So while CBD seems to mitigate the unfun effects of THC, it also might get in the way of certain medical benefits that THC has to offer. But because there’s seemingly no end to the complexities of cannabis, CBD might also enhance THC’s anti-cancer properties. Research has found that if you apply THC and CBD to cancer cells in the lab, the combination is more effective than THC alone at both inhibiting the growth of those cells and outright killing them. The future of medical cannabis, then, depends in large part on teasing apart the entourage effect—leveraging it in some cases, and maybe breaking up the entourage (or ensemble) when THC or CBD alone is most beneficial.

“We need to understand which constellations of plant chemistry are best suited for which indications and which kinds of patients, and which form of the CB1 receptor you happen to carry, because there are lots of mutations in that gene,” says Wilson-Poe. “So understanding these mechanisms is absolutely crucial for providing these patients with personalized medicine that alleviates their symptoms without producing the unwanted side effects.”

Hate to do this, but we’ve got one last problem. For decades, cannabis users have claimed that different strains of cannabis produce different effects—maybe it makes them sleepy, maybe it gives them energy. And that’s been true even as CBD was largely bred out of cannabis in North America in favor of THC. “Well, if they’re all high THC, it’s got to be from something else,” says Ethan Russo, director of research and development at the International Cannabis and Cannabinoids Institute, who studies the entourage effect. “And that something else is terpenoids.”