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Does Marijuana Cause Lung Damage?
Lungs image

Smoking marijuana is not as bad for your lungs as cigarettes. But it still poses some minor health risks.

Most people are aware that smoking cigarettes can lead to lung problems like impaired breathing or even cancer. While usually seen as less harmful, smoking marijuana is also thought to be bad for your lungs.

One thing is for sure: smoking pot doesn’t cause lung cancer. In fact, compounds in marijuana appear to actually protect against cancer.

But marijuana smoking is linked to mild respiratory problems. And some research has shown that heavy pot smoking could be linked to decreased lung health.

For those concerned about their lungs, vaporizing and edibles offer safer ways to consume marijuana.

Marijuana vs. Tobacco

A photo of cigarettes and marijuana related to lung damage.
(Photo: Shutterstock)

The smoke from burning cannabis contains some cancer-causing compounds that are also found in tobacco smoke.

Cannabis smoke deposits up to 4 times as much tar into the lungs as cigarettes. This is due to the way marijuana joints tend to be rolled (loosely packed and unfiltered). Since tar is a cancer-causing compound, this is a reason to be concerned.

But importantly, the smoke from marijuana also contains a set of unique chemicals known as cannabinoids (e.g. THC and CBD). A number of studies have found cannabinoids to have significant anti-cancer and anti-tumor effects.

This key difference is believed to explain the different outcomes that marijuana and tobacco have on the lungs.

Marijuana is Not Linked to Cancer

Cancer cells related to marijuana and lung damage.
(Photo: Shutterstock)

Over the past decade, two large-scale studies have set out to determine the impact of heavy, sustained marijuana use on the lungs.

One large study conducted by Dr. Donald Tashkin focused on whether smoking marijuana causes cancer.

Researchers examined the medical histories of cancer patients. They found no link between marijuana use and the development of lung cancer or other cancers when controlling for tobacco use.

The verdict? Cannabis smokers who didn’t smoke cigarettes were no more likely to develop cancer than non-marijuana users.

The fact that marijuana smoke doesn’t cause cancer was surprising. The researchers had assumed there would be a link between carcinogen-containing marijuana smoke and cancer, but there wasn’t.

THC Protects Against Lung Cancer

Studies show that THC may offer the lungs protection from the cancer-causing effects of smoke.

Dr. Tashkin explained in a 2012 interview with TIME:

“The THC in marijuana has well-defined anti-tumoral effects that have been shown to inhibit the growth of a variety of cancers in animal models and tissue culture systems, thus counteracting the potentially tumorigenic effects of the procarcinogens in marijuana smoke.”

THC may have other protective effects, too. THC’s beneficial properties may explain why marijuana users are not at risk of COPD (chronic obstructive pulmonary disease).

COPD is a long-term lung disease. It commonly affects tobacco smokers, but does not appear to occur in marijuana users.

Marijuana Smoke and Lung Health

Photo of man smoking marijuana, related to marijuana smoke and lung health
(Photo: Shutterstock)

Even though marijuana smoke is not associated with lung cancer, it may still cause harm to the lungs with heavy use. However, the impact that marijuana has on the lungs is still not completely clear.

Some studies have found that heavy marijuana use does not impair the lungs, while others have found the opposite.

When studying the link between marijuana and the lungs, researchers came up with a helpful unit of measurement for how much marijuana a person has ever smoked. They called it the joint-year. 20 joint-years means 1 joint per day for 7 years or 1 joint per week for 20 years.

A large study published in 2012 followed over 5000 young Americans for 20 years, starting in 1985. They found that even heavy marijuana use up to 20 joint-years did not impair lung capacity — a measure of lung health. Tobacco smokers, by contrast, showed a significant impairment in lung function over time.

In fact, marijuana smokers were found to have a higher lung capacity than controls. Researchers speculated that this could actually be from taking large hits of marijuana, thus expanding the lungs.

A more recent study published in 2015 found contrasting results. They found that after the 20 joint-year mark, marijuana smokers did show decreased lung capacity.

These two findings contradict each other, leaving us without a clear answer. The safest bet is to assume the worst, and consider switching to another method of cannabis consumption.

Marijuana Smoke and Bronchitis

Women suffering from bronchitis related to marijuana smoking
(Photo: Shutterstock)

Smoking marijuana is linked to bronchitis, a type of lung inflammation that results from smoke irritating the airways.

Symptoms of bronchitis include:

  • Cough
  • Phlegm
  • Shortness of breath
  • Sore throat
  • Chest discomfort

Chronic bronchitis can be seen even in patients without noticeable lung impairment.

Unfortunately, marijuana-induced bronchitis cannot be treated with medication. The best method of prevention and treatment is to stop smoking — even temporarily.

Smoking also weakens the immune defenses of the lungs, leaving them susceptible to infection. So getting a cold after a heavy smoking session may not be due to sharing a joint so much as a weakened immune system.

Harm Reduction: Vaporizing and Edibles

Photo of vaporizers and marijuana
(Photo: Shutterstock)

If you’re concerned about the health risks associated with smoking marijuana, you may want to switch to a different method of consumption.

Breathing in unfiltered smoke, such as through a pipe or a joint, is the most risky method of consuming cannabis.

Using a water bong may be slightly less risky, though it is still considered a smoking method. When using a bong, the smoke is cooled and lightly filtered by pulling it through water. This cooling lessens the irritation it causes to the lungs.


Vaporizing is an inhalation method, like smoking. But because there is no smoke, it avoids the lung problems associated with smoking.

Vaporizers heat marijuana to the point where THC and CBD are released in a gas that can be inhaled. But it doesn’t heat it enough to burn the plant matter and produce smoke.

Vaporizing avoids the toxic combustion by-products that create the harmful effects of smoke — and this has been confirmed by research.

One study conducted in 2004 compared marijuana vapor and smoke. They found that vapor consisted mainly of cannabinoids and terpenes, which are thought to be safe. Smoke, by contrast, contained known toxins and carcinogens.

A 2006 study analyzed self-reported respiratory symptoms in cannabis users. They found that vaporizer use predicted lower levels of respiratory symptoms. Thus, switching to vaporizing can help you avoid issues like chronic bronchitis.


Another option to consider is using edibles. Marijuana edibles are food products infused with cannabis, the most well-known example being weed brownies.

There are a few downsides to switching from smoking to edibles. The dose is harder to control, and the effects take some time to kick in. Nonetheless, edibles are a safer option than smoking when it comes to lung health.

Can Marijuana Be Good For Your Lungs?

Marijuana which may benefit the lungs
(Photo: Shutterstock)

Some studies suggest that THC may actually improve lung function.

THC acts as a bronchodilator in asthmatic patients when delivered in aerosol form. In basic terms, a bronchodilator is a compound causing expansion of the airways. This increases airflow to the lungs, thereby improving their functioning.

A large 2012 study found that marijuana smokers showed better lung capacity than non-smokers. Researchers suggested that this could be from taking big hits, thus stretching the capacity of the lungs.

These studies show that marijuana has potential as something that improves, rather than impairs lung health.


Marijuana smoke is significantly less harmful than tobacco smoke. Though it deposits tar in the lungs, it is not linked to the development of cancer. Scientists believe this is due to marijuana’s anti-cancer compounds.

Nonetheless, smoking marijuana is not without risk. It is linked to chronic bronchitis and lung irritation, weakened immune defenses, and possible lung function impairment in heavy users.

On the other hand, studies suggest that THC may improve lung function in some people.

Those who are concerned about the risks of marijuana smoke should consider using vaporizers or edible products.