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FACT SHEET: Cannabis (also known as “marijuana” and “marihuana”; street names include “pot”, “dope”, “ganja”, “grass”, “weed”, “herb”, “joint”, “spliff”, “bud”, “reefer”, “Mary Jane”, “doobie”, “green”, “trees”, “flower”, “smoke”, “skunk”, “boom”, “gangster”, “sinsemilla1”, and “hashish2” [hash])

Date of Publication: October 14, 2020

Is the initiation of non-invasive dental hygiene procedures* contra-indicated?

  • No, unless:
  • the patient/client displays behavioural signs/symptoms that pose a risk to himself/herself or the dental hygienist during procedures (e.g., psychosis, extreme restlessness, aggression, etc.); or 
  • the patient/client is intoxicated or “high” and therefore is incapable of giving informed consent. 

Is medical consult advised?  

  • No, in most circumstances of cannabis use.  
  • Yes, if the patient/client shows signs/symptoms of adverse health effects of cannabis use.
  • Yes, if undiagnosed substance use disorder (abuse or dependence) or poor response to its treatment is suspected.

Is the initiation of invasive dental hygiene procedures contra-indicated?**

  • Yes, if cannabis dependency is of a type or extent that may affect the appropriateness or safety of scaling and root planing, including curetting surrounding tissue (as per Ontario Regulation 501/107). [This will be a small minority of patients/clients who use cannabis, either recreationally or medicinally.]

Is medical consult advised? 

  • See above. 

Is medical clearance required? 

  • No, in most circumstances of cannabis use.
  • Yes, if cannabis dependency meets the proscribed initiation criteria of O. Reg. 510/107.

Is antibiotic prophylaxis required?  

  • No.

Is postponing treatment advised?

  • No, in most circumstances of cannabis use. 
  • Yes, if the patient/client is intoxicated, “high”, psychotic, extremely restless, or aggressive, or is otherwise suspect with regard to giving informed consent and/or being able to allow safe delivery of dental hygiene procedures (for both the patient/client and the dental hygienist). If one or more of these conditions exist, procedures should be deferred until safety can be ensured and capacity for informed consent restored. 
  • Yes, if the patient/client has ischemic heart disease or heart failure  that is currently exacerbated by cannabis use, or if the patient/client is otherwise medically unstable. Dental hygiene procedures should be deferred until the patient/client is medically stable.
  • Yes, if the patient/client is unwilling or unable to comply with treatment.

Oral management implications

  • With recent legalization of recreational cannabis in Canada3, the dental hygienist may see an increasing number of patients/clients who use marijuana (or at least acknowledge using it).
  • The dental hygienist needs to consider the treatment implications of both systemic and oral adverse effects of recreational and medicinal cannabis use.
  • The patient/client’s medical history-taking should include reviewing medically prescribed and non-prescribed drugs, including cannabinoids, in a judgement-free fashion. If cannabinoids are medically prescribed or otherwise used medicinally, the underlying medical condition(s) should be ascertained. Occasional recreational/medicinal use of marijuana should be distinguished from regular use (e.g., greater than two marijuana cigarettes per week).   
  • The dental hygienist should recognize signs/symptoms of cannabis intoxication or being “high”, because patients/clients so affected may preclude their giving valid informed consent (due to cognitive impairment) and/or safe delivery of dental hygiene procedures.
  • The dental hygienist should determine if the patient/client has “self-medicated” with cannabis prior to the dental/dental hygiene appointment.4 If so, then the care plan may need to be modified or cancelled to avoid any substance-associated behavioural problems, drug interactions, or other safety issues.
  • Verification of cannabis use may necessitate assessment of the patient/client’s vital signs, capacity to consent, etc., at every dental hygiene appointment. Patients/clients should be encouraged to avoid cannabis use prior to a dental hygiene appointment to reduce risks of bleeding and slow healing. 
  • Orthostatic (postural) hypotension can result from large doses of cannabis5, and therefore care should be taken to avoid fainting and falls.
  • Increased anxiety, paranoia, and hyperactivity resulting from marijuana use may heighten the stress of a dental/dental hygiene visit.
  • Local anaesthesia with epinephrine can potentiate cardiovascular effects of cannabis (such as elevated heart rate or prolonged tachycardia), potentially creating an unstable medical situation in certain patients/clients — particularly those with underlying ischemic heart disease.
  • Cannabis use can increase the drowsiness caused by some drugs, including benzodiazepines, barbiturates, narcotics, and some antidepressants.
  • Risk of bleeding is increased when cannabis is taken with other drugs that increase the risk of bleeding (e.g., acetylsalicylic acid [ASA] and other nonsteroidal anti-inflammatory drugs [NSAIDs], antiplatelet drugs, and anticoagulants [blood thinners]).
  • Blood glucose levels may be altered by cannabis use, and therefore caution is advised for patients/clients who take other drugs that affect glycemia (particularly diabetes medications).    
  • The cannabinoid delta-9-tetrahydrocannabinol (THC) is an appetite stimulant, which can foster increased consumption of cariogenic foods. THC also has immunosuppressive effects that may contribute to opportunistic infections of the mouth. 
  • As for any patient/client who smokes, the dental hygienist should be particularly vigilant in checking for signs/symptoms of oral cancer in persons who smoke cannabis.

