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Cannabis: What dental providers need to know

Dec. 8, 2021
With more states legalizing the use of cannabis, it's important for dental providers to learn its effects on patients and how to handle this in practice.

As legislation provides pathways for the legalization of marijuana for recreational and pharmacological use, it is likely that as oral health-care providers, dental team members will encounter more patients who are using marijuana prior to their dental appointments. Not only does marijuana use affect oral health conditions, but if administering local anesthetics that contain epinephrine, practitioners should be aware of patients with increased anxiety, possible paranoia, and negative outcomes.

Breaking down Cannabis sativa L 

Cannabis is a very broad term that describes the different products originating from the Cannabis sativa L plant. For recreational users, cannabis provides mild sedation and enhances mood, whereas for clinical users, cannabis serves as an analgesic and antiemetic.1 Three of the most widely known products gleaned from the cannabis plant include marijuana, cannabinoids, and cannabidiol. Cannabinoids such as tetrahydrocannabinol, better known as THC, are active chemical compounds extracted from cannabis that possess psychotropic properties that provide a euphoric high and is considered the most important cannabinoid found within the cannabis bloom.1

The final user experience depends on the concentration of the THC and the various preparations or methods of use. While these cannabinoids are recognized as having numerous pharmacological properties in the treatment of epilepsy, pain, inflammation, and other terminal illnesses, there is a lack of strong evidence to support cannabis as a therapeutic medication.1 There are several forms of medicinal cannabis that can be consumed in food, inhaled, ingested, or applied topically, such as cannabidiol or CBD. CBD is a nonpsychotropic cannabinoid derived from cannabis and can be found in lotions, tinctures, sublingual sprays, liquids, pills, and edibles. Like many other herbal supplements, none of these are FDA approved. However, the FDA has approved one purified CBD product for the treatment of seizures in rare forms of epilepsy.2

While some research exists to support medicinal uses for cannabis, it remains at the top of the list for the most used illegal drug. Although 18 states have legalized the use of marijuana or cannabis products for recreational use, the Centers for Disease Control and Prevention (CDC) continues to identify marijuana as the most commonly used illegal drug in the United States, with approximately 22.2 million users each month.3 As cannabis gains support through social acceptance, medical and dental providers are faced with a growing list of public health concerns.

Weed my lips: The good and not-so-good aspects of cannabis use among patients

The push to legalize cannabis products     

Policy makers need to consider the positive and negative consequences of the legalization of cannabis products. There are benefits and risks associated with any substance. Although little evidence exists to support a nonpsychiatric medical diagnosis, literature does support its use to relieve nausea associated with chemotherapy, cachexia, spasticity, neuropathy, epilepsy, and rheumatoid arthritis.1  Consequentially, research identifies serious cognitive problems, such as short-term memory deficits, lack of concentration, attention disorders, and problems processing information.4 Furthermore, individuals with existing psychotic disorders are more sensitive to the psychosis-inducing and mood-altering effects of cannabis, which can increase possible relapses.4  Given these findings, prior to legalization, policy makers should consider the burdens that will be placed on an already deficient mental health and health-care system.

The largest factor for legalizing cannabis products is the purported economic benefits, increased tax revenues, job growth, and investment opportunities. In fact, cannabis sales in the US totaled more than $1.7 billion in 2019, and Colorado alone collected more than $302 million in taxes and fees on both recreational and medical cannabis products.5 Not only is it critical to look to the deleterious human cost of cannabis, it is also imperative to evaluate the cost of cannabis in concert with other drugs, both legal and illegal. Society must evaluate the financial consequences of increased cannabis use in society compared to any revenue enhancement aspects of legalized cannabis.

