Marijuana edibles — chocolates, gummies, and other culinary treats laced with tetrahydrocannabinol (THC) — are a relatively small part of the legal marijuana (cannabis) industry in Colorado.
Yet they’ve been putting a disproportionate number of people in the hospital.
According to a recently published in the journal Annals of Internal Medicine, Colorado saw a threefold increase in the number of people admitted to hospital emergency rooms that were attributable to cannabis between 2012 and 2016.
While a number of those cases were linked to inhaled cannabis, edibles played a significant role.
Cannabis edibles only comprise a small number of total cannabis sales, less than 1 percent based on THC content, and only 3.6 percent of marijuana users reported using edibles.
Despite their small market share, cannabis edibles resulted in nearly 11 percent of all cannabis-attributed emergency room visits.
Even more alarming, of the three deaths associated with cannabis products in Colorado, all involved edibles.
Andrew A. Monte, PhD, an associate professor of emergency medicine and medical toxicology at the University of Colorado in Denver, who authored the study, said he wasn’t surprised by the findings.
“This finally puts some data behind the observations that doctors have been seeing for years,” he told Healthline.
Dr. Ruben Baler, PhD, a health scientist administrator at the National Institute on Drug Abuse, who wrote an for the study, shares that sentiment.
“There have been inklings that different routes of administration would have different outcomes. There were preliminary results from emergency departments and poison centers already hinted at the differences. This clearly shows the differential risks of toxic adverse effects,” Baler said.
The study is the first to dive deep into adverse health outcomes from cannabis based on “route of exposure” — how the drug is consumed.
Cannabis is most commonly smoked, but it can be administered in other ways as well, including being eaten.
The drug’s effects on the body, it’s uptake (how long it takes to feel the effects), and duration are all affected by route of administration.
There were stark differences in emergency room patients’ symptoms based on whether they’d eaten or smoked cannabis. Edibles were more likely to induce acute psychiatric events, such as anxiety or panic attacks.
The most frequent reason for smoked cannabis to put users in the emergency room: cannabinoid hyperemesis syndrome, which results in repeated or cyclic vomiting that’s difficult to treat.
The study’s authors say that while smoked cannabis puts more people in emergency rooms in total, it’s clear that cannabis edibles are more likely to produce adverse health outcomes.
“There are more adverse drug events associated on a milligram per milligram basis of THC when it comes in form of edibles versus an inhaled cannabis,” Monte said. “If 1,000 people smoked pot and 1,000 people at the same dose in an edible, then more people would have more adverse drug events from edible cannabis.”
The question of why edibles have a disproportionately high number of these outcomes isn’t clear from the report.
It’s not uncommon to hear stories of users taking doses that are far too high or unintentionally taking too many doses at once.
“This may be because people who are impacted by the edible’s toxicity are naive users that haven’t had the experience before,” Baler said.
When eaten, cannabis takes a much longer time to kick in, and the high lasts longer. When marijuana is smoked, effects are noticeable almost immediately, with peak blood concentrations generally occurring within an hour. The high can last for a few hours.
Cannabis edibles can take an hour or more before any effects are noticed. The high lasts significantly longer — up to 12 hours. The delayed effects of cannabis edibles can lead to users eating more than they should.
Paul Armentano, the deputy director of the National Organization for the Reform of Marijuana Laws, told Healthline that eating THC products has a wider range of effects on people than smoking or vaping it.
He said the effects of the drug can also last longer and there’s a greater potential for a more dysphoric effect when it’s consumed in an edible form.
“This is because the body metabolizes THC in a fundamentally different manner following oral administration than it does following inhalation,” he said.
The study is the latest to scrutinize the harmful effects of cannabis edibles.
Last month, the Canadian Journal of Cardiology published a case report on a 70-year-old man who had a heart attack after ingesting a cannabis lollipop.
Cannabis affects the cardiovascular system and can cause an increase in heart rate and blood pressure. has noted an increased risk of heart attack following the use of cannabis.
Monte’s work is an important step toward understanding and acknowledging that cannabis consumed in different forms can lead to different yet serious adverse health outcomes.
What’s clear is that the public needs to be better informed about the effects and potency of edible cannabis.
“There needs to be greater awareness among both the consumer and the seller with regard to the fact that the route of administration plays a significant role in the duration and degree of drug effect,” Armentano said.
“The landscape has changed dramatically,” Baler said, noting that cannabis is much more potent today than it was in the past.
He also pointed out that with liberalization of marijuana laws there’s been a decreased perception of harm.
However, Baler says people shouldn’t panic.
“These emergency department visits should not be overstated. Our emergency department isn’t being overwhelmed with these visits. We see approximately 300 cases per day in our emergency department and really only one of those will be what we consider a ‘cannabis-attributable’ visit. So this is a really small percentage of the people we are seeing,” Baler told Healthline.
“Many people use cannabis safely without any adverse drug events,” he added.
While cannabis is used safely by many individuals, surveillance of adverse health outcomes is an important step for public health officials.
And individuals curious about cannabis edibles need to take care.
“Even low doses can cause adverse drug events,” Monte said.
“People need to be aware of this, put themselves in safe scenarios, and take lower doses when they first starting using cannabis edibles.”