The story of THC and CBD is one of modern love. As Russo summarized in his piece “A tale of two cannabinoids: The therapeutic rationale for combining tetrahydrocannabinol and cannabidiol” (see here) back in 2006, THC and CBD may just be better together. Like any good pair, THC and CBD seem to amplify each other’s good qualities and diminish the negative. There exists scientific evidence that suggests THC and CBD should be co-administered to improve the likelihood for therapeutic benefit. As we advance cannabis legalization, pharmaceutical approaches are inevitable and that territory likely comes with favoring isolates. However, we can learn a lot from the tale of the two major cannabinoids.
To begin this story, we must look to ECS engagement by the two major phytocannabinoids. (Refer to Introduction to the Endocannabinoid System for an educational primer on the ECS). THC engages our CB1 receptors effectively. Compared to CBD, it has a relatively easy time fitting into the main binding site of the CB1 receptors and initiating a variety of physiological signaling pathways. These include psychotropic activity (the high!) as well as pain and inflammatory relief. Now, CBD does not efficiently bind to the CB1 receptor nor the CB2 receptor. Isolated and alone, CBD cannot effectively engage our endocannabinoid receptors. However, when THC and CBD act together, CBD gains access to a secondary binding site on the CB1 receptor and is able to act as a modulator, specifically what we in the scientific community call an allosteric modulator,
When THC is bound to the main binding site of the CB1 receptor, a secondary binding site on that receptor opens up and CBD is able to bind. In this way, THC acts like the key to the CB1 receptor’s lock. Only when THC is already bound can CBD bind as well. When both THC and CBD are consumed in relatively low concentrations, this binding mechanism allows CBD to diminish the uncomfortable side effects of THC while amplifying the therapeutic benefit. And THC allows CBD to engage with the endocannabinoid receptors, thereby improving the likelihood for symptom relief. A match made in cannabinoid heaven.
What kinds of experiences does this binding mechanism manifest in patients? In the limited human clinical data we have to go on, it seems that CBD helps to attenuate the elevated heart rate, anxiety, memory impairment and sluggish side effects from THC. CBD and THC, when taken together, also improved the likelihood for pain relief and helped reduce muscle spasticity, especially in patients experiencing Multiple Sclerosis. Co-administered THC and CBD may also have neuroprotective effects and help to protect against neurotoxicity and Alzheimer’s disease.
Like any good partnership, THC and CBD seem to bring out the best in each other. If you are experimenting with cannabis medicine and not experiencing the relief you need from just THC or CBD, try them together! Especially in cases of neuropathic pain, CBD and THC seem to work better together. And you don’t need much! If you are trepidatious of THC, try just a little (1-2mg) in combination with your CBD. Even a 20:1 CBD:THC ratio could maximize the therapeutic action of your experience.