Oral manifestations

  • Inhalation is the most common route of administration of recreational cannabis. Poor oral health can result from chronic smoking and vaping of cannabis, which contribute to xerostomia and/or neglect. Risk of candidiasis  and other oral infections is consequently increased.
  • Periodontal disease is increased in patients/clients who smoke cannabis, and periodontitis may present at an earlier age in cannabis users.
  • Stained teeth result from smoking cannabis, similar to smoking tobacco.
  • Dental caries, stomatitis, erythematous gingivitis, and gingival hyperplasia occur relatively frequently in patients/clients who inhale cannabis.
  • Uvulitis, leukoplakia, oral papillomas, and alveolar bone loss are less common sequelae of inhaling cannabis.
  • Smoking or chewing marijuana affects the oral epithelium, and clinical signs include erythema, leukoedema (grayish-white lesion), and hyperkeratosis. 
  • Squamous metaplasia results from chronic smoking, and risks of oral cancer and neck cancer are also increased. 
  • Medical cannabis in the form of nabilone (capsule form) has the following oral side effects:
    • xerostomia;
    • aphthous stomatitis; and
    • dysgeusia (altered taste).
  • Medical cannabis in the form of nabiximols (oromucosal spray) has oral side effects as follows:
    • xerostomia;
    • ulceration;
    • glossodynia (sore tongue);
    • reversible sublingual white lesions (possibly related to the peppermint agent);
    • pharyngitis (including throat irritation);
    • oral pain; and
    • dysgeusia. 

Related signs and symptoms

  • Marijuana is a green, grey, or brown mixture of dried, shredded leaves, flowers, stems, and seeds of the hemp plant Cannabis sativa. The two main cannabinoids from the cannabis plant are:
    • delta-9-tetrahydrocannabinol (THC), which produces a psychoactive effect or “high”; and 
    • cannabidiol (CBD), which has anti-inflammatory and analgesic properties (and is not psychoactive). 
  • Cannabis is a commonly used recreational drug.6 It is also used medicinally7 for a variety of health conditions, including temporomandibular joint disorder, trigeminal neuralgia, nausea, glaucoma, chronic pain (particularly neuropathic pain), spasticity (e.g., in multiple sclerosis), epilepsy, obesity, fibromyalgia, Alzheimer’s disease, addiction, and autoimmune disorders such as Crohn’s disease.  However, medicinal use is controversial for most conditions, given that scientific evidence is weak or lacking.
  • Cannabis is consumed in a variety of ways:
    • via inhalation, including smoking, vaping, and “dabbing”;8
    • orally, including swallowing and eating (involving edibles such as baked goods and candies);
    • topically; and
    • via suppositories/tampons.
  • Short-term use of cannabis can manifest in the following acute signs/symptoms: relaxation; euphoria; slowed reaction time; confusion; impaired balance and coordination; bloodshot eyes; dilated pupils; increased appetite; difficulty with concentrating, learning, and memory; tachycardia; cough, bronchial hyperactivity, and frequent respiratory tract infections (when smoked, vaped, or otherwise inhaled); anxiety; panic attacks; sensory and time distortions; psychosis; and possible mental health decline.
  • Long-term smoking of cannabis can cause chronic bronchitis (manifesting as cough, sputum production, wheezing, shortness of breath, and chest tightness), and it elevates risk of chronic obstructive pulmonary disease and lung cancer9 (when smoked).10 Risk of cardiovascular disease is also increased, including angina, myocardial infarction, and stroke.
  • Asthma may be triggered when marijuana users hold smoke in their lungs.
  • Given the autonomic effects of cannabis (including tachycardia and reduced peripheral resistance), use may be harmful to persons with pre-existing ischemic heart disease or heart failure.
  • Other reported complications linked to cannabis use include: hyperemesis11; acute kidney injury; seizures; mania; and self-harm and suicidal behaviour.  
  • Cannabis use during adolescence and early adulthood is harmful to the developing brain, with adverse effects on memory, cognition, and motivation. Risks of schizophrenia, depression, and anxiety disorder are also increased.
  • Cannabis use during pregnancy is linked to low birth weight, as well as increased risk of cognitive and behavioural problems in offspring; these problems include adverse effects on memory, attention, and problem-solving.  
  • Cannabis is potentially habit-forming and addictive12, and chronic use can lead to cannabis use disorder13. Heavy use can manifest as extreme changes in mood, trouble concentrating, and memory problems.
  • Chronic use of cannabis followed by quitting can result in withdrawal signs/symptoms. These include cannabis craving, irritability, anxiety, increased aggression, restlessness, increased anger, sleeping difficulty, strange dreams, depressed mood, decreased appetite, sweating, shakiness, headaches, abdominal pain, and nausea.
  • Illicit cannabis is more likely to vary in dosage and potency — and contain potentially harmful pesticides and other additives or contaminants — than cannabis legally acquired in Canada. Therefore, there is increased risk of psychosis and other overdose- or toxicity-related signs/symptoms.

