Smoking cannabis and lungs: risks, studies & alternatives

Smoking cannabis: What happens to the lungs

Cannabis is smoked most frequently worldwide – either pure or mixed with tobacco. Cannabis smoke contains many of the same toxic compounds as tobacco smoke: carbon monoxide, polycyclic aromatic hydrocarbons (PAHs), benzene and tar. In addition, many users burn their cannabis cigarettes deeper and hold the smoke longer, which increases the deposition of harmful substances in the lungs.

This does not mean that cannabis and tobacco are identical in terms of lung toxicity – there are important differences. But it does mean that smoking as a form of consumption carries lung risks that are independent of cannabis pharmacology.

Bronchitis and respiratory symptoms

The best-documented risk associated with cannabis smoking is chronic bronchitis:

Cannabis and lung cancer: the data situation

Although cannabis smoke contains carcinogens, the data on lung cancer is surprisingly inconsistent:

Largest study (Hashibe et al. 2006, IARC): Meta-analysis of 6 case-control studies, n=2,200+ lung cancer patients. Result: No significantly increased risk of lung cancer in cannabis users, even with intensive use. Possible explanation: THC and CBD have antiproliferative properties in vitro.

Contrasting evidence: Some cohort studies (e.g. Aldington 2008) found increased risks with very high consumption (>10 joint years). Methodological difficulty: Concurrent tobacco use as a confounder is difficult to isolate.

Conclusion lung cancer: The risk is significantly lower than with tobacco and possibly partially compensated by anti-tumor cannabinoid properties – but a complete all-clear is not possible.

Lung function: FEV1 and vital capacity

In contrast to tobacco, moderate cannabis use does not show a consistent decrease in FEV1 (one-second capacity) in longitudinal studies. The CARDIA study (Pletcher 2012, JAMA) even found slightly increased vital capacity with low-to-moderate use over 20 years – possible reason: deep inhalation during cannabis smoking as unintentional respiratory training.

However, with high long-term consumption (daily for years), CT studies show air-trapping and signs of emphysema independent of tobacco.

Forms of consumption: Protect your lungs

Vaporizer (steaming): Temperature 170-220°C instead of combustion (~800°C). No combustion → no PAHs, no tar, drastically reduced CO. Study situation: Zuurman et al. (2008) showed equivalent effect with significantly fewer respiratory symptoms. For regular users, vaporizers are the superior form of consumption.

Oils and tinctures: No pulmonary exposure. Slower onset of action (45-90 min vs. immediately with smoking), dosage more difficult.

Edibles: No lung risk. Highly variable bioavailability (6-20 %). Risk of overdose due to delayed onset of action.

Medical cannabis inhaled: Patients with SHI reimbursement are often given flowers to vaporize (recommended devices: Volcano Medic, Mighty+).

Cannabis and pre-existing lung diseases

– Asthma: Acute smoking can trigger bronchospasms. Vaporizers or non-inhalation are mandatory.
– COPD: Smoking cannabis worsens COPD symptoms. For medical indications: vaporizer or oral use only.
– Pneumonia: immunosuppression due to chronic cannabis use is possible – increased risk of infection in high users.

FAQ: Cannabis and the lungs

Summary

Cannabis smoking causes chronic bronchitis and, with high long-term use, signs of emphysema – the risks are real smoking damage, not cannabis-specific pharmacology. Lung cancer risk is lower than tobacco and inconsistently proven. Solution: vaporizer eliminates combustion risks with the same effect. For patients with chronic diseases, oral forms of consumption (oils, capsules) are the most lung-friendly option. Cannabis on prescription is prescribed as vaporizer flowers as standard for lung diseases.