Smoke (Less) Weed

I tell people all the time they need to smoke less weed. That may seem counterintuitive, as a physician that spends most of his time doing certifications and talking to patients about marijuana. Marijuana has been a big part of my personal wellness too! I believe that if you really love marijuana, you need to use it responsibly- and for all of us, that means smoking in moderation.

We have enough information to say that marijuana smoke is dangerous for your lungs. How dangerous, exactly, is still up for debate.

Intuitively, breathing smoke that makes you cough can’t be great. There’s also the well-known litany of vaping related illnesses and the fact that we know next-to-nothing about the long term safety of vapes.

But what does the science say?! Is there research about the negative effects of marijuana smoke on human health?


For me, the big question is: does smoking marijuana cause cancer? Right now, according to the best data we have, the answer is **probably**

Why just probably? To date, studies suffer from the same limitations: poor quality. Studying anything related to health requires the participation of honest, invested patients. It’s really hard to get people to respond honestly about a drug that is illegal! We are still dozens of years out from being able to conclusively say that marijuana causes any kind of cancer.

It’s also really, really hard to separate out the effects of marijuana smoke from the effects of tobacco smoke. Almost all studies on the topic acknowledge this! There’s a lot of overlap between the two groups of smokers, and in the future I predict a great need for people who have only smoked marijuana for research purposes.

Smoking cannabis has associations with lung cancer, head and neck cancers, and (interestingly) a kind of testicular cancer.

Marijuana smoke is known to contain many of the same harmful chemicals tobacco smoke does. Analysis of the composition of marijuana smoke shows similar amounts of cancer-causing molecules as tobacco smoke. These include pro-carcinogenic polycyclic aromatic hydrocarbons (PAHs), including benz(α)pyrene and benzanthracene (1-3).

However, there has been little definitive proof that marijuana smoke is linked to lung cancer. The research is mixed.

There are some factors that separate tobacco smokers and cannabis smokers- a typical tobacco smoker inhales a far greater amount of smoke by volume than a cannabis smoker does. Tobacco exposure is typically measured in pack years- the number of packs per day a person smokes. Most studies on cannabis measure exposure in ‘joint years’- the number of joints a day a person smokes.

With all the ways to consume cannabis these days- smoking doesn’t have to be the only way you medicate. Substitute by adding edibles and tinctures to your treatment plan and give your lungs a break.

Dr. Wong


  1. Moir D, Rickert WS, Levasseur G, Larose Y, Maertens R, White P, Desjardins S. A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chem Res Toxicol. 2008 Feb; 21(2):494-502

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