References and sources of more detailed information

Date: October 2, 2020


1 Sinsemilla is high potency marijuana derived from female plants that are kept seedless by preventing pollination.
2 Hashish is a concentrated form of cannabis made from the dried resin (“kief”) of the female plant. Hash is typically consumed by inhaling from a small piece via bong, pipe, vaporizer, or joint, or by oral ingestion
3 In 1999, the Canadian government sanctioned the first legal users of medical marijuana, and in 2001 the government expanded its uses to a shortlist of medical conditions. In 2014, the federal government allowed licensed producers to sell cannabis to persons with a physician’s approval. By mid-2017, nearly 168,000 medical users were purchasing edible oil (which can be ingested directly or put into food) or dried marijuana (which can be smoked or vaporized). In 2018, legalization was expanded to include recreational use, with certain restrictions. In Ontario, the regulatory regime for recreational cannabis is similar to that of tobacco and alcohol, including minimum age of 19 years for purchase, possession, and use; the production and sale of medical cannabis continues to be federally regulated.
4 When cannabis is smoked or vaped, its effect is almost immediate and may last several hours (depending on how much has been consumed). When ingested orally, the effect is felt in about an hour after ingestion and lasts longer than when it is smoked.
5 The autonomic effects of cannabis included decreased peripheral resistance in the circulatory system.
6 Prior to legalization, cannabis was the most commonly used illegal drug in Canada. Almost half of Canadians aged 15 years and older have used cannabis at least once, with 12% having used it in the past year (and of this 12%, 24% of users stated they used cannabis for medical reasons [2015 statistics]).
7 Two prescription cannabinoid medications currently available in Canada are nabilone (a synthetic cannabinoid similar to THC, which is a capsule primarily used as an antiemetic agent to reduce chemotherapy-induced nausea and vomiting) and nabiximols (an oromucosal spray — a combination of cannabis-derived THC and CBD — used mainly as an analgesic for patients/clients with cancer or neuropathic pain and spasticity of multiple sclerosis). Cannabinoids have also been promoted by some advocates as oral care products targeting inflammation and containing a natural antiseptic; mouthwashes, toothpastes, and lip balms derived from industrial hemp (typically containing CBD but no THC) are commercially available, although their efficacy is controversial.
8 Dabbing involves inhaling vapours from concentrated forms of cannabis (i.e., high potency extracts and oils) that are made by an extraction method using butane gas. “Dabs” (also known as butane hash oil [BHO], “budder”, “earswax”, and “honeycomb”) are more potent than conventional forms of cannabis, because they have higher concentrations of the psychoactive compound THC.
9 According to some authorities, the average joint contains the same amount of tar as 10 to 20 tobacco cigarettes.
10 The long-term, direct health effects of vaping — a relatively new consumption method — are expected to take many years to become apparent.
11 Hyperemesis is prolonged or severe vomiting.
12 About 9% of recreational users become addicted, with this statistic rising to 17% for persons who started using marijuana in their teens. Because today’s marijuana typically contains more THC than in the past (and street pot is sometimes laced with opioids such as fentanyl), it is more addictive now.
13 “Cannabis abuse” and “cannabis dependence” were combined in DSM-5 (Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association) into a single entity named “cannabis use disorder”. This disorder is defined as a problematic pattern of cannabis use leading to clinically significant impairment or distress, as manifested by at least two or more of the following during a 12-month period: use of larger amounts of cannabis than ever intended or use is prolonged beyond what was intended; difficulty cutting down or controlling cannabis use; strong cravings for cannabis; failure to fulfill role obligations at work, school, or home; continued cannabis use despite adverse effects on relationships; cessation or curtailment of important social, occupational, or recreational activities due to cannabis use; recurrent cannabis use in situations where doing so is physically dangerous; continued cannabis use despite physical or psychological health problems; tolerance (i.e., increasingly large amounts of the drug are required to get the same desired results previously obtained from smaller amounts); and uncomfortable signs/symptoms upon cannabis cessation (i.e., withdrawal).

* Includes oral hygiene instruction, fitting a mouth guard, taking an impression, etc.
** Ontario Regulation 501/07 made under the Dental Hygiene Act, 1991. Invasive dental hygiene procedures are scaling teeth and root planing, including curetting surrounding tissue.