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Is Cannabidiol (CBD) Safe? 

By Sherry Christiansen

Medically reviewed by Dr. George Gavrilos, Dr. Steven Salzman

Image of CBD extraction in dropper

Key Takeaways

  1. There is a growing body of human research studies regarding the safety of cannabidiol (CBD). 
  2. The World Health Organization reports that CBD does not have any dependence potential, nor is it known to cause health-related problems when used moderately. 
  3. CBD has mild side effects, especially when compared to prescription medications.
  4. Contraindications of CBD include a list of medications that should only be taken with CBD under close supervision of a healthcare provider.

Is Cannabidiol (CBD) Safe? 

Cannabidiol (CBD) is touted for its ability to cure everything from chronic pain to migraine headaches and arthritis. CBD is the second most prevalent active ingredient in the Cannabis sativa L plant. While CBD is an essential component of medical marijuana, it can also be sourced directly from the hemp plant—a cousin of marijuana—or manufactured in a laboratory. One of hundreds of active components in the cannabis plant, CBD does not cause a person to feel high. Rather, it’s the Delta-9-Tetrahydrocannabinol (THC) component of the cannabis plant that is psychoactive. Learn more about the difference between CBD and THC here.  According to a report from the World Health Organization, “In humans, CBD exhibits no effects indicative of any abuse or dependence potential…. To date, there is no evidence of public health-related problems associated with the use of pure CBD.” 1

Does Cannabidiol (CBD) Have Side Effects?

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CBD has mild side effects, especially when compared to prescription medications. 9, 10,11  Possible side effects of CBD include: 2

  • Dry mouth
  • Nausea
  • Fatigue
  • Drowsiness
  • Irritability
  • Reduced appetite
  • Diarrhea
  • Increase in anticoagulant (blood thinning) levels

Safety 

For safety, one of the biggest concerns regarding CBD is the fact that it is not regulated by the Food and Drug Administration (FDA) in the same way that the FDA oversees the purity, efficacy, and safety of over the counter or prescription medications. This leaves the consumer with the burden of selecting a safe and effective CBD product. As a professional healthcare provider, athletic or health and wellness coach, or other professional helping clients with their health and wellness needs, there are several factors to teach your clients that will help ensure they select a safe and effective product, including selecting a product that is:

  • Purchased from a reputable company that has each batch tested by an independent laboratory for purity, potency and safety, and provides a certificate of analysis.
  • Manufactured by a company that undergoes best practices including ISO 9001:2015 certification and Current Good Manufacturing Practices (cGNP).

Cannabidiol (CBD) Dosing Safety

Because human clinical research studies are just beginning to gain momentum, there is not a lot of data that show which dose is the most effective therapeutic dose for every medical condition, or health and wellness concern.3

Best practices include starting with a low dose, and then, if clients do not obtain the optimal effect, gradually increase the dose by small increments each week.4

Contraindications 

A contraindication is a specific situation in which a drug, procedure, or surgery should not be used because it may cause harm. A relative contraindication means that caution should be used when two drugs or procedures are used together.

Similarly to other medication, CBD has a complex pharmacokinetic (i.e., the movement of drugs within the body) and pharmacodynamic (i.e., the effect of drugs and mechanisms of their actions) properties that may adversely interact with other medications and medical conditions. Healthcare providers should consider drug-to-drug interactions (DDIs) and adverse drug reactions (ADEs) associated with CBD and employ strategies to prescribe and manage patient regimens, while considering any prescription or over-the-counter medications, and any natural or herbal supplements with the potential to interact adversely with CBD.5

CBD may compete with isoenzymes that break down certain medications. The specific enzymes that help to metabolize certain medication are CYP3A4 and CYP2D6. CBD may block these enzymes in the small intestine, causing higher blood levels of certain medications that have not been properly broken down in the small intestine. 6 The result is too much of the specific medication in the body.  There is a long list of medication which should be taken with caution, only under the supervision of a healthcare provider, when CBD is taken.  The list of medications includes those such as:

  • Angiotension II Blockers
  • Antiarrhythmics
  • Antibiotics
  • Antidepressants
  • Anticonvulsants / Anti-Seizure Medications
  • Antihistamines
  • Antipsychotics
  • Anesthetics
  • Beta-Blockers
  • Benzodiazepines
  • Calcium Channel Blockers
  • HIV Antivirals
  • HMG CoA Reductase Inhibitors (Statins)
  • Immune Modulators
  • Non-Steroidal Anti-Inflammatory Drugs
  • Oral Hypoglycemic Agents
  • Proton-Pump Inhibitors (PPIs)
  • Prokinetics
  • Steroids and Corticosteroids
  • Sulfonylureas

A full list of specific medications that should only be used with CBD under close medical supervision can be found here. 7 

High doses of CBD may mimic the adverse effects that Tylenol and other non-prescription drugs have on the liver; so it’s important to review prescription, over-the-counter, and natural herbs and supplements taken with CBD. 3  

