A cannabinoid is any chemical compound that interacts with a specific network of receptors found throughout your body, known as the endocannabinoid system. These compounds fall into three categories: those your body makes naturally, those produced by the cannabis plant, and those created in a laboratory. Over 150 unique cannabinoids have been identified in cannabis alone, and they vary widely in their effects, from psychoactive to therapeutic to entirely inert.
The Three Types of Cannabinoids
Plant-derived cannabinoids, called phytocannabinoids, are the most familiar. THC and CBD are the two most abundant, but they share the plant with more than 150 other cannabinoids, each with a slightly different chemical structure and set of effects. Lesser-known ones like CBG and CBN are getting more research attention for potential anti-inflammatory and anticancer properties, though clinical evidence in humans is still early.
Your body also produces its own cannabinoids. The two primary ones are anandamide and 2-AG. These molecules are made on demand, do their job at nearby cells, and are quickly broken down by dedicated enzymes. They play a role in regulating how nerve cells communicate, particularly by dialing down signals at synapses that use the brain’s main excitatory and inhibitory chemical messengers. This makes them important players in processes like memory formation and stress response.
Synthetic cannabinoids are engineered in labs to mimic or modify the effects of natural cannabinoids. Some are used in approved medications. Others, like those found in illicit products sometimes called “spice” or “K2,” can be far more potent and dangerous than anything found in a plant because they fully activate receptors that THC only partially triggers.
How the Endocannabinoid System Works
Cannabinoids do their work by attaching to two main receptor types, called CB1 and CB2. CB1 receptors are concentrated in the brain at very high levels in certain regions, with lower levels spread more broadly. These are the receptors responsible for the psychoactive effects of cannabis. CB2 receptors have a much more limited distribution, found primarily on immune cells and a small number of neurons.
When a cannabinoid reaches a receptor, what happens depends on how it fits. A compound that activates the receptor is called an agonist. One that blocks the receptor without activating it is an antagonist. THC is a partial agonist at CB1, meaning it activates the receptor but not to its full capacity. This is part of why THC produces a high but has a ceiling to its effects. CBD, by contrast, has very low affinity for CB1 and CB2 and instead influences the system more indirectly, which is why it doesn’t produce intoxication.
The strength and nature of a cannabinoid’s effect comes down to how deeply its molecular “tail” fits into specific pockets within the receptor. A longer tail pushes key structural elements farther apart, opening the receptor more fully. A shorter tail may sit in the pocket without triggering the switch at all. This is why closely related molecules, like THC and its shorter-tailed cousin THCV, can have opposite effects: THC partially activates CB1, while THCV acts as an antagonist.
How Cannabis Makes Cannabinoids
All cannabinoids in the cannabis plant trace back to a single precursor molecule called CBGA, sometimes referred to as the “mother cannabinoid.” The plant builds CBGA from simple fatty acid building blocks, then different enzymes convert it into the precursors of THC, CBD, CBC, and other cannabinoids. Heat (from smoking, vaping, or cooking) then converts these acidic precursors into their active forms. This is why raw cannabis doesn’t produce a high, as the THC hasn’t yet been activated from its acid form, THCA.
FDA-Approved Cannabinoid Medications
The U.S. Food and Drug Administration has approved four cannabinoid-based drugs. Epidiolex contains a purified form of CBD and is used to treat seizures in patients one year and older with Lennox-Gastaut syndrome, Dravet syndrome, or tuberous sclerosis complex. Two other medications, Marinol and Syndros, contain a synthetic version of THC approved for treating appetite loss and weight loss in AIDS patients. A fourth, Cesamet, contains a synthetic compound structurally similar to THC.
These approvals are notable because they represent the small fraction of cannabinoid research that has cleared the highest bar of clinical evidence. Many other cannabinoids show promise in lab and animal studies, but the gap between petri dish results and proven treatments in people remains large for most of them.
Side Effects and Safety
In clinical trials of medical cannabinoids, side effects are common but mostly mild. In a systematic review covering thousands of reported adverse events, 96.6% were classified as not serious. Dizziness was the most frequent complaint, accounting for about 15% of all non-serious events. Nervous system effects as a category (including dizziness, drowsiness, and difficulty concentrating) made up the largest share at roughly 37%.
The rate of non-serious side effects was nearly twice as high in people taking cannabinoids compared to those taking a placebo. Serious adverse events, however, occurred at essentially the same rate in both groups. The most commonly reported serious events included gastrointestinal problems like vomiting and respiratory issues.
One significant gap in the evidence is long-term safety. Most clinical trials of cannabinoids have been short, with a median exposure of just two weeks and the longest lasting 12 months. The risks associated with years of regular use are not well characterized in controlled research, which means much of what we know about long-term effects comes from observational data with all its limitations.
CBG, CBN, and Other Minor Cannabinoids
Beyond THC and CBD, researchers are increasingly studying the “minor” cannabinoids that appear in smaller quantities in the plant. CBG (cannabigerol) is of particular interest because it interacts with the body differently than THC or CBD. It has low affinity for the main cannabinoid receptors but strongly blocks a temperature-sensing receptor called TRPM8, which has been linked to cancer cell growth in some lab studies. CBG has shown the ability to inhibit colon cancer cell growth in preclinical research, and both CBG and CBN (cannabinol) have demonstrated the ability to trigger cell death in leukemia cells in laboratory experiments.
These findings are promising but preliminary. Lab studies on isolated cells don’t account for the complexity of a living human body, and effective concentrations in a petri dish don’t always translate to achievable or safe doses in people. Still, the diversity of cannabinoid compounds and the range of receptors they interact with suggest that the therapeutic potential of this class of molecules extends well beyond THC and CBD alone.