Cannabis side effects no one wants to talk about, Part 1: What pot does to your lungs

No one expects discomfort and pain to be components of the cannabis experience, but sometimes they are


Image at left by Visual Generation/iStock/Getty Images Plus; image at right by Pascal Kiszon/iStock/Getty Images Plus.


It might be the cannabis industry’s dirty little secret: smoking weed doesn’t always make you feel good.

I’m not talking about the psychoactive effects, mind you. Just about everyone is aware that some individuals can experience feelings of anxiety and paranoia after toking, and that certain strains can trigger these more than others.

No, I’m talking about the impact that smoking cannabis may have on the user’s body. Pot can have unpleasant side effects, but they don’t exactly get a lot of attention, especially among those with a vested interest in selling a squeaky-clean, user-friendly image of everyone’s favourite plant. Case in point: CannCentral put out a call for 420-friendly medical professionals willing to be quoted in an article about cannabis side effects. The sound of crickets has been deafening.

It is, however, a topic in which cannabis users themselves clearly have a great deal of interest. Week after week, CannCentral’s analytics tell us that the most popular article on this site is one bearing the headline “It’s not a heart attack: chest pain from smoking weed”.

That piece by Kieran Delamont, posted in July of 2019, has also generated more reader discussion than anything this site has ever published. The upshot of all those comments is that no one expects discomfort and pain to be components of the cannabis experience. Sometimes they are, though. With that in mind, let’s take a look at what the science has to say about weed’s impact on the body, starting with the lungs.

Take a deep breath, and we’ll begin.

Who do you trust?

Start poking around the Internet in search of the truth about cannabis and its effects on lung health and you’ll quickly realize two things. First of all, there’s a lot of information—an overwhelming amount. Second, a lot of what you encounter will contradict the “facts” you find elsewhere. What, then, should you believe? That depends largely on which sources you trust.

The National Organization for the Reform of Marijuana Laws (NORML), for example, has created a factsheet called “Cannabis Exposure and Lung Health”. It’s a carefully curated selection of quotes from a variety of journals, mostly contrasting the effects of cannabis with those of tobacco.

NORML cites a review of existing studies published by the journal Chest. Author Donald P. Tashkin notes that “habitual marijuana use in the manner and quantity in which it is customarily smoked” has not been shown to be “a significant risk factor for the development of lung cancer”. Chest reports essentially the same findings for chronic obstructive pulmonary disease (or COPD).

The journal does point out, however, that cannabis smoke is “associated with an increased risk of symptoms of chronic bronchitis and evidence of inflammation and injury involving the larger airways”. Tashkin also notes that pot smoke contains many of the same volatile and particulate components found in tobacco smoke. These include “a variety of chemicals (phenols, aldehydes, acrolein, etc) that are injurious to lung tissue, and carcinogens, including benzpyrene and benzanthracene”.

Let’s be perfectly blunt here: inhaling smoke—any kind of smoke—is bad for your lungs. As the Canadian Lung Association tells us, this is because “the combustion of materials releases toxins and carcinogens. These are released regardless of the source—whether it is burning wood, tobacco or cannabis.” 

More research is needed

What, then, is the truth? Can smoking cannabis cause lung cancer or not? Good luck finding a definitive answer to that question. Read through peer-reviewed medical studies, though, and you’ll find ones that seem to conclude definitively that it does. For example, in 2008, researchers in New Zealand concluded that “Long term cannabis use increases the risk of lung cancer in young adults.”

A more common—and perhaps more honest—conclusion is that we simply don’t know. As the abstract of research published in Addiction in 2020 (and cited by NORML) reads: “An association between cannabis and lung cancer remains unproven, with studies providing conflicting findings.”

This reality informs the stance taken by Canada’s largest national cancer charity. On its website, the Canadian Cancer Society states the following:

We need more evidence to know for sure if cannabis is a cancer risk. Some studies suggest that using cannabis over a long period of time may increase the risk of cancer, particularly cancers of the lung, head and neck. However, the quality of this research is not as strong as the evidence on tobacco and cancer. Other studies do not show an increased risk of cancer after long-term cannabis smoking.

The CCS concludes that more research is needed into potential links between cannabis smoking and cancer.

Photo by Serhii Sobolevskyi/iStock/Getty Images Plus.

Educate yourself

There are many unanswered questions when it comes to the effects of cannabis smoking and lung health. The science, as we have seen, is inconclusive. If you’re a cannabis smoker, then, the best way to proceed is to educate yourself as much as possible and, as always, to use your best judgment.

Listen to your body. Are you experiencing chest pain? Are you coughing or wheezing or producing increased quantities of sputum or phlegm? These could all be signs of airway inflammation or chronic bronchitis. Moreover, they are definitely an indication that you should talk to your doctor.

You may need to cut down on the amount you smoke in order to provide your body with an opportunity to heal itself. And it will; as the American Thoracic Society notes, when you give your lungs a break from smoke, “you can expect your symptoms to improve and possibly go away completely.”

Lisa Campbell, the CEO of Mercari Agency Limited, found that this approach worked for her. At the beginning of 2021, Campbell wrote that working in the weed industry as well as being a medical-cannabis patient was taking a toll on her lungs. Working from home during the COVID-19 pandemic didn’t help matters.

Lighten the load on your lungs

“I’ve tried various techniques to try and lighten the load on my lungs, switching from flower to dabs, back to flower as well as tinctures and edibles,” Campbell wrote. “No one wants to be that person coughing during COVID, even if it’s just from cannabis. 

“I needed to take a break, period,” she concluded. “The less I smoked, the better and lighter my lungs felt.”

In his aforementioned 2019 CannCentral article, Delamont cited Ottawa-based heart specialist Dr. Andrew Pipe, who advised cannabis users to consider taking it easier on their hearts and lungs by using edibles or a vaporizer. “But, here too, there are issues to keep in mind,” Delamont wrote:

With edibles, there are still effects on the blood’s capacity to carry oxygen and blood pressure. Also, dosing is more complicated. The onset of the effects of edibles takes longer, causing people to consume more. This potentially increases stresses on the heart. When vaping, you take harmful contaminants associated with smoking out of the equation, but typically take in more THC.

Clearly, there’s a lot to consider—and we have really only discussed lung health so far. Next time we’ll get to the literal heart of the matter and take a look at weed’s effect on your cardiovascular system.

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