COVID-19 and Cannabis Smokingand Vaping:FourThings You Should Know

COVID-19 and Cannabis Smokingand Vaping

Withthe growing attention being given to the medicaleffects of cannabis, there isgood dealof inaccurate informationcirculating on the Internet and social media about the potential positiveeffects oftetrahydrocannabinol (THC)andcannabidiol (CBD),the two major compounds in cannabis, on COVID-19. However,there is no scientific evidence that demonstratesthe benefits of either THC or CBD in preventing or treating COVID-19. On the contrary, the evidence showsthat inhaling cannabissmoke, as with smoke from other sources such as tobacco,can have negative effects on the respiratory system. A compromised respiratory system might, in turn, increase susceptibility to COVID-19 andworsen the respiratory symptoms of the diseaseamong those infected. For instance, a recent study evaluating the risk factors leading to COVID-19 complications in 78 cases of COVID-19-induced pneumonia showed that people who smoke were 14 times more likely to develop COVID-19 complications such as pneumonia compared to people who do not smoke (Liu et al., 2020).Further studies are needed to determine the extent to which cannabis smoking (or vaping) can also represent a risk factor for COVID-19-related respiratory complications.Here are fourimportant things you should know about COVID-19 and cannabis smoking and cannabis vaping:1.Cannabis smoke containsmanychemicals and fine particlesthat are known to be toxicandcarcinogenic,andto cause genetic mutations(Moir et al., 2008; Manolis, Manolis, & Manolis, 2019). These chemicalsare further known to causecardiovascular and respiratory diseases and cardiovascular morbidity and mortality (Brook et al., 2010; Pope et al., 2009; Manolis et al., 2019).When smoking cannabis, using either a joint,a bong or a pipe, individuals tend to inhale more deeply and to keep the smoke in their lungs for longer. These behaviours are intended to expose the respiratory system to greater quantities of the psychoactive ingredients in cannabis, but also result in greater exposure to toxins and chemicals that can irritate respiratory tissue (Manolis et al., 2019).2.Cannabis smoking can have negative impacts onlung health.Cannabis smoking is related to a greater incidence of chronic cough and phlegm production (National Academies of Sciences, Engineering, and Medicine[NASEM], 2017). Other respiratory symptoms, including wheezing, sore throat, chest tightness and hoarse voice,have been extensively reported with regular and heavy use of cannabis (Hancox, Shin, Gray, Poulton, & Sears, 2015; Moore, Augustson, Moser, & Budney, 2005; Taylor, Poulton, Moffit, Ramankutty, & Sears, 2000; Tetrault, et al., 2007). Long

COVID-19 and Cannabis Smoking and VapingCanadian Centre on Substance Use and Addiction • Centre canadien sur les dépendances et l’usage de substancesPage 2term cannabis smoking can worsen respiratory symptoms and lead to more frequent episodes of chronicbronchitis (NASEM, 2017). There is emergingevidence that quitting cannabis smoking can reverse some of the negative respiratory symptoms associated with its use (NASEM, 2017).3.THC from cannabis smoke or inother forms can inhibit the ability of the immune system to protect the body from foreign pathogens, thus increasing susceptibility to infections. For example,growing evidence from preclinical studies in rodents and monkeys has shown that THC is able to suppress the ability of immune system cells and “immune messengers” to modulate an adequateimmune response (Eisenstein & Meissler (2015) against foreign pathogens such as viruses. In humans, some studies have shownthat THC can inhibit the functioning of several types of immunecells in the lungs (Shay et al., 2003; Tashkin & Roth, 2006), an effect that has been suggested to alterthe immune system defences oflungs and increasessusceptibility to infections.There have not been many studies examining the effects of THC and other cannabinoidson the immune system in humans (NASEM, 2017) andmore studies are needed to confirm the effects of THC on immune competencies in both healthy and compromised individuals (NASEM, 2017). However,the large body of preclinical evidence supportsthe hypothesis that THChas a potential affect on immune functioning.4.Vaping of unregulated cannabis extracts can lead to severe lung and pulmonary illnesses.Recently, cannabis vaping products that were mostly purchased on the illegal market havebeenassociated with severe pulmonary illness,which in some cases resulted in death (Canadian Centre on Substance Use and Addiction, 2019; Centers for Disease Control and Prevention, 2020; Health Canada, 2019). While it is unknown which substanceor substances in these products led to these outcomes, the primary agent appears to be vitamin E, which is used as a thickenerin cannabinoid-infused oils. A recent study has shown that heating vitamin E acetate can produce carcinogenic alkenes, benzene and toxic ketene gas (Wu & O’Shea, 2020), chemicals that potentially played a role inthe pulmonary illnesses associated with vapingunregulated cannabis extracts containing high levels of vitamin E acetate.EightWaysto Reduce Your Health Risks1.Do not share joints, vaping devices and bongs.2.Wash your hands before putting any type of cannabis product in your mouth. 3.If possible, try to limit your cannabis use to once a week.4.Avoid taking deep inhalations and try not to hold your breathe.5.Purchase your cannabis products from licensed and regulated retailers.6.Use products that contain no more than 100 mg/g (10%) of THC content.7.Remember that cannabis can interact with your medication. Speak to your heathcare provider before using cannabis.8.If you are using cannabis for medical purpose, consult your healthcare provider withany questions you may have about medical cannabis use during the COVID-19 pandemic.For more information, visit

ConclusionsThere is emerging evidence suggesting that cannabis smoking can have negative consequences on an individual’s respiratory system and immune competences. There is no evidence that smoking or vaping cannabis can prevent, alleviate or treat COVID-19 symptoms. Cannabis smoking or vaping couldworsen the respiratory symptoms of COVID-19. The National Institute on Drug Abuse in the United States has recently warned that COVID-19 could be a serious danger for populations with substance use disorders, including people who smoke or vape tobacco or cannabis (National Instituteon Drug Abuse, 2020). Rates of cannabis use among adults aged 65 years and older has been rising in Canada. Older adults are at greater risk ofdeveloping respiratory and cardiovascular complications,and the co-occurrence of cannabis smoking and COVID-19 could increase the risk of these complications. Impaired lung function could put people who smokeor vape cannabis at risk for serious complications from COVID-19. The extent to which cannabis smoke impacts respiratory and immune health in humans iscurrently not well-known. However, in light of the ongoing COVID-19 pandemic, any behaviours that mightput an individual’s health at risk should be carefully considered;this includes smoking and vaping cannabis.More information about cannabis and its effects on the lungs and heart is coming soon in CCSA’s Clearing the Smoke on Cannabis Series.Complementary ResourcesHealthServicesand Mental Health Support Resources •ConnexOntario, Addiction,Mental Health, andProblem Gambling Treatment Service:•Ontario Telemedicine Network, Clinical Resources to Support COVID-19 andthe Use of Virtual Care:•Telehealth Ontario, Get Medical Advice:•, Online Rehab Group: Resources•Canadian Institute for Substance Use Research,Safer Cannabis Use:•Centre for Addiction and Mental Health,Canada’s Lower-Risk Cannabis Use Guidelines:—reports-and-books—research/canadas-lower-risk-guidelines-cannabis-pdf.pdf•Government of Canada,Cannabis in Canada: Get the facts: Resources•Government of Canada, Coronavirus disease (COVIC-19):

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