When THC enters your bloodstream, it rushes to every nook and cranny of your body — and in some spaces, it interacts with a natural system within you called the endogenous cannabinoid system (ECS). 

First discovered in 1990, the ECS seems to be a system integral to at least all mammals and possibly the group of animals that developed into mammals. The ECS in humans is incredibly complex, connected to a number of other systems within the body, to include the immune system, the reproductive system, the endocrine system, the digestive system, the nervous system and more.

As far as we can currently tell, the ECS is responsible for facilitating communication between these systems and for maintaining internal balance, called homeostasis. To accomplish these tasks, the ECS sometimes produces compounds, called endocannabinoids, which bind to different receptors to produce different effects.

The structure of THC is remarkably similar to one of these endocannabinoids, called anandamide. Anandamide is often called the “bliss molecule” because it helps the body and mind relax and enjoy pleasure.

Thus, THC successfully binds to ECS receptors around the body, inspiring similar effects to anandamide. Those effects are what make up the experience of being high: euphoria, muscle relaxation, hunger, increased libido, physical sensitivity and more. 

However, there tends to be much more THC in your body at one time than there ever is anandamide, which means THC binds in greater quantities to ECS receptors and produces much more intense effects. If you use more THC than your ECS is accustomed to, these effects are likely to be overwhelming, shifting from enjoyable to concerning. 

You might experience the symptoms of a THC overdose, which include panic, paranoia, nausea and hallucinations. These effects in and of themselves are not dangerous to your health, but they could put you in dangerous situations. 

For example, you are at greater risk for vehicle collisions or dangerous falls when you are especially high. Thus, you should understand your tolerance and increase your dosage slowly, and you should not drive or otherwise put yourself in dangerous situations when you use THC.