Cheech and Chong may have wasted their ill-spent youth in their movie "Up in Smoke," but they didn't have a clue about the kind of edible marijuana treats that would flood the marketplace in their old age.

In the 1960s, there were only homemade hash brownies, thanks to "The Alice B. Toklas Cookbook" with its recipe for Hashish Fudge.

These days, there are marijuana-infused cookies, gummies, hard candies, pizza, chips, trail mix, ice cream, sodas, coffees, teas, energy drinks, and condiments.

As lighthearted as that all sounds, doctors writing in the Canadian Medical Association Journal are sounding an alarm, because most folks are not aware that ingested pot can take up to four hours to make its effects felt.

What happens? People eat and eat, trying to get a buzz, and end up overdosing. The effects can linger for up to eight hours, impairing driving, thinking, and walking for a long, long time.

Add to that the risk that pets or kids will gobble down the treats and end up poisoned by the toxic levels of THC they contain.

An adult serving of an edible might be one gummy bear (that equals one joint), or one square of chocolate. A kid or pet might eat a bunch or a whole bar and experience dizziness, paranoia, anxiety, hallucinations, difficulty breathing, and panic attacks.

If you're somewhere that edibles are legal (11 states allow recreational marijuana and 20 have okayed medical pot), be cautious when ingesting — or skip it altogether.

And always make sure to keep them away from kids and pets.