Recent news about CBD’s interactions with pharmaceutical drugs has been making waves inside and outside the cannabis sphere, causing naysayers to wag their fingers about the potential dangers of this, or other cannabinoids. Juxtaposed against the CBD craze, with many advocates painting the compound as a panacea for everything from PMS to epilepsy, consumers or the canna-curious are left wondering about how to separate helpful cautions from fear-mongering.
Let’s tease out the specifics of this issue.
What’s CBD Good For?
CBD, or cannabidiol, is a highly therapeutic, non-psychoactive compound found in cannabis. It’s been studied as a successful anti-epileptic, while a CBD-based pharmaceutical called Epidiolex is gaining market share for kids with intractable epilepsy. In a related pathway, CBD is known to calm the nervous system for those suffering from muscle spasms associated with Parkinson’s and ALS, and is generally known as a muscle relaxant.
For more everyday symptoms like anxiety, insomnia, and inflammation, CBD is being used regularly by seven percent of Americans to tame stress, get a better night’s sleep, and help the body heal itself. As a topical ointment, it helps with sore muscles, headaches, and run-of-the-mill pain.
CBD is sold in numerous forms, including oils, tinctures, capsules, gummies, and even flower. Derived from hemp or marijuana (the former having less than .3 percent THC), CBD ss also infused into various foods and drinks available everywhere from dispensaries to coffee shops.
With the 2018 Farm Bill having effectively legalized CBD nationwide, along with its ever-increasing availability and market share, it’s no wonder that more and more people are learning about, buying, and consuming CBD. And with this flurry of new ways people are using CBD, come new concerns—and a need for more robust research.
What Are the Potential Side Effects of CBD Alone?
Depending on the dosage, and the variations between each person’s endocannabinoid system (ECS), CBD is sometimes associated with tiredness, diarrhea, and appetite changes. Not everyone tolerates CBD well, but those who do often report dramatic improvements in the quality of their physical and mental health.
What are the Potential Interactions with Pharmaceutical Drugs?
More than half of American adults take at least one prescription drug, and many of them — particularly seniors — are prescribed a cocktail of daily meds. We know that pharmaceuticals can interact with one another, as well as with other substances.
Take grapefruit, for instance: a healthy and seemingly harmless food that nonetheless affects a group of liver enzymes in the human body, and thereby alters the way drugs are metabolized. Consuming grapefruit or grapefruit juice can augment the effects, or prolong the presence of, certain drugs in the body — which means that the drugs either may not work as intended or may present more severe side effects. That’s why a significant number of prescription meds carry a warning against consuming grapefruit.
Broadly speaking, CBD is thought to work in the same way. The liver enzymes concerned are in a group called Cytochrome P450 which are known to process drugs and toxins, including those found in about 60 percent of pharmaceutical meds. Because, in simple terms, CBD “occupies” those enzymes for a period of time, the cannabinoid taken alongside prescription meds can interfere with the drugs’ effects.
“Unfortunately, the very busy enzymes are the ones that deal with CBD (but not THC), so adding CBD can overload the capacity of those enzymes," Dr. Jordan Tishler, a medical marijuana doctor in Massachusetts, wrote in an email to Civilized. "Oddly this can cause increases or decreases in the medication levels. It’s somewhat unpredictable.”
However, according to Rosalia Yoon, PhD., research scientist at Apollo Cannabis Clinics, most of the information about CBD and drug interactions comes from molecular and animal studies. Others cite case studies to show that CBD has interfered with certain drugs’ actions, but clinical research is somewhat sparse, owing to a few factors: Primarily, federal prohibition has historically made it hard for researchers to get projects approved and funded, and secondly, people metabolize cannabinoids, including CBD, differently — so one person’s adverse dose may be another’s optimal dose.
Which Drugs Are Affected?
According to Dr. Tishler, there are a number of medications that CBD could affect, including benzodiazepines, blood thinners, cardiac medications, seizure drugs, and immunosuppressants used in the case of organ transplants. “Many of these medications need very specific levels," he said, in order to work safely and well.
CBD can augment and prolong the effects of warfarin, prescribed as a blood thinner, as well as those of ibuprofen. The risks of over-bleeding grow with the simultaneous use of CBD and these drugs.