Human Safety Studies

There have been several systematic reviews of CBD’s safety and side effects. According to Bergamaschi et al, CBD has a favorable safety profile in humans based on animal research and clinical studies. The authors suggest that more data on safety should be collected over longer periods and adverse effects should be reported in a systematic/uniform manner in order to calculate benefits and harms. 8

A 2017 Study Comparing the Safety of CBD To Other Drugs

In a 2017 study involving the comparison of CBD to other treatments used for epilepsy and psychotic disorders, CBD administration reportedly had fewer side effects. The side effects were diarrhea, fatigue, and appetite and weight fluctuations. 9

A 2020 Study on Safety Compared to Amisulpride

A 2020 study found CBD as effective as a medication called amisulpride in improving psychotic symptoms. The study reported that CBD was linked with marked tolerability and safety, when compared with amisulpride.10,11 

A 2019 Study on Long Term Effects of Topical CBD

A 2019 study reported on the long-term effect of topical (on the skin) CBD cream. The topical application was found effective for inflamed skin conditions (such a psoriasis, acne, and related scars) with no side effects being reported. 12

A 2020 Systematic Review on Adverse Effects 

A 2020 systematic review of human studies found that only mild or moderate adverse effects were reported and no adverse effects were reported in some studies. There were fewer side effects compared to other drugs. 11

Resources 

  1. Word Health Organization (WHO). Cannabidiol (CBD) Critical Review Report. https://www.who.int/teams/health-product-and-policy-standards/controlled-substances/who-review-of-cannabis-and-cannabis-related-substances Published June, 2018
  2. Bauer, B. Mayo Clinic. What are the benefits of CBD– and is it safe to use? https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/is-cbd-safe-and-effective/faq-20446700#:~:text=Though%20it’s%20often%20well%2Dtolerated,dosage%20of%20CBD%20in%20products. Updated December 18, 2020. 
  3. Grinspoon, P. Harvard Health Publishing. Harvard Medical School. Cannabidiol (CBD) what we know and what we don’t know. https://www.health.harvard.edu/blog/cannabidiol-cbd-what-we-know-and-what-we-dont-2018082414476   Updated September 24, 2021.
  4. The Arthritis Foundation. Arthritis Foundation Releases First CBD Gudeance for Adults Wiht Arthritis. https://www.arthritis.org/about-us/news-and-updates/cbd#:~:text=CBD%20should%20never%20be%20used,done%20for%20any%20new%20treatment. Updated September 24, 2019.
  5. Brown, J. D., & Winterstein, A. G. (2019). Potential Adverse Drug Events and Drug-Drug Interactions with Medical and Consumer Cannabidiol (CBD) Use. Journal of clinical medicine8(7), 989.doi: 10.3390/jcm8070989 https://doi.org/10.3390/jcm8070989
  6. Government of the District of Columiba Department of Health (DOH). Medical Cannabis Adverse Effects & Drug Interactions. https://doh.dc.gov/sites/default/files/dc/sites/doh/publication/attachments/Medical%20Cannabis%20Adverse%20Effects%20and%20Drug%20Interactions_0.pdf
  7. Penn State College of Medicine. NTI Meds to be Closely Monitored when Co-Administered with Cannabinoids. https://sites.psu.edu/cannabinoid/files/2020/06/NTI-Meds-to-be-Closely-Monitored-when-Co-Administered-with-Cannabinoids_2020_04_25.pdf
  8. Bergamaschi MM, Queiroz RH, Zuardi AW, Crippa JA. Safety and side effects of cannabidiol, a Cannabis sativa constituent. Curr Drug Saf. 2011;6 (4):237–249. doi: 10.2174/157488611798280924 https://doi.org/10.2174/157488611798280924
  9. Cite Iffland K, Grotenhermen F. An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies. Cannabis Cannabinoid Res. 2017;2 (1):139–154. doi: 10.1089/can.2016.0034 https://doi.org/10.1089/can.2016.0034
  10. Leweke FM, Piomelli D, Pahlisch F, Muhl D, Gerth CW, Hoyer C, Klosterkotter J. et al. Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia. Transl Psychiatry. 2012;2:e94. doi: 10.1038/tp.2012.15  https:/doi.org/10.1038/tp.2012.15 
  11. Larsen C, Shahinas J. Dosage, efficacy and safety of cannabidiol administration in adults: a systematic review of human trials. J Clin Med Res. 2020;12(3):129-141. doi:10.14740/jocmr4090  https://doi.org/10.14740/jocmr4090
  12. Palmieri B, Laurino C, Vadala M. A therapeutic effect of cbd-enriched ointment in inflammatory skin diseases and cutaneous scars. Clin Ter. 2019;170(2):e93–e99. doi: 10.7417/CT.2019.2116  https://doi.org/10.7417/CT.2019.2116
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