CBD Could Be a Powerful New Antibiotic, Scientists Say

Even microbes could soon be micro-dosing cannabis compounds, according to a new study. 

Cannabidiol (CBD), cannabis’ famously calming compound, has a swathe of antibiotic properties in mouse models that makes it a worthy candidate for future antibacterial treatments, researchers say. 

As antibiotic resistance becomes a growing health risk around the world – with some experts warning that everyday infections could again become life-threatening – any new antibiotic candidates are highly prized. 

Now, new research has claimed that CBD is active against several bacterial species that can cause serious infections, such as Staphylococcus aureus. The study’s authors, who debuted their research today at the American Society for Microbiology’s annual meeting, say that CBD’s antibiotic potency is on par with established antibiotics like vancomycin.

However, they can’t yet explain how the famous cannabinoid is achieving its bacteria-killing effect. 

“We don't know [its actions] yet, so that's one thing that we're very interested in investigating further,” said Dr Mark Blaskovich, who led the research at the University of Queensland in collaboration with the drug discovery company Botanix Pharmaceuticals Ltd. 

“One of the most obvious ways [CBD could act] would be to damage the membrane of the bacteria. But the assay that we've done shows that's not the primary mechanism of action.”

“Even for antibiotics that have been around for a long time, like polymyxins which were discovered in the 1940s, we still don't know, completely, their mechanisms of action,” he explained. 

“So if you know it's effective at killing the bacteria, and it’s not inducing resistance – which appears to be the case for CBD – there shouldn't be any significant roadblocks in advancing it further, from a regulatory perspective.”

Antibiotic resistance can occur when a random mutation arises in a bacterium’s genetic code that confers some kind of resistance against antibiotics. The bacterium can then survive antibiotic exposure and pass on its mutation to other bacteria, spreading the resistance. 

The team behind the new study say that when exposed to such highly resistant bacteria, CBD retained its killer activity. And even when the microbes were put under extended exposure conditions that could lead to resistance against common antibiotics, the cannabis compound didn’t lose its effectiveness. 

“It’s a substantial advantage over most other existing antibiotics,” said Blaskovich. “At some point, we’ll find that resistance does occur, because for every antibiotic ever introduced, resistance has happened.” 

“But if you put [CBD] under similar conditions to known antibiotics, such as vancomycin, those antibiotics will induce a 20-fold increase in the minimum inhibitory concentration required to stop the growth of the bacteria. Under the same time frame, there's, at most, a four-fold increase for cannabidiol… which suggests that its mode of action is quite unique from most other antibiotics.”

Despite the cannabis compound’s great antibiotic potential, Blaskovich is keen to dissuade anyone from swapping their clinically proven antibiotics for a vial of CBD oil. According to the chemist, the compound is completely ineffective as an antibiotic if not properly prepared.  

“I certainly wouldn't advise consumers to go out and be taking a lot of cannabidiol on their own to try treating infections - certainly for systemic infections; drinking or inhaling cannabidiol has not been shown to be effective at all.” 

Further research will be required to test CBD’s antibiotic properties to the levels expected of a clinically approved drug. And Blaskovich himself is eager to further probe the cannabinoid’s potential, especially given the limitations his study hinted at. 

“So far, we haven't been able to show that it actually has efficacy in the models where you need a systemic delivery of the drug,” he clarified. “But it does work topically.”

Given the gravity of the antibiotic resistance crisis, any candidate that shows such promise will likely receive significant follow-up research and investment. But certain researchers have urged caution over the hype that can surround such novel antibiotic sources.  

“Finding antimicrobial substances from any natural environment is helpful in the search for new antibiotics – particularly if they are active against the WHO priority pathogens,” Laura Piddock, a professor of microbiology at the University of Birmingham, told the Guardian last month. 

“However, going from the test tube to a safe and efficacious drug in a patient is only the beginning of a lengthy and costly drug development process.”