So, a couple of times, I’ve mentioned that I generally advise my patients to not smoke marijuana.  Today, I’m going dive into the reasons why. So, let’s start with the overall effects of smoking marijuana on the lungs. Smoking marijuana on a regular basis damages your lungs in ways that are both visible and invisible to the human eye. Mainly, this damage is done to the large airways that carry the smoke from your mouth to your lungs.  And, this damage leads to increased coughing, wheezing, and shortness of breath.  It also leads to waking up in the middle of the night with chest pains. It is important to know that if you stop smoking marijuana, these symptoms will usually go away.

How does smoking marijuana affect how you’re breathing?

Research has shown that smoking marijuana could cause increases in both lung volume and lung resistance.  Ok, so what the heck does that mean? With increased resistance, the ability of the lungs to stretch is limited, which makes it really hard to breathe air in. With increased volume, the lungs are really stretched out, which makes it really hard to breathe air out. Either way smoking marijuana could potentially affect your lungs in a way that makes it difficult to breathe.

How does smoking marijuana damage the lungs?  

In one study, doctors used tiny little cameras to look inside the lungs of patients who smoked marijuana. They found that, compared to the non-smokers, the marijuana smokers had more redness, swelling, and mucus in their lungs. And, if you can imagine, the swelling narrows the airways, which makes it difficult for air to enter and leave the lungs. The build-up of mucus is from the loss of cilia.  You can think of these as itty, bitty hair-like structures that line the lungs.  And, they help to clear the lungs of mucus. Overall, the doctors saw more evidence of inflammation in the marijuana-smokers’ lungs compared to the non-smokers’ lungs.

Does smoking marijuana increase the risk of infection?  

Generally, patients that are already immunocompromised are more prone to infection from marijuana.  This includes patients with AIDS, any patient who’s had an organ transplant, and cancer patients undergoing chemotherapy.  To get the infection, the marijuana itself needs to be contaminated with bacteria or fungus.  There have been reported cases of immunocompromised patients getting pneumonia from marijuana contaminated with a fungus called Aspergillus. As I mentioned before, smoking marijuana causes a loss of the cilia that line the lungs. And, remember, cilia are those tiny little hair-like structures that clean out the lungs and prevent a build-up of mucus. Clearing out the mucus is one of the main ways that the lungs prevent infection.  But, without the cilia there, the mucus builds up, and increases the risk of a lung infection.

Does smoking marijuana increase the risk of cancer?

When it comes to smoking marijuana increasing the risk of cancer, the jury’s out.  There’s evidence that says that smoking marijuana does cause cancer.  But then, there’s research that says that smoking marijuana doesn’t cause cancer. Studies have shown that marijuana smoke does contains carcinogens, which are the chemicals that encourage the growth of cancer. Although there’s little evidence to suggest that smoking marijuana causes lung cancer in light to moderate smokers. However, the risk of getting lung cancer is significantly increased in heavy smokers.  And, a heavy smoker includes anyone who smokes more than 10.5 joints per day over the course of a year. And, when the researchers took biopsies of the marijuana smokers’ lungs, they found precancerous cells.  Precancerous cells have the potential into cancerous cells.  Sometimes they do.  Sometimes they don’t. On the other hand, research done in petri dishes and in rats and mice has demonstrated anti-tumor effects of the chemicals in marijuana. More specifically, the cannabinoids – the chemicals in marijuana – have been shown to

  1. inhibit cancer cells from duplicating themselves
  2. destroy existing cancer cells, and
  3. preventing the growth of blood vessels that supply the tumor

So it’s quite possible that the anti-tumor effects of the cannabinoids could counteract the pro-tumor effects of the carcinogens in marijuana smoke.  But, of course, more research is needed to assess this possibility. There’s an important point I want to make.  The anti-tumor effects of marijuana have been demonstrated in petri dishes and in mice and rats.  As it stands, there isn’t sufficient evidence to demonstrate the anti-tumor effects of marijuana in humans.


So, now that you know that smoking marijuana damages the lungs, check out this article, HOW TO USE MEDICAL MARIJUANA WITHOUT SMOKING IT.  It walks you through the different ways to use medical marijuana WITHOUT smoking it. 



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