In a commentary in the medical journal CMAJ, researchers explored the possible dangers associated with foods containing cannabis.
Risks include inadvertent overdose, because it takes much longer for edible cannabis to take effect, accidental consumption by children and unexpected potency in the elderly.
“What we really want the public to know is that legal doesn’t mean safe,” said study coauthor Dr. Lawrence Loh, an adjunct professor at the Dalla Lana School of Public Health at the University of Toronto. “People need to know that how they react will depend on the manner cannabis is consumed, the amount that is consumed and the person’s own metabolism and biokinetics. That’s why we advise they be cautious when using edibles.”
One issue, Loh said, is that it can take hours for the cannabis high to hit if the drug is taken in an edible form rather than inhaled. So there might be a temptation to take more in the meantime, which could lead to an overdose.
While a cannabis overdose won’t kill you, it can be unpleasant, Loh said. “Basically people can experience a racing heart, sweatiness, delusions and hallucinations,” he added.
“We suggest people start with a low dose and go slow,” Loh said.
Loh and his coauthor also recommend seniors be extra careful with edible cannabis because older adults, especially those who are not familiar with the drug, could be at greater risk for falls and injury.
Another warning: adults should be aware that edible cannabis products may appeal to children who don’t know what they are. So these products should be stored away carefully “to make sure kids can’t get into it,” Loh said.
The authors also suggest that physicians add questions about cannabis to those they routinely ask a patient so they can offer education and advice.
An alert such as this one, “is really important,” said Dr. Michael Lynch, medical director of the Pittsburgh Poison Center and assistant professor in the division of medical toxicology at the University of Pittsburgh School of Medicine in Pennsylvania.
The delayed onset of THC effects can throw some people off, Lynch said. “The delay can be a benefit for some if they are not looking for a rapid, significant high, but instead are looking for a more drawn out and deliberate experience. But people need to understand that they should avoid taking more because the effect is delayed.”
And while the risk of dying from an overdose is low, Lynch said, “the potential risk for medical complications or injury is very real. The greatest risk is to the young and the old.”
Those who overdose would be at risk for “intoxication, impairment, inability to coordinate movement, falls, nausea and vomiting,” Lynch said. “For some there would be a risk for psychotic types of events.”
A speeded-up heart rate and a spike in blood pressure could also be more of a problem for older people, Lynch said.
Another issue with edibles, due to the fact that onset is slow and drawn out, is that people could still be impaired when they show up at work in the morning, Lynch said.
“People need to be educated about the risk so these outcomes can be avoided,” Lynch said.