Two recent fatal tragedies have cast the sale and use of marijuana edibles in the harshest of spotlights, and before you decide to indulge in these non-smokeable substances, it’s crucial to know what you’re getting into.

The first incident occurred a few weeks ago when a college student visiting Denver plunged to his death off a hotel balcony some time after eating a marijuana cookie. On Thursday, police announced that he had ingested six times the recommended amount of the edible. According to authorities, he first ate one-sixth of the cookie, as the retailer that sold it to him recommended. But when he wasn’t feeling its effects after awhile, he ate the rest of it. Within an undetermined number of hours he began acting erratically, and despite the efforts of his friends to calm him down, he bolted from his hotel room and fell to his death off a balcony overlooking the lobby.

A second marijuana-related fatality struck a Denver family on Monday when a local man allegedly shot and killed his wife while she pleaded with 911 operators to send help. She told the operators that her husband was “hallucinating” after having eaten a piece of marijuana candy about three hours earlier. Police are also investigating whether he had taken prescription painkillers the same evening.

I have a considerable amount of experience with marijuana edibles. I’ve been using them regularly for the past four years, and in the past six to 12 months I’ve eaten more pot than I’ve smoked. I’ve never experienced anything close to a psychotic episode, or even a hallucination. However, I also don’t have any history in my immediate family of psychosis or mental disorders such as bipoplar, schizophrenia, or panic attacks.

This is a crucial point. As I’ve written before, marijuana use alone cannot cause mental illness in people who are not already predisposed to it. (In fact, controlled doses of marijuana are sometimes used to treat conditions such as schizophrenia.) But if you are prone to such conditions, you should not use pot in any form without first consulting a physician—especially if you’re under 21.

Regardless, people should always approach edibles with extreme caution. In my experience, two pieces of the same candy can have entirely different effects in terms of the intensity and duration of a buzz, or how long it takes to set in. It depends on the time of day, what (regular food) you’ve eaten and when, how tired you are, or any number of other factors. If you’ve ingested the prescribed amount, you should probably wait at least two hours before concluding that “nothing’s happening” and trying more. And even then, “more” should be another nibble, not the rest of the piece.

Also, purchasing an edible should be roughly the same experience as filling a prescription at a drugstore. When you do that, the pharmacist asks if you have any questions about the drug and instructs you how best to take it. Most marijuana dispensaries and retailers responsibly perform the same ritual when selling edibles: Don’t eat more than this much, this is the kind of buzz you should expect, and so on. If your vendor is just handing you the bag and sending you on your way without making sure you understand what you’re buying, you need a new vendor.

These two recent tragedies are sure to spur discussions about the safety of edible marijuana, and our state legislature is already beginning to change some of the rules about how it’s produced and packaged. Rightfully so. Although these horrible incidents still have many unanswered questions, there should be no debate about the need to sell and consume these products with maximum care and responsibility.

Get Involved: A memorial fund has been set up in honor of Kristine A. Kirk, who was killed earlier this week, to help support her children. To learn more, visit this Facebook page.

Follow 5280 articles editor Luc Hatlestad on Twitter at @LucHatlestad.

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