Prescribed drugs are commonplace in modern society, and the acceptance of cannabis is on the rise. It’s important to be aware of potential drug interactions with cannabinoids like CBD (cannabidiol) and THC (tetrahydrocannabinol).
What Are Cannabinoids?
Cannabinoids are the primary group of compounds in cannabis that provide rich health benefits. There are over 100 cannabinoids found in the hemp plant, of which CBD, THC, and CBN (cannabinol) are the most studied.
These cannabinoids interact to create a therapeutic synergy in the human body. This is called the entourage effect and takes place in the ECS (endocannabinoid system), promoting a sense of balance and wellbeing.
Can cannabinoids interact with prescribed drugs?
The short answer: yes, but understanding why gets a bit more complicated.
Cannabinoid-drug interactions aren’t very common, generally occur at higher doses, and aren’t always negative.
Some people have learned that CBD is a useful addition to their daily medicines, even working in combination with other prescribed solutions.
So, what causes these interactions?
The Cytochrome P450 Family
CBD influences a class of drug-metabolizing enzymes in the Cytochrome P450 family, also known as CYP450. These enzymes are involved in metabolizing over 60 percent of all pharmaceuticals.
CYPs (pronounced “sips”) are found primarily in the liver, but CYP enzymes can also be found in other organs like the lungs and intestines.
Cannabinoids can inhibit or induce a CYP enzyme, effectively altering the way your body processes drugs metabolized by those enzymes.
These effects are complex and will differ depending on the second drug introduced.
For example, if CBD or another cannabinoid inhibits a CYP enzyme, the second drug’s metabolism may be delayed.
If the cannabinoid induces a CYP enzyme, it will shorten the lifespan of the second drug due to more of that enzyme being made.
A safe first step to checking for a potential cannabinoid-drug interaction is to see if they’re both metabolized by the same group of CYPs.
Information on the ways medications are metabolized, and which CYP enzymes break down those medications, is available for any drug approved in the US.
This info allows patients and doctors to research whether the drug and cannabinoid in question are metabolized by the same enzymes.
CBD and the Grapefruit Method
Worried your medication may interact with CBD or other cannabinoids?
Cannabidiol, like other natural foods, can aid in achieving a balance and a higher quality of life.
However, compounds that affect CYP450 enzymes are also present in some produce and dietary supplements at your local grocery store.
Take grapefruit for example.
There are compounds in grapefruit that interact with the metabolism of several medications by affecting this same CYP450 family of enzymes.
Compared to grapefruit, cannabinoids—especially CBD—are more potent inhibitors of these enzymes.
If a doctor or pharmacist cautions against eating grapefruit while taking a specific medication, chances are cannabinoids can cause a drug interaction as well.
These interactions aren’t always critical, but may require a dosage adjustment or monitoring with blood tests.
How Do You Use CBD Oil?
Your chosen method of cannabinoid administration can affect which CYP enzymes metabolize them.
There are a variety of ways to use CBD oil, and your usage will vary depending on your lifestyle and health goals. The various modes of administration will also impact how long it takes for CBD to work.
CBD Vape and Inhalation
When cannabinoids are inhaled, they enter into the bloodstream through the lungs. Vaporized CBD bypasses the digestive system and has a rapid onset effect.
Any potential cannabinoid-drug interactions will likely occur in minutes. Inhaled cannabinoids interact with the CYP1 family of enzymes.
CBD vape oil is generally bonded with vegetable glycerin (VG) to make it more vaporizer-friendly. Some vape compatible CBD oil can be also be mixed with other vape juice.
CBD Edibles and Ingestion
Cannabinoids that are ingested, like CBD soft-gel capsules are first absorbed by the intestines, processed by the liver, then delivered throughout the body. It can take 2-4 hours before they’re absorbed into the bloodstream.
Ingested cannabinoids are more effectively absorbed on a full stomach, but the absorption process becomes much slower.
Ingesting cannabinoids can create more potent drug interactions because of high peak liver concentrations.
Cannabinoids taken this way have a greater effect on drugs metabolized by CYP3A.
Sublingual CBD Use
Cannabinoids taken sublingually (tinctures or oils) are absorbed by membranes under the tongue without swallowing. This method falls somewhere between inhalation and ingestion in terms of how the body processes these cannabinoids.
Like vaping, CBD used sublingually is absorbed right into the bloodstream. Any leftover amount that’s swallowed will be processed by route of ingestion.
CBD Topical Creams and Lotion
Using a CBD lotion or cream for topical application of a cannabinoid will not cause a drug interaction. Cannabinoids aren’t absorbed into the bloodstream using this method and are instead absorbed by the skin into joints.
Ask Your Doctor
If you have questions or concerns about potential cannabinoid-drug interactions, please contact your doctor.
There is still so much to learn about cannabis before its effects are fully understood, and a great need for further clinical studies.