Is Cannabis Bad for You Long Term? What Reddit Gets Right and Wrong
Reddit splits hard on long-term cannabis risk. Here is what the research says about dependence, lungs, mental health, and THC potency.
Short answer
Yes. Smoking cannabis sends tar, fine particulates, and irritants into the airways. Regular use is linked to chronic bronchitis, cough, and phlegm. Risk rises with joints per day and years of use.
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Edibles and tinctures do not expose the lungs to smoke. That route removes the combustion risk.
How Bad is Cannabis Compared to Alcohol: A Comparison Review
What cannabis smoke contains
Cannabis smoke is not just THC. Burning plant material produces hundreds of compounds.
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- Tar and fine particulate matter
- Carcinogens such as benzene, formaldehyde, and polycyclic aromatic hydrocarbons
- Irritants including ammonia and acrolein
The smoke carries many of the same toxins found in tobacco smoke. Cannabis users often inhale deeper and hold the breath longer. That increases tar and particulate deposition in the airways.
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Lung symptoms linked to cannabis smoking
Studies of regular users report:
- Chronic cough
- Phlegm production
- Wheezing
- Shortness of breath
- More bronchitis episodes
These symptoms overlap with chronic bronchitis. They appear in people who smoke cannabis and never smoke tobacco.
Emphysema and airway disease
A 2022 study in Radiology used CT scans. Heavy cannabis smokers had higher rates of emphysema and airway disease than nonsmokers. The signal was strongest above four joints per day. Some participants had no tobacco history.
Lung cancer
The evidence is mixed. Some case-control studies report an association between long-term heavy cannabis smoking and lung cancer. Other large cohort studies find no clear increase after adjusting for tobacco. Tobacco confounding is hard to remove because many people use both. Tobacco smoke is a Group 1 carcinogen. Cannabis smoke has no equivalent IARC Group 1 listing.
Lung function
Lung function tests in cannabis-only smokers show mixed results. A 2012 cohort study in JAMA followed 5,115 adults for 20 years. Low cumulative cannabis exposure was linked to slightly higher FEV1 and FVC. Heavy long-term use showed no gain and may narrow airways. The data do not show the steep decline seen with tobacco.
Vaping cannabis
Vaping heats cannabis oil or concentrate. It produces fewer combustion products than smoking. It is not risk-free. In 2019 and 2020, the CDC tracked 2,807 hospitalized EVALI cases and 68 deaths. Vitamin E acetate in THC vape carts was the main culprit. Vitamin E acetate is not a legal additive and shows up in illicit carts.
Lower-risk routes
Edibles, tinctures, and capsules avoid the lungs. Onset is slower, 30 to 120 minutes. Effects last longer. Oral THC goes through the liver and converts to 11-hydroxy-THC, which is more potent.
Risk factors
- Joints or bowls per day
- Years of use
- Deep inhalation and breath-holding
- Co-use with tobacco
- Asthma or COPD
Talking to a clinician
Ask about spirometry if you have a persistent cough, phlegm, or shortness of breath. Tell the clinician about cannabis use, including route and amount.