Increased potency and health consequences

Marijuana today is not the same as marijuana used in the 1960s. For example, before 1990, the THC level in a marijuana bloom was less than 2%. During the 1990s it grew to about 4%, and between 1995 and 2015 the THC level saw a 212% increase.6 Addiction specialists show that the more potent a drug, the stronger the possibility of addiction. Research shows that one in 10 marijuana users will become addicted. If they began using marijuana before the age of 18, that number rises to one in 6.3 Furthermore, the length and frequency of use has been linked to an increased risk of psychosis or schizophrenia in some users.7 This link is stronger if there is a family history of schizophrenia, or if marijuana use begins at a young age before the frontal lobe of the brain has fully developed.7 Given the increasing potency of THC, practitioners will continue to see an increase in patients who exhibit anxiety, addiction, depression, suicidal tendencies, and other psychosis.

Side effects of increased THC content in cannabis include:

  • Anxiety
  • Depression
  • Foggy Brain
  • Inactivity
  • Paranoia
  • Increased blood pressure
  • Increased heart rate
  • Suicidal tendencies
  • Appetite stimulation
  • Hallucinations
  • Laziness
  • Increased psychosis

While THC can be found in cannabis food products, it is stronger when a user inhales cannabis through smoking or vaping. Regardless of the method —inhalation or ingestion—cannabis enters the bloodstream and exerts effects on the body through interactions with endogenous receptors. In addition to cognitive and psychomotor impairment, immediate effects of cannabis use can include tachycardia, microcirculation disruptions, and vascular occlusive diseases.8,9 Cannabis use is known to impact virtually every system of the body, in particular the cardiovascular, respiratory, and immune systems.9,10 Therefore, it is critical to discuss possible cannabis use with dental patients prior to administering local anesthetic, providing sedation, or prescribing anxiolytics.

 Cannabis, local anesthetics, and antianxiety medications

As more states legalize cannabis, it’s more likely that you will encounter patients who may use cannabis before their dental appointments. Dental providers should be aware of possible drug interactions between cannabis and antifungals, anti-inflammatories, antibiotics, analgesics, and sedative agents. Due to the increase in blood pressure combined with a decrease in the body’s ability to carry oxygen, patients are more likely to experience a heart attack within the first hour after use.11

An increase in heart rate along with other cardiorespiratory effects creates a potentially life-threatening situation if local anesthetics containing epinephrine are administered.12 Epinephrine in local anesthetics can cause the heart rate to increase due to the dilation of peripheral blood supply, thereby decreasing the oxygen saturation in the blood. Due to the effects of cannabis on the central nervous system, patients using it may require more local anesthetic than nonusers.11 Therefore, it is logical to conclude that the additive effects of THC and epinephrine increase the risk of myocardial infarction or stroke in patients who are intoxicated or use cannabis immediately before their dental appointment.

Patients will often request medications such as benzodiazepines to aid in reducing anxiety prior to a dental appointment. If a patient is known to inhale or vape cannabis, the provider should assume that a high level of THC exists; therefore, additional antianxiety drugs should not be prescribed. Drug interactions are hard to predict without knowing the concentration of THC and the amount and frequency of use.

Dental providers should question patients about their use of cannabis during the health risk assessment interview. Although inhalation of cannabis results in a strong odor, it’s possible that patients may choose to withhold information about recent use, hence dental providers should be aware of other prominent signs and symptoms. The American Psychiatric Association indicates psychological signs of cannabis use and abuse include depression, anxiety, agitation, edginess, increased temper, irritability, moodiness, poor judgment, memory issues, uncontrollable laughing, and defensiveness.13 Physical symptoms include bloodshot eyes, dry mouth, lethargy, disheveled appearance, and lack of coordination.13

Cannabis and oral health implications

In general, cannabis users often present with poorer overall oral health than nonusers. Similar to other medications, both prescription and supplements, oral health-care providers should recognize the effects cannabis use has on oral tissues:

  • Increased caries
  • Dry mouth
  • Chronic inflammation
  • Erythroplakia
  • Increased plaque and biofilm
  • Periodontitis
  • Smoker's stomatitis
  • Hyperplasia
  • Neoplasia

Cannabis in any form has anticholinergic properties that contribute to xerostomia. Patients with xerostomia are at a higher risk for rapid decay. Cannabis users also tend to snack on foods with high cariogenic properties, therefore they would benefit from nutritional counseling, oral hygiene instructions, and prescription or topical fluoride use. As trained medical professionals, dental providers are committed to helping patients obtain optimal oral health through patient education.


