CBD Side Effects

CBD has potential to boost health and promote good feelings. The cannabinoid is non-psychoactive (does not cause a “high” feeling) and is non-toxic. But does it have any side effects?

A 2017 review published in the journal Cannabis and Cannabinoid Research documents the safety and side effects of CBD. It finds the most common side effects of CBD appear to be tiredness, diarrhea, and changes in weight and appetite. The author notes these side effects seem minor compared to other drugs used in similar treatments.

Another review, published in the journal Current Drug Safety, found that CBD had no adverse effects upon physiological functions such as heart rate, blood pressure, body temperature, gastrointestinal transit, and food intake.

But there is more to the story.

Liver Drug Metabolism

One potential side effect of CBD that is yet to be fully investigated is how it affects drug metabolism within the liver.

CBD has been found to interact with drug-metabolizing enzymes, such as the cytochrome P450 family. In essence, they can deactivate each other. A large portion of pharmaceutical drugs are metabolized by this enzyme, which means CBD could act as a “competitive inhibitor” and alter those drugs’ effectiveness. The extent to which it behaves this way depends on many factors, such as how much CBD is administered, the unique attributes of the individual taking the medication, and whether isolate CBD or full spectrum is used. A 2013 report on a clinical trial using a pharmaceutical CBD spray, found no interactions with P450 enzymes when approximately 40mg were administered. A subsequent clinical trial, however found 25mg of orally administered CBD significantly blocked the metabolism of an anti-epileptic drug.


CBD is not the only naturally occurring substance that can affect drug absorption. A team of Canadian scientists identified compounds in grapefruit that inhibit the expression of some cytochrome P450 enzymes. That’s why physicians often warn patients not to eat grapefruit before taking their meds. CBD, it turns out, is a more potent inhibitor of cytochrome P450 enzymes than the grapefruit compound Bergapten.

So far, the research is unclear, but it’s always smart to proceed with caution if you’re on a drug regimen that could be influenced by CBD. If you’re unsure about whether CBD could affect your medication, consult your primary care provider.


Cannabinoids have been shown to be exceptionally non-toxic. Even large doses, such as 1500mg per day of CBD, have been shown to have well-tolerated in human studies. This 10-20 times more than the typical dose recommended.

Love and light,

Mimi May

  1. An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5569602/
  2. Safety and side effects of cannabidiol, a Cannabis sativa constituent. – PubMed – NCBI https://pubmed.ncbi.nlm.nih.gov/22129319/
  3. Effects of cannabidiol in the treatment of patients with Parkinson’s disease: an exploratory double-blind trial. – PubMed – NCBI https://pubmed.ncbi.nlm.nih.gov/25237116/

Disclaimer: This content is for educational purposes only. The information provided is derived from research gathered from external sources.

Mimi May