Chronic obstructive pulmonary disease (COPD) is connected to breathing irritants. For this reason, researchers have been curious about a link between COPD and marijuana. Marijuana use is not uncommon. A national survey in 2015 showed that around 35 percent of high school seniors reported using marijuana in the previous year. About 6 percent said they used it on a daily basis, while reported daily use of tobacco was just 5.5 percent.

COPD is an umbrella term that describes chronic lung conditions such as emphysema, bronchitis, and asthma-like symptoms. It’s a common condition in people who have a history of smoking. In fact, it’s estimated that 90 percent of people with COPD have smoked or currently smoke. In the United States, 30 million people have COPD, and half of them don’t know.

So could smoking marijuana increase your risk of COPD? Read on to learn what researchers have found about marijuana use and lung health.

Marijuana smoke contains many of the same chemicals as cigarette smoke. Marijuana also has a higher combustion rate, or burn rate. The short-term effect of smoking marijuana may depend on the dose. However, repeated and consistent use of marijuana may increase the risk of poor respiratory health. Studies have found that smoking marijuana long-term can:

  • increase coughing episodes
  • increase mucus production
  • damage mucus membranes
  • increase risk of lung infections

But it’s the habits that may play the largest role in overall lung health. People often smoke marijuana differently than they smoke cigarettes. For example, they may hold smoke longer and deeper into the lungs and smoke to a shorter butt length.

Holding in the smoke affects the amount of tar the lungs retain. Compared to smoking tobacco, studies show that marijuana inhalation techniques cause four times more tar to be inhaled. A third more tar gets into the lower airways.

Longer and deeper inhalations also increase the carboxyhemoglobin concentration in your blood by five times. Carboxyhemoglobin is created when carbon monoxide bonds with the hemoglobin in your blood. When you smoke, you inhale carbon monoxide. It’s more likely to bind to hemoglobin than oxygen is. As a result, your hemoglobin carries more carbon monoxide and less oxygen through your blood. This deprives your body of the proper amounts of oxygen it needs to function at its best.

There is significant interest in studying marijuana. Scientists want to learn about its medical and relaxation purposes as well as its direct relationship to lung issues like COPD. But there are many legal, social, and practical limitations. Factors that impact research and results include:

Marijuana’s classification

Marijuana is a Schedule 1 drug. This means the Food and Drug Administration doesn’t have current proof that the drug has a medical purpose. Schedule 1 drugs also have a high chance of abuse. Marijuana’s classification makes studying its use expensive and time-consuming.

Quality tracking

The amount of THC and other chemicals in marijuana can change based on the strain. The chemicals inhaled can also change based on the size of the cigarette or how much smoke is inhaled. Controlling for quality and comparing across studies can be difficult.

Consumption tracking

It’s difficult to keep track of how much of the active ingredients are consumed. The average person can’t identify the dose they’ve smoked. Most studies also focus on frequency of use but ignore other details that may affect health and a study’s results. These factors include:

  • joint size
  • intensity of how someone smokes a joint
  • whether people share joints
  • use of a water pipe or vaporizer

Even though research is limited for marijuana, smoking anything can be unhealthy for your lungs. Most COPD symptoms aren’t noticeable until the condition has progressed and a certain amount of lung damage has occurred. Still, keep an eye out for the following symptoms:

  • shortness of breath
  • wheezing
  • chronic cough
  • chest tightness
  • frequent colds and other respiratory infections

More serious symptoms of COPD go along with more severe lung damage. They include:

  • swelling in your feet, legs, and hands
  • extreme weight loss
  • inability to catch your breath
  • blue fingernails or lips

Call your doctor right away if you experience any of these symptoms, especially if you have a history of smoking.

Read more: Early COPD symptoms »

If your doctor suspects you have COPD, they will ask you about your symptoms and do a full physical exam.

Your doctor will use a stethoscope to listen for any crackles, popping, or wheezing in your lungs. A pulmonary function test can help your doctor determine how well your lungs are working. For this test, you blow into a tube that connects to a machine called a spirometer. This test provides important information about your lung function compared to healthy lungs. The results help your doctor decide if more tests are needed or if a prescription drug could help you breathe better.

Let your doctor know if any of these factors apply to you. COPD can’t be cured, but your doctor can help you manage symptoms with medication and lifestyle changes. For more information, read about COPD treatment options.

Read more: Are you at risk for COPD? »

Researchers are still trying to determine if smoking marijuana increases your risk of COPD. Studies on the subject are limited and have mixed results. A review of studies that examine if marijuana use causes long-term lung disease found that most sample sizes were too small for results to be conclusive.

In general, how much a person inhales of something predicts the negative effects on their lung health. For people with COPD, no method of inhalation of any substance is considered safe or low-risk.

If you want to stop smoking to decrease your risk of COPD but need to take marijuana for medical reasons, talk to your doctor. You can discuss other methods for taking it, such as prescription capsules or edibles. If you want to quit marijuana altogether, follow these tips:

Tips to quit

  1. Get the support of family and friends.
  2. Throw away marijuana and all smoking paraphernalia.
  3. Have a “quit date” a month ahead to allow yourself time to quit more gradually.
  4. Come up with alternative ways to reduce stress or induce relaxation. Try reading, yoga, meditation, or tai chi, for example.
  5. Reduce time with people who smoke or places where marijuana is being used.
  6. Look to professional outlets, such as support groups, talk therapy, or Narcotics Anonymous.
  7. Attend counseling to help manage life stressors.