can make it easier to take too much, especially with edibles that take longer to kick in. The WashU release cited separate research suggesting cannabis use disorder becomes more likely above roughly 30 milligrams of THC a week for adolescents and 40 milligrams for adults. The risk of developing cannabis use disorder is higher in people who start using cannabis young and in those who use it often, according to the CDC. Cannabis affects brain areas involved in memory, learning, attention, and decision-making.
Two problems flagged in the study deserve attention. Psychosis can involve seeing or hearing things that are not there, extreme paranoia, or confused thinking. Cannabis hyperemesis syndrome causes repeated, severe vomiting and stomach pain in some frequent users, who often find temporary relief in hot showers. Both need medical evaluation.
Teens and young adults with a family history of psychosis, those using high-potency products daily, and those combining cannabis with alcohol or other drugs may face the highest risk. Young children face a separate danger from edibles left within reach. “Children who consume THC-containing products can become very sick,” the CDC warns.
Call 911 or go to an emergency department for chest pain, trouble breathing, severe confusion, seizures, thoughts of self-harm, or vomiting that will not stop. For a young child who may have eaten an edible, call Poison Control at 1-800-222-1222 or seek emergency care.
Starting the Conversation at Home
Parents can ask open questions about what products friends use and how they are bought, rather than starting with punishment. Teens who feel judged are less likely to call for help when a friend is in trouble. Storing any cannabis products locked and out of sight protects younger siblings and visitors.
Families looking for help can ask a pediatrician or primary care clinician about screening and treatment for substance use. SAMHSA’s National Helpline, 1-800-662-4357, offers free, confidential referrals around the clock, and the 988 Suicide and Crisis Lifeline answers calls and texts at any hour.
The researchers said more work is needed to explain why harms vary across age groups. MedicalDaily will report on new research on cannabis potency and youth emergency care.
