Are There Any Cannabis Drug Interactions that you Should be Worried About?

Here’s everything you need to know about cannabis drug interactions.

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Photography by Georgia Love for Herb

Cannabis is famous for being a safe drug, but could it possibly be interacting with prescription medications? We delve into the science and spoke with a doctor to find out if there are any cannabis drug interactions you should be worried about.

Does Cannabis Interact with Medications?

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Photography by Georgia Love for Herb

The short answer to this one is yes. The active compounds in cannabis, like THC and CBD, do have the potential to interact with prescription meds in a variety of ways. How? It begins in the liver, with a group of enzymes known as the cytochrome P450 system.

The cytochrome P450 system metabolizes about 60 percent of the world’s pharmaceutical drugs. But they also break down cannabinoids like CBD and THC. The issue arises when two different drugs are “fighting” for the same enzyme pathways. Cannabinoids could potentially “hog” those enzymes, inhibiting the effectiveness of prescription drugs that use the same pathways.

Interestingly, Jordan Tishler, MD and President of InhaleMD, a group of medical cannabis physicians in Massachusetts, tells Herb that some of these enzymes are really busy, while others are not. “The enzyme that breaks down CBD is one of the busy ones, whereas the one that handles THC is less so.” Basically, CBD is much more likely to interfere with your prescription meds than THC. Because we’ve already written an in-depth explainer of CBD drug interactions which you can read here, for the rest of this article, we’ll focus on THC’s potential to interact with other drugs.

THC Drug Interactions: Increasing and Decreasing the Bioavailability of THC

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Photography by Georgia Love for Herb

When you combine cannabis with some prescription medications, it can increase or decrease the bioavailability of THC. This means, that some meds could interact with your weed to make you feel more, or less, high.

Michael Verbora, MD, and member of “Doctors for Responsible Access” explains in an article for physicians that some drugs decrease or increase how THC is metabolized in the body. Therefore, certain drugs can increase or decrease weed’s effects.

Verbora writes that the drugs that could potentially increase THC’s effects include:

  •     Antidepressants like Fluoxetine
  •     Proton Pump Inhibitors like Cimetidine
  •     Macrolides like Clarithromycin
  •     Anti-mycotics
  •     Calcium Antagonists
  •     HIV Protease Inhibitors
  •     Amiodarone
  •     Isoniazid
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Photography by Georgia Love for Herb

Verbora also lists some drugs that could potentially decrease THC’s effects. This could be a problem if you are using cannabis to alleviate symptoms. You may want to up your dose of cannabis if you’re not getting relief and also taking one of the following medications or supplements:

  •     Phenobarbital
  •     Rifabutin
  •     Primidone
  •     Saint John’s Wort

Cannabis Drug Interactions: Are There any Drugs You Shouldn’t Mix with THC?

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Photography by Georgia Love for Herb

While there aren’t any lethal combinations of mixing high-THC cannabis with prescription meds, there are some potential drug interactions that you should be aware of. Verbora writes that mixing cannabis with sedating drugs such as benzodiazepines, like Klonopin, or sleeping pills, could increase the pills’ sedating effects. He warns that this could lead to increased risk of car accidents or falls, so it’s important to tread lightly when mixing cannabis and these medications. A good rule of thumb is to “start low and go slow” to see how you feel.

Another area of interest is the combination of opioids and cannabis. While cannabis could increase the sedative effects of opioids, this could actually be a good thing for those trying to reduce their opioid use. Because cannabis also helps people with pain management, inflammation, and sleep, it has the potential to help those treating pain with opioids, allowing them to lower their opioid intake while still managing their particular conditions.

Opioids are incredibly addicting and dangerous, (40k FC) Americans died in (2016?) alone from an accidental opioid overdose. But a 2011 study found that combining cannabis and opioids was increasing people’s pain relief while simultaneously reducing their opioid usage, a win-win for health and public safety.

Does Consumption Mode Matter for Cannabis Drug Interactions?

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Photography by Georgia Love for Herb

Does it affect potential drug interactions if you smoke, vape, or eat edibles to consume your cannabis? Tishler says no. “The manner of ingestion is not relevant assuming that that manner is effective itself,” he tells Herb.

However, what could affect cannabis drug interactions is the dose of THC or CBD you consume. Higher doses have a larger potential to have an effect, especially if your meds are metabolized by the cytochrome P450 system. While consumption method doesn’t matter per se when it comes to dose, many edibles and tinctures, like cannabis oils, are stronger than hitting a vape pen or a joint, and therefore could have a potentially more potent effect.

If you’re still wondering if your prescription medication could interact with cannabis and THC, there are some resources you can use. Of course, we always encourage you to talk to your doctor or find a doctor who’s open to exploring medical cannabis options. A quick tip from Herb: if your meds warn against mixing with grapefruit, then there’s a chance they’ll also interact with cannabis.

Another thing you can do is check out this interaction tool on drugs.com. It lists over 600 potential interactions between cannabis and other medications to help you figure out if your combination will have any effect. While cannabis drug interactions are possible, as long as you’re proactive and honest with your doctor, you should still be able to find doses of both that work for you.

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Photography by Georgia Love for Herb

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February 13, 2019

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