Updated: Aug 26, 2022
In 2017, the World Health Organization established that cannabidiol (CBD) is generally well tolerated and carries a good safety profile. Even more, the WHO noted that CBD has no potential for abuse or dependence. But these encouraging findings don’t mean CBD users should dose without discretion.
CBD can affect how prescription drugs work within the body. This potential for drug interactions can turn prescription medicine’s precise schedule into a guessing game. However, with proper education, many prescription drug patients can safely implement CBD into their health regimen.
Just about anything we put in our body will eventually be processed by our liver. As the body’s filter, the liver uses a slew of enzymes to remove toxins and regulate chemical levels in the blood. One of these enzymes in particular, cytochrome P450, plays a critical role in CBD and drug interactions.
Cytochrome P450 is in charge of oxidizing drugs, which means it adds an oxygen atom to the drug’s molecular structure. This makes the compound water soluble and easier for the kidneys to remove. About 60% of prescription medicine is metabolized by cytochrome CYP450, and the enzyme system is also in charge of metabolizing CBD. Even though CYP450 can process both prescription drugs and CBD, it can’t do so simultaneously.
If CBD is taken near the same time as this type of prescription medication, it can function as a competitive inhibitor of CYP450 and temporarily deactivate the liver enzyme's work on the pharmaceutical drug. Thus, CBD consumption can alter that rate CYP450 processes drugs. The effects of the prescription drug can be either inhibited or amplified. For instance, CBD can reduce the enzymatic degradation of warfarin (a prescription blood thinner) which in turn increases the duration and effect of the popular blood pressure medicine.
The amount of CBD a person ingests generally increases the likelihood of affecting a drug's metabolization, but the data remains inconsistent from patient to patient. A nominal amount may have no effect at all. However, a clinical trial found a CBD dose of 25mg significantly interfered with the metabolism of an anti-epileptic drug. However, a 2013 report from GW Pharmaceuticals found that 40mg of Sativex (a CBD and THC isolate blend) had no effect on seizure medication.
To add to the complexity of potential concerns and benefits, recent data that supports a positive a drug interaction between opioids and CBD. Cannabis works synergistically with opiates and can reduce the amount needed for desired analgesic effect. The relationship between CBD and opiates was put to the test when a 2019 study observed 53% of chronic pain patients reduce or eliminate their opioids within 8 weeks after adding CBD-rich hemp extract to their regimens with 94% reporting a quality of life improvement.
CBD isn’t the only known competitive inhibitor of CYP450. Medical professionals have commonly warned their patients to not eat grapefruit before taking such medications. That’s because bergapten (a chemical found in grapefruit) is a strong inhibitor of CYP450 activity. Comparitively, CBD is a more potent inhibitor than any chemical found in the fruit.
All of these interactions could seem prohibitive when someone is considering using CBD. But in reality, understanding CBD’s potential contraindications and synergies are crucial for healthcare professionals and the popularity of CBD ingestion continues to rise. While it may seem complex, the approach is simple: Spread out your dosing. The Realm of Caring suggests 2-4 hour cushion between CBD and prescription medicine to reduce the likelihood of drug interactions. With regular use, patients' blood samples should be taken to ensure the prescription medication dose is optimized by the attending physician.