As cannabis gains support for legalization across the US, medical and dental providers must be cognizant of all the public health concerns that accompany increased use. Dental providers will likely see an increase in cannabis-related dental health problems and negative drug interactions with the increase in THC levels. Dental offices should be proactive in establishing guidelines or policies that exercise caution or elect not to treat patients who actively used cannabis products on a scheduled treatment day. Dental providers should be knowledgeable in both negative and positive effects of cannabis on the body.

Editor's note: This article appeared in the December 2021 print edition of RDH.


1.  Whiting PF, Wolff RF. Deshpande S, et al. Cannabinoids for medical use: A systematic review and meta-analysis. J Amer Med Assoc. 2015;313(24):2456-2473.

2.  FDA approves first drug comprised of an active ingredient derived from marijuana to treat rare, severe forms of epilepsy. FDA. June 25, 2018. https://www.fda.gov/news-events/press-announcements/fda-approves-first-drug-comprised-active-ingredient-derived-marijuana-treat-rare-severe-forms   

3.  A closer look: How cannabis impacts health. Centers for Disease Control and Prevention. https://www.cdc.gov/marijuana/nas/index.html

4.  Zaman T, Rosenthal R, Renner J, Kleber H, Milin R. Resource document on marijuana as medicine. American Psychiatric Association Resource Document. 

5.  The State of Legal Cannabis Markets, 7th ed. Arcview Market Research. June 2019. https://www.bvresources.com/products/the-state-of-legal-marijuana-markets-7th-edition

6.  Stuyt E. The problem with the current high potency THC marijuana from the perspective of an addiction psychiatrist. Mo Med. 2018;115(6):482-486.

7.  Di Forti M, Morgan C, Dazzan P, et al. High potency cannabis and the risk of psychosis. Brit J Psych. 2009;156(6):488-491. 

8.  Volkow N, Baler R, Compton W, Weiss S. Adverse health effects of marijuana use. NE J Med. (2014);370(23):2219-2227.

9.  Goyal H, Awad H, Ghali J. Role of cannabis in cardiovascular disorders. J Thorac Dis. 2017;9(7):2070-2092.

10.  Cho C, Hirsh R, Johnstone S. General and oral health implications of cannabis use. Aus Dent J. 2005;50(2):70-74.

11.  Mittleman M, Lewis R, Maclure M, Sherwood J, Muller J. Triggering myocardial infarction by marijuana. Circulation. 2001;103(23):2805-2809.

12. Rechthand M, Bashirelahi N. What every dentist needs to know about cannabis. Gen Dent. 2016;64(1):40-43.

13.  Diagnostic and Statistical Manual of Mental Disorders. 5th ed. American Psychiatric Publishing. 2013. 

About the Author

Joseph R. Hendrick Jr., DDS

JOSEPH R. HENDRICK JR., DDS, is a licensed dentist with more than 35 years of experience in providing clinical dental care. He is active in organized dentistry in North Carolina as a past president of his local dental society, and as a current board of trustee member of the North Carolina Dental Society. He enjoys sharing his knowledge of dentistry with new dentists and hygienists and serving as a mentor to new graduates. He may be reached at [email protected] or josephrhendrickjr.com.

About the Author

Lori Gordon Hendrick, PhDc, MS, RDH, CDA, CDT

Lori Hendrick, PhDc, MS, RDH, CDA, CDT, is working toward a PhD in public administration and policy with a concentration in health policy at Old Dominion University. In addition to practicing dental hygiene, she owns Athena Dental Solutions and teaches clinical hygiene and professional development at Central Piedmont Community College. She’s a past president of the North Carolina Dental Hygiene Association, a consultant on the North Carolina Dental Society Work Force Task Force, and on the board of directors for North Carolina Caring Dental Professionals. Email Lori at [email protected].

Updated February 4, 2022