Editor's note: This article has been reviewed and updated for accuracy in 2026. Of the more than 100 cannabinoids in the cannabis plant, tetrahydrocannabinol (THC) is the one principally responsible for the psychoactive and intoxicating effects of cannabis consumption. Live cannabis plants contain tetrahydrocannabinolic acid (THCA), the non-active version of this compound. When cannabis is decarboxylated through heating to a high temperature, drying, or curing, the acid molecule (the “A” in THCA) drops off, and the THC is activated. This results in the effects we associate with consuming THC. It also means that cannabis in its fresh form is not yet active with THC. How does THC work? One of the first things researchers realized in their quest to understand how cannabis affects the body is that cannabis contains several active chemical compounds—over a hundred. As they studied cannabinoids, it became clear that these active compounds were interacting with receptors in the body. These receptors belong to the body’s complex nervous system, which uses neurotransmission to send and receive messages between the brain and the rest of the body. By interacting with these receptors, the cannabinoids were changing the brain’s normal communication. This left the researchers with an important question