Is Smoking Weed as Bad for Your Lungs as Smoking Cigarettes or Vaping?

Use of cannabis (also known as marijuana) is increasing globally, and smoking is the most popular way to consume it. 

Smoking cannabis can damage your lungs. It can also have other harmful effects on your health. But how do these risks compare to smoking cigarettes or vaping cannabis oil? 

Here’s what the latest evidence tells us.

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How does smoking marijuana affect your lung health?

Smoking any substance can cause inflammation and damage to your airways and lungs. Any substance that is burned or heated releases toxic chemicals. When you inhale those chemicals, it causes direct and immediate irritation to the lung’s delicate tissues.

Cannabis smoke is no exception. When burned, cannabis releases chemicals that are harmful to the lungs. In fact, apart from nicotine, cannabis smoke contains similar toxins to cigarette smoke. It has even higher concentrations of some toxins and causes more lung inflammation and damage than tobacco smoke.

It shouldn’t be surprising, then, that smoking cannabis can cause symptoms of acute and chronic bronchitis, such as: 

• Persistent cough

• Increased mucus production (wet cough)

• Wheezing (noisy breathing)

• Shortness of breath

Interestingly, the effects appear to go away when a person stops regularly smoking cannabis. 

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. 

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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.  

Does smoking cannabis cause ‘bong lung’?

Some heavy cannabis smokers develop areas of severe damage in their lungs that cause air pockets. This irreversible form of emphysema (bullous emphysema) causes severe breathing difficulties. 

The evidence for the link between so-called “bong lung” and cannabis use is — you guessed it — unclear. There have been multiple case reports in individuals who heavily use cannabis (not only in people who use bongs), but it’s not known if cannabis is the main culprit.

Which way of smoking marijuana is most harmful to the lungs?

There are many ways to smoke cannabis. Below, we’ll go into a few common methods. But the bottom line is that no matter how you smoke it, burning cannabis creates toxic chemicals that damage the lungs. The damage can be worse if you’re burning cannabis that contains pesticide residue.    

Blunts and spliffs

Blunts and spliffs are common terms for products that combine cannabis with tobacco. Blunts are cigars that have been filled with cannabis and wrapped in tobacco leaves. Spliffs are cigarettes with a blend of tobacco and cannabis. 

Smoking cannabis with tobacco is the most harmful way to smoke cannabis. It exposes you to higher levels of toxic chemicals. Smokers of both cannabis and tobacco have been found to have more lung damage than people who only smoked cannabis. They also have a higher risk of respiratory symptoms including persistent cough and developing chronic obstructive pulmonary disease (COPD).

Smoking cannabis with tobacco is also more habit-forming. Lab studies using rodents have shown that nicotine makes THC more addictive. People who combine the two substances have a higher chance of developing cannabis use disorder, according to survey studies.

Bongs, pipes, and joints

Bongs, which are water-filled pipes, are commonly used to smoke cannabis. Cannabis is also smoked in dry pipes. Cannabis cigarettes, called joints, contain ground cannabis wrapped in paper. 

There is no evidence that using a bong is safer than other smoking methods. One study found that water pipes reduced THC strength but did not reduce the amount of tar found in cannabis smoke. Evidence from tobacco studies also shows that water filtration does not reduce the amount of toxins you inhale.

Is cannabis vapor safer than smoking cannabis?

Cannabis vaporizers offer the safest way to inhale cannabis. But they are still not considered safe. 

Cannabis vaporizers heat cannabis without burning any material. This reduces the amount of toxic chemicals inhaled. 

But these electronic drug delivery devices (also-called “e-cigarettes”) have been clearly linked to serious (and sometimes fatal) lung injuries called EVALI (e-cigarette or vaping-associated lung injury).  

Most EVALI cases are tied to daily use and a large number of puffs — common behaviors for vape users. 

Which way of smoking marijuana is least harmful to the lungs?

Smoking cannabis is always damaging to your lungs. Smoking involves the burning of plant material, which creates toxic chemicals that are inhaled into your lungs.

The best way to consume cannabis without exposure to toxic smoke is to stop smoking. Edible and topical cannabis products do not damage your lungs. 

Is smoking weed safer than smoking cigarettes?

Cannabis and tobacco cigarettes are the two most commonly smoked substances in the world. And the smoke of both substances shares many similarities: They both contain dangerous toxins like carbon monoxide and cancer-causing chemicals called carcinogens.

But the two substances are smoked in very different ways:

• Cannabis smokers usually inhale much deeper than cigarette smokers. This potentially exposes their lungs to more toxins. One study found that smoking one cannabis joint exposed users to three times the amount of tar and five times the amount of carbon monoxide compared to smoking one cigarette.

• But cigarette smokers often smoke more cigarettes a day than cannabis smokers. This could expose cigarette smokers to more toxins in the long run. Cigarettes damage the delicate tissue in your lungs. They also cause you to have less air flow into and out of your lungs. And long-term cigarette smoking causes severe lung damage including lung cancer, chronic bronchitis, and emphysema. 

Overall, scientists believe that smoking cannabis has lower risks for lung damage than smoking cigarettes. But this doesn’t mean that it’s safe. And there is a lot we still don’t know about the long-term effects of smoking cannabis.

Why trust our experts?

Written by:

Lester Black

Lester Black is an independent journalist. His work has been featured in Popular Mechanics, The Guardian, and FiveThirtyEight.com.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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