The marijuana available today is the same plant that has been used for thousands of years. Due to the large number of marijuana varieties, however, the level of THC – the main psychoactive ingredient – varies.

Illegal v. Legal Marijuana

Interestingly, marijuana tested in areas where it is illegal tends to be stronger. Why? Because when access to a particular substance is sporadic, risky and limited, both consumers and producers are incentivized to use or sell higher potency material.

There was a similar trend during alcohol Prohibition. Beer and cider were largely replaced by spirits and hard liquor, which was easier and more profitable to transport.

When access is regulated and controlled, as in states where medical marijuana is legal, we see a wider variety of potencies, including marijuana with virtually no traces of THC, but high in cannabidiol (CBD) – which is therapeutic, but not psychoactive.


Different methods of ingestion can also affect the strength of marijuana. Marijuana-infused edibles, for example, can have a stronger intoxicating effect and last longer than smoking. It’s important to regulate dosage and remember that it can take up to one hour before a marijuana edible takes effect.