Cannabis smoking causes bronchitis but a surprisingly different lung pattern than tobacco

Cannabis smoking causes bronchitis and increases central airway resistance with lung hyperinflation and higher vital capacity. Unlike tobacco, there is no convincing evidence it causes COPD, despite some case reports of bullous disease and pneumothorax in heavy users. An association with lung cancer remains unproven with conflicting findings.

Narrative review of the evidence on cannabis use disorder and respiratory health, addressing bronchitis, airflow obstