When people are smoking cannabis for the first time, or when they are hearing about its psychoactive effects, they’re pretty much hearing about THC, or tetrahydrocannabinol, one of the major cannabinoids in cannabis.
THC is the primary psychoactive part of cannabis, and it has an effect on cannabis users because it’s a bit of a trickster. Once it has been absorbed into the bloodstream, it makes its way to the brain and binds to cannabinoid receptors. These receptors use a neurotransmitter called anandamide, and THC emulates the same effects.
It can provide a very relaxing sensation, at some points stronger than others. When it comes to different strains of cannabis, the amounts of THC and CBD are important factors, as CBD, another cannabinoid, directly affects the effectiveness of THC by countering the effects.
When it comes to worrying about whether or not THC is still in your system, a big part of the answer is going to come down to your metabolism. Since everyone’s metabolism is a little different, everybody processes THC in a different way. On a general basis, though, if you have more fat on your body, it’s going to take longer for the stuff to get out of your system.
Looking at more specific numbers, you can start to get a general idea. A study in 1989 showed chronic users having a maximum detection window of about 25 days. Only one person in that test showed up as positive, and they took about another 10 days after the initial 14-day period to have the THC leave their system.
A second thing to consider is the quality of the drug test, should that be your concern. With a test at 50 ng/mL, one authority on the issue suggested 72 hour should be enough for an infrequent cannabis user to have the stuff leave their system. For more frequent users, it could be anywhere from seven to ten days.
As a side note, if you’re making use of other cannabinoids in cannabis beyond THC, you’re unlikely to run into issues with drug tests. Most drug tests are designed to exclusively detect THC, as it is the psychoactive substance in cannabis. People who use CBD or hemp oil are typically going to be fine, as hemp has too low of a THC level to matter and CBD is its own thing altogether.