It's not a Myth: Marijuana really is More Potent than it used to be

This ain't your grandpa's weed. 

As cannabis becomes legal in more states in countries, it's a claim heard again and again: Today's marijuana is far more potent than it was in the '60s, supposedly. This week, Patrick Kennedy, a former Congressman from Rhode Island, repeated this assertion, tweeting, "The high concentration of THC in these marijuana products is not what people grew up with." THC is the main ingredient in cannabis responsible for the "stoned" or high feeling some people seek.

Though it might sound like one of many other drug scare tactics, there is some truth to the idea. Marijuana, the processed products of cannabis plants, is getting more potent over time. Thanks to specialized breeding techniques, cannabis can be cultivated to produce 30 percent THC or more — although there is a physical limit to how much the plant can actually spit out.

So how did this happen, and how has weed changed over the years? And does this really make it any more dangerous? 

The botany of really strong weed

Some of the stronger "weed" out there isn't actually weed, but concentrated versions of it — akin to how pure caffeine compares to coffee, or how cocaine is a concentrated version of the psychoactive drug in the coca leaf. To increase potency, cannabis chemists have, over the years, cooked up many different forms of concentrates. Recent concentrated cannabis innovations often involve industrial processing, and include butane hash oil, rosin, shatter, wax and budder. Some of these sticky confections can contain 90 percent THC or more. In June, The New York Times warned that teens are being poisoned by such products, triggering psychotic episodes and dependency.

Some health experts are extremely concerned about this trend, claiming it increases the risk of psychosis and addiction from ingesting cannabis. A recent review in The Lancet Psychiatry found that "higher potency cannabis is associated with poorer mental health outcomes." But the same researchers noted that these studies are prone to bias and have limitations, such as not measuring exposure levels.

Furthermore, studies on cannabis potency and mental health may not account for the fact that people more prone to psychosis may be more attracted to high potency THC products. It may not be that these highly potent products are causing these mental health problems and the authors note this, writing "participants with poorer mental health outcomes could use higher potency cannabis as a form of self-medication."

It's important to note that isn't exactly new. Potent cannabis products have existed for literally centuries. Concentrated cannabis resins known as hashish, which simply means "grass" in Arabic, were part of the 9th century pharmacopeia in ancient Persia, now called Iran. Its use inspired legends of assassins who would take hashish before slaughtering their enemies, but these accounts are not supported by historical evidence.

The market for super-potent weed

Today's issues stem from a lack of regulation and standardization across the industry, according to Peter Grinspoon, a primary care physician at Harvard Medical School who specializes in medical marijuana. Grinspoon is a board member of the advocacy group Doctors For Cannabis Regulation, which seeks to provide patients with evidence about the benefits and limitations of medical cannabis. He's also the son of Lester Grinspoon, the late associate professor of psychiatry at Harvard Medical School, who was an early proponent of medical marijuana.

"I had a front page seat at the legalization movement from day one," Grinspoon told Salon. Back then, he says, people were warned against using cannabis because smoking a whole joint was seen as bad for the lungs. Now just a single puff of a marijuana cigarette can be enough to send someone into a tailspin. "It's like cannabis can't win. Which is worse? To smoke a lot or just to smoke a little bit?" he muses.

Taking too much super-potent cannabis won't kill you, but you could have a pretty miserable experience, which could even require a trip to the ER. In fact, some point to an increase in poison control calls post-legalization, but these reports often neglect to note that these calls may be happening more frequently because the public is less afraid of legal consequences for consuming cannabis.

Nonetheless, weed is undeniably more dank these days, Grinspoon says. So what should be done about it, if anything? Some communities have demanded potency limits, with Florida recently enacting emergency rules restricting medical marijuana patients to no more than 24,500mg of THC per 70 days. Vermont and Connecticut are the only two other states that have imposed THC caps, with both banning concentrates above 60 percent.

"I think it is a little bit of experiment with these concentrates. But then again, you don't want to ban them, because then they just end up on the illicit market, and they're 1000 times more dangerous," Grinspoon says. After all, people seem to want high-THC marijuana, but unregulated products have been known to cause lung injuries. "So I just don't think criminalization is the answer, no matter what your thoughts are about the relative potency past, present or future."

But will these limits even work? Or will it just make marijuana more expensive, encouraging users to ingest twice as much? Grinspoon notes that many medical marijuana patients just want enough to alleviate their symptoms, nothing more. Not everyone wants to be super stoned.

"Many people really titrate to their own comfort. A lot of people don't like to smoke too much. They get anxious," Grinspoon explains. "I think the only thing [potency limits] really accomplishes is it makes it more expensive for people and drives people to the illicit market."

Getting used to it

One overlooked aspect to these limits is tolerance. Just because someone uses a more potent dose of THC does not mean they'll become more intoxicated. Regular use of cannabis causes the brain to downregulate or moderate itself, so users tend to get less stoned over time.

A 2020 study in JAMA Psychiatry gave either low or high THC concentrates to 121 Colorado adults who regularly consumed marijuana. While memory and/or balance was impacted in the short-term, the high THC group didn't experience more impairment than the low THC group. One reason for this, the authors suggested, is "cannabinoid receptors may become saturated with THC at higher levels, beyond which there is a diminishing effect of additional THC."

Of course, in less regular cannabis users, the high potency may still be a problem. This can be mitigated by starting low and going slow, Grinspoon advises.

"Start with a teeny bit. I say to my patients, if you're going to make a mistake of the dose, we're going to make a mistake by not taking enough. We're not going to make the mistake of taking too much and freaking out," Grinspoon says. "And people respond to that because nobody wants to be anxious. It's just not a good feeling to consume more cannabis than you want to consume."

Until cannabis is legalized federally, it will be difficult to standardize a typical dose of THC, Grinspoon argues. To make matters worse, many of the labels on cannabis can be misleading, as a study published last May found.

"There's no consumer protection," Grinspoon says. "If you over regulate, it just pops right into the illicit market and that's even more dangerous. So it's really a question of getting the regulation just right. And I don't think anybody's quite figured that out yet. It'd be a lot easier once we have federal legalization so things can be standardized."

Nearly 40 states have legalized medical marijuana, with adult use legal in 19 states, plus D.C., and a handful of U.S. colonies. Countries like Mexico and Germany may soon join Uruguay and Canada in legalizing adult-use cannabis. The question has largely shifted from should cannabis be legal to how best to regulate in a way that doesn't cause unforeseen harms.