head is spinning, and not from secondhand smoke.

"The normalization of weed is happening so fast it makes my head spin," the host of CNBC's "Mad Money" said on Friday. "It's not just that Canada and a host of states have outright legalized pot. It's that marijuana's gone mainstream."

Cramer's epiphany came when Brian Athaide, CEO of Canadian cannabis player Green Organic Dutchman, took the helm of the company after 25 years at Procter & Gamble, which Cramer called "the most mainstream company on Earth."

"I can't even explain how incongruous this is," he said. "A P&G executive in the marijuana business? A year or maybe two years ago, I would've told you that sounds about as plausible as 'Cheech & Chong join the DEA' or 'Harold & Kumar go to Breakfast at Tiffany's.'"

But with Canada approving full legalization of recreational marijuana use, a move set to go into effect in mid-October, Athaide calculated that "the opportunity was just too great," the "Mad Money" host said.

Still, risks remain when it comes to the investable portion of the marijuana market.

In his Tuesday interview with Brendan Kennedy, CEO of medical marijuana producer Tilray, Cramer warned investors about buying into the company's red-hot stock because of Tilray's lofty goals.

Tilray, a Canada-based cultivator that markets, develops and distributes marijuana products, aims to be "a global company" that "dominates part of [the] $150 billion industry" that medical cannabis could become, Kennedy said in the interview.

"I want to congratulate you on the success of your company," Cramer told the CEO. "I also want to caution people that you need more money, and whether it's a partnership or whether it's [an] equity offering, it certainly wouldn't be a bad idea. It's an expensive proposition to be as big of a consumer products company as you'd like to be."

On Tuesday, Tilray announced that it received approval from the Drug Enforcement Administration to ship cannabis to the United States for medical research. The shares surged nearly 29 percent on the news, tacking on another 70 percent in Wednesday's trading session.

Yet even with Canada's move, Athaide told Cramer at Friday's Green Market Report cannabis conference that investors shouldn't expect profits to surge when legalization goes into effect because there's so little infrastructure to sell cannabis products legally.

And while Cramer was fascinated by Athaide's market-share estimates — an up to $500 billion opportunity worldwide considering the potential for oil, pharmaceutical, pet health, edible and drinkable products — he agreed that Wall Street shouldn't get ahead of itself.

"I want to introduce you to these high-quality, new companies one by one, but I also need to echo Brian's concerns," he said. "Don't get ahead of yourself with the cannabis cohort or your gains could go up in smoke."

"So pay close attention, dabble if you want — my favorite remains Canopy because of Constellation's involvement — but don't believe all the hype," the "Mad Money" host concluded.