The interest in cannabidiol (aka CBD) ― a nonpsychoactive chemical found in marijuana and hemp plants ― is only growing. It has made its way into our shampoos and lotions. There are CBD-infused smoothies, bath bombs and beer. There are even holiday treats (looking at you, CBD jelly beans).
Many people ― including medical experts ― say it’s beneficial in helping to manage different ailments like anxiety, sleeplessness and pain. But while CBD has been advertised as an effective way to treat a wide mix of maladies, the compound is still largely unregulated and unstudied.
“It’s the wild, wild West right now,” said Michelle Henry, a board-certified dermatologist and Harvard-trained Mohs surgeon.
Because of that, there are some questions about how it may impact a user’s life ― specifically if they’re taking drugs for other health issues. Here’s what experts know so far:
Researchers suspect CBD could interact with most medications
Little is known about how CBD could affect other medications a person is taking, according to Yasmin Hurd, a CBD researcher and the director of the Addiction Institute at the Icahn School of Medicine at Mount Sinai. Still, Hurd suspects the substance could very well negatively interact with most medications that are taken orally.
Other experts seem to agree. Nearly 60 percent of the medications on the market are metabolized through a set of liver enzymes — called cytochrome P450, or CYP450 — that are, coincidentally, the same enzymes that break down CBD, Henry explained. Previous research suggests that CBD is a very strong inhibitor of the CYP450 enzymes. This means that if you take CBD while on another medication, it could block these critical enzymes, allowing more of the medication to get into your system.
“So, let’s say you’re on a medication like warfarin or Coumadin, a really common medication we give to a lot of patients to thin their blood,” Henry said. “If [CBD] is blocking the metabolism of warfarin, that warfarin is now higher and more active and can either become toxic or cause other problems.” In the case of a blood thinner like warfarin, “other problems” could entail a traumatic bleed or a dangerous hemorrhage, she added.
The same goes for benzodiazepines (or benzos) like Xanax or Ativan, which are used to treat anxiety. If CBD is taken in conjunction with one of these drugs, it could increase the side effects and potentially cause you to feel more sedated or drowsy. In some rare cases, the drug combo may become toxic or even interfere with your respiratory system, according to Henry. Doctors suspect that certain antibiotics and even NSAIDs (think Aleve or Advil) are altered by CBD consumption as well, Hurd said.
According to the District of Columbia Department of Health, CBD can also increase the serum concentrations ― the amount of medication in your blood ― of a ton of other drugs, including antidepressants, antihistamines, antiretrovirals, calcium channel blockers and beta blockers.
You may have heard of the grapefruit rule, which suggests that the citrus fruit can impair how your body absorbs certain drugs — mainly cholesterol medications, blood pressure drugs and allergy pills. That same mechanism is no different than CBD’s, Harvard Medical School reported. According to Henry, grapefruit inhibits the same set of liver enzymes that CBD blocks. So, like CBD, grapefruit juice can boost levels of other medications in your blood.
How intensely this all plays out in your body mainly depends on the dosage of both the medication and the CBD that you’re taking, Hurd said. “If the concentration of CBD is high enough, it could inhibit the activity of those enzymes, so you would get more of the other drug getting into your system,” she added.
On the flip side, very low amounts of CBD don’t seem to have that much of an effect on how well your body processes other medications. But unfortunately, there hasn’t been enough research to determine how much CBD is considered safe.
Other factors could also influence how CBD does or doesn’t affect your medication
The timing of when you take both the CBD and any other medications can also be a factor in how the drugs may interact in your body.
“Spacing out doses of medicine does help to reduce the workload on the liver,” Hurd explained. “For example, depending on the half-life of a drug, its ability to inhibit liver enzymes might be diminished after a couple of hours depending on dose, etc., thus liver enzymes could regain sufficient function by the time a second drug is consumed later on.”
In other words, the risk of having a serious drug interaction may be lower if you take your medications and CBD at different times of the day.
Finally, everyone responds to drugs differently. Some people may be very sensitive to a particular substance, while others may have little to no reaction. Ultimately, how our bodies process medication ― and the effect it will have ― is heavily influenced by genetics, age and body size.
The form of CBD also matters
The way you use CBD — whether orally, sublingually or topically — also contributes to the interaction with medication. It all boils down to how much of the substance makes its way to the bloodstream, which varies based on the method.
An IV would provide the most direct route, Henry said, as it’s putting the drug right into your blood. Second up is using CBD sublingually — underneath the tongue — or inhaling it, followed by eating (or drinking) CBD.
When ingested, CBD has to go through the gastrointestinal system, which reduces some of the absorption in the bloodstream before it makes its way to the liver where those very important enzymes are.
The least potent route is through the skin. The amount of CBD your body absorbs and sends to the bloodstream through the skin is likely negligible, according to Henry. Therefore, chances are low that you’ll experience any sort of interaction with your medication when using CBD topically, like through a lotion or cream.
The bottom line: You shouldn’t mix without talking to a doctor first
Henry advised to stay away from CBD if you’re taking medications that are metabolized by those same liver enzymes, such as certain anti-anxiety drugs or blood thinners. If you’re unsure, it’s always smart to talk to your physician before throwing CBD into the mix. If you’re set on taking CBD, your doctor may be able to adjust the dose of your other medications. While CBD does seem relatively OK to use ― and many people find it helps with their health concerns ― you just want to be cognizant of any potential health risks.
“I do think that many people think that CBD is benign and it’s safe — and it’s relatively safe compared to so many drugs out there. However, it still has bioactive effects,” Hurd said.
Just like anything else you put in or on your body, it’s best to err on the side of caution and know, to the best of your ability, exactly what the potential side effects are.