Because CBD and THC both carry sedative properties on their own, combining them with sedating benzodiazepines like Xanax, Klonopin, Valium, and Atavan could boost the effects of those drugs in a potentially dangerous way.
CBD is known as an antiepileptic in its own right. However, it must be closely monitored if combined with pharmaceutical anti-seizure meds because it can change the concentrations of the other drugs in the body, rendering the drugs less — not more — effective in preventing seizures.
CBD use alongside chemotherapy treatments can result in higher concentrations of the drugs for longer periods — which isn’t necessarily a good thing. In cancer treatment, the ratios and dosages are highly regulated for optimum effect and minimum toxicity.
However, CBD and THC are both known to alleviate pain from cancer and to slow the growth of cancer cells, so if well monitored, they can both potentially play a role in treatment.
At Which Dosages Does CBD Affect Other Drugs’ Performance?
The extent to which CBD affects the performance of these kinds of drugs is not entirely clear, nor is it evident what concentrations are risky. According to a report by Project CBD, it’s possible that lower doses of the cannabinoid (less than 100 milligrams) would not have much effect. For perspective, a fairly standard dose of CBD is somewhere in the range of 30 milligrams, though people can and do take much larger amounts for therapeutic purposes. Some cite the fact that, because CBD isn’t psychoactive on its own, people sometimes ingest very large servings without knowing.
When Could CBD Interactions Actually Be a Good Thing?
According to Dr. Bill Code, a physician who works with medical marijuana in Canada and author of Solving the Brain Puzzle, CBD can augment the effectiveness of painkillers like OxyContin by four to ten times, which means that pain patients seeking to taper off meds can reduce their dose without dipping into the pain zone. As long as this augmenting action of CBD is known and monitored, the cannabinoid can be instrumental in reducing pharmaceutical dependence.
Dr. Code told Civilized that if a patient adds a large amount of CBD to an existing painkilling regimen, “that’s a tiny bit risky,” because the CBD slows the breakdown of the narcotic. “So that’s why, when you’re doing this reduction of the narcotic, it’s better to have some THC in there, too,” he said. In fact, for pain relief — including the use of cannabis in conjunction with opioids — Dr. Code will often recommend a 4:1 ration of THC to CBD because the THC will not interfere with the liver’s processes the way cannabidiol does.
How Dangerous Is It?
It depends on whom you ask.
Yoon emphasized how limited the data currently is on CBD-drug interactions, but also cited a 2016 study by Ethan Russo, which found CBD to be, “safe and well tolerated in humans, even in complex drug regimens with opioids, tricyclic antidepressants, and anticonvulsants.” However, she said, because potential harm is present, it’s vital to work with a knowledgeable practitioner when seeking to combine certain classes of meds and CBD. The risk is particularly strong, she said, for the elderly, and for those with compromised liver or kidney function.
Dr. Tishler advises that patients taking the aforementioned drugs avoid products high in CBD. However, he added, trace amounts found in flower or many vape products are not likely to cause harm.
According to the report from Project CBD, the risks are on part with “mis-dosing the other drug(s) that a patient is taking.” The dangers likely increase with higher doses of CBD (particularly isolates, as opposed to full-spectrum compounds) taken in combination with a pharmaceutical “that has a very narrow window between its therapeutic and toxic levels.”
A patient's metabolism may also play a role: The slower one's metabolism, the longer the effects of the cannabinoid (or another drug) will last in the body, which could influence a patient's level of risk when taking multiple substances at once.
Do the Types of CBD and Modes of Consumption Matter?
In short, yes. Whole-plant CBD extracts in this case are safer because, with the entourage effect attributed to the mix of THC, CBD, and other plant compounds, a patient may need fewer milligrams of the product to achieve the desired effect. It’s perhaps counterintuitive that products containing some THC may actually be safer than CBD isolates and single-molecule CBD extracts for those taking prescription meds—but, according to experts on the subject, it’s because THC does not have the same effect on the liver enzymes that CBD does.
Inhaling cannabis also poses less risk for drug interactions than orally consuming it because of differences in the liver’s metabolizing process for the two routes. Timing may also matter. Though research on this subject is still in its infancy, there’s some evidence to suggest that consuming CBD several hours after taking a pharmaceutical may reduce its potential interactions.