Dr. McIntrye, who co-authored a 2018 study that concluded that healthcare providers need more information about drug-drug interactions with CBD and psychotropic medication, says much of the information out there is confusing and contradictory. Therefore, he echoes Dr. Alloway’s statement that it is absolutely prudent that patients clear the use of CBD with their doctor before giving it a go.
“Herbal products are drugs,” says Rita Alloway, Pharm.D. , research professor of nephrology at the University of Cincinnati College of Medicine. “Just because [something] is herbal … doesn’t mean it can’t interact with any of the pharmaceutically manufactured drugs that you may be taking.”
Are the concentrations in commercially available CBD high enough to cause this interaction? The evidence doesn’t really say one way or another. Dr. Alloway’s research involved a high dosage of CBD that wouldn’t be found in a retail product. However, it “highlights that a drug interaction is there,” she says. Plus, tacrolimus is metabolized in the body by a group of enzymes called cytochrome P450 and CBD is a known inhibitor of this process. What does that mean? If CBD inhibits the metabolism of tacrolimus, the patient can end up with too-high levels of tacrolimus in the body. In light of this, she urges anyone taking tacrolimus to speak with their transplant team before using CBD. Don’t get your hopes up, though—using herbal remedies, particularly those with potential interactions, is generally frowned upon by doctors looking after transplant recipients (including Dr. Alloway).
Does CBD interact with medications?
If you’ve visited a store that sells health and beauty products lately, you may have noticed that products containing CBD, or cannabidiol, seem to be all the rage. Oil, chocolate, supplements, even carbonated beverages, are filling up shelves—enticing shoppers with claims that using one of these products will cure insomnia, alleviate anxiety, reduce inflammation, or treat PTSD.
While CBD is one of the active ingredients in marijuana, using CBD itself will not get you high (the component that does that is called tetrahydrocannabinol, or THC). CBD is really just a molecule within the hemp variety of the cannabis plant, and there is at least some anecdotal evidence and preliminary research suggesting that the extraction created from this molecule has some health benefits.
Despite the not-so-great news about CBD for patients using tacrolimus, for some people, CBD is actually life-changing in a positive way. In 2018, for example, the CBD-derived medication Epidiolex received FDA approval for the treatment of Lennox-Gastaut syndrome and Dravet syndrome, two very rare and very severe forms of epilepsy.
CBD is thought to act on certain receptors in your brain and other parts of the body, in ways that could relieve pain, or help certain health conditions, like childhood seizure disorders. However, as with any “natural” product, the fact that it comes from plants doesn’t automatically render it innocuous. For some people, particularly those taking certain prescription medications, using CBD is risky. It has anticoagulant effects that can thin blood; it can also modestly lower blood pressure. These effects could be dangerous for people with certain medical conditions.
Unlike tetrahydrocannabinol (aka THC, the chemical in marijuana responsible for the plant’s mind-altering effects), CBD does not get users high. But it’s gaining popularity as a pain reliever and for its other possible health benefits.
But most of what doctors know about CBD is anecdotal, according to Donald Abrams, M.D., an oncologist at Zuckerberg San Francisco General Hospital who has been researching cannabis for more than 20 years. And for most health problems, CBD’s benefits are more conjecture than proof.
Americans are turning to this cannabis product for its possible health benefits, despite little guidance on how to use it
Van Dyken’s experience with CBD may be emblematic of a larger trend. In a recent Consumer Reports nationally representative survey of 1,003 adults, 13 percent of American adults said they had used CBD to treat a health issue; of those, nearly 90 percent said it helped. And a July 2018 study in the journal Cannabis and Cannabinoid Research found that most people who try CBD for health problems learn about it through friends, family, or the internet—not from their physician.
4. Use CBD to supplement conventional care, not necessarily replace it. Experts don’t recommend that you use CBD instead of your prescription medications to treat serious conditions such as cancer, multiple sclerosis, or Parkinson’s; rather, CBD could serve as an adjunct therapy when used cautiously and with your doctor’s knowledge. “The majority of the time patients are not able to, or are not recommended to, switch from their prescription medications to just CBD,” says Ranga Krishna, M.D., chief of the neurology-stroke service at New York Community Hospital in Brooklyn and founder of CBD Databank, an online platform that collects and shares data on the medical use of cannabis. The risks of replacing any proven conventional treatment with an alternative unproven therapy, such as CBD, have not been well-studied.
Now, Van Dyken, who told her doctor about the relief she has found with CBD—and who recently became a paid spokesperson for Kannaway, a cannabis company—says she doses herself with CBD every morning. And she has given up cortisone shots and other prescription treatments.
Thyroid medication is used to treat thyroid disorders, most commonly hypothyroidism (an underactive thyroid) via thyroid hormone replacement, and hyperthyroidism (an overactive thyroid) via anti-thyroid medication. Different medications achieve these objectives through different pathways in the body. Side effects of thyroid hormone replacement therapies include chest pain, anxiety, headaches, and vomiting. While rare, anti-thyroid medication side effects can include rash, itching, fever, aches, and headaches.
No studies have examined potential interactions between CBD and metoprolol. However, some placebo-controlled research conducted on healthy people at the University of Nottingham in England and published in 2017 in the journal JCI Insight has linked CBD with decreased blood pressure when taken on its own. For patients taking metoprolol, however, the combination with CBD could potentially have negative impacts on blood pressure.
Should I take CBD with thyroid medication?
CBD’s documented effects on liver function and enzymes that metabolize several medications are relevant when considering whether or not to consume CBD with certain drugs. CBD acts on the same metabolites as grapefruit — therefore, many of the prescription drugs that carry grapefruit warning labels may have similar risks when taken with CBD.
In 2017, researchers at the University of Alabama, Birmingham, conducted a study published in Epilepsy & Behavior Case Reports which showed that CBD increases the effects of drugs used for blood-thinning by slowing down how the body metabolizes warfarin and prolonging its presence in the system. By increasing the duration of warfarin’s presence in the body, CBD could potentially exacerbate some of the associated risks.
Further, a 1993 study conducted by pharmacology researchers at the University of California, San Francisco, and published in the journal Biochemical Pharmacology, discovered that CBD, much like grapefruit, disrupts the normal function of cytochrome P450 enzymes in mice. The study postulated that while the blockage could allow patients to take lower doses of their prescriptions, it could also cause a toxic buildup of chemicals in the body. Since this study’s publication, several scientific and medical journals have published evidence of the grapefruit-like effects of CBD in humans.