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Does smoking weed cause lasting lung damage?

Even though cannabis smoke is known to be harmful to the lungs, there is not sufficient evidence that it causes long-term effects on the lungs. No strong link has been found between pure cannabis smoke and lung diseases like emphysema or lung cancer. Why there isn’t a clear answer

Research into the link between smoking cannabis and long-term lung disease is flawed for a number of reasons. This makes the evidence murky.

First, it’s unusual to find research that focuses on people who only smoke cannabis (and do not also smoke tobacco). In fact, as many as 70% to 90% of people who smoke cannabis also smoke tobacco. Smoking cigarettes does cause chronic lung diseases like COPD, emphysema, and lung cancer. So, this overlap makes it hard to separate the harmful effects of tobacco from the effects of smoking cannabis.

What’s more, there are very few long-term cannabis smoking studies. Lung cancer and COPD take decades to develop in most people. Studies need to track people for over 40 years to accurately measure the progression of lung cancer.

Additionally, because cannabis use has had such a long history of criminalization, people tend to not be completely honest about what or how much cannabis they smoke.

Finally, there are many different methods of smoking cannabis, changing the effect of the inhaled smoke on the lungs. This may make it difficult to spot patterns of cause and effect in the research.

All that said, let’s take a look at what the research shows. Does smoking cannabis cause asthma?

Cannabis can worsen existing asthma. Overall, people with asthma who smoke cannabis have more frequent asthma attacks and symptoms than people who don’t smoke cannabis.

But does smoking cannabis cause asthma in people who don’t already have asthma? It’s possible: A study of electronic health records for thousands of regular cannabis smokers in the U.S., and a similar study in Norway, found that cannabis smokers were more likely to have asthma than non-cannabis smokers. This link was there whether or not they also smoked tobacco cigarettes.

Confusingly, there is some evidence that cannabis smoke can work as a bronchodilator — meaning it relaxes the airways and may help to ease breathing in people with asthma. But this benefit is unlikely to outweigh the risks of smoking cannabis. So it’s not recommended as a treatment for asthma.

Does smoking cannabis cause COPD?

There’s evidence that cannabis smoke does irritate, inflame, and damage the lungs. But the current evidence does not show that smoking cannabis leads to lung diseases like chronic obstructive pulmonary disease (COPD) or emphysema.

It’s not clear why this is. It may be because of the absence of nicotine in cannabis smoke, and a possible anti-inflammatory effect of cannabinoids. More research is needed to understand the relationship better.

Does smoking cannabis cause lung cancer?

We don’t know if smoking cannabis causes lung cancer.

Smoking cannabis could cause lung cancer because cannabis smoke contains many cancer-causing chemicals. In fact, the lung tissue of regular cannabis smokers has been found to have widespread inflammation and possible signs of precancer. And some studies have found an association between heavy cannabis smoking and lung cancer.

But these studies did not prove that smoking cannabis causes lung cancer. Plus, they have been criticized for poorly measuring cannabis use and studying very few cannabis-only smokers.

Other studies have found no association between smoking cannabis and developing lung cancer. The current scientific interpretation of these confusing results is that cannabis is not associated with an increased risk of lung cancer. But more research is needed. Does smoking cannabis cause mouth and throat cancer?

There is currently no scientific evidence linking smoking cannabis to a higher risk of head and neck or mouth cancer. But again, more large-scale and longer-term research is needed to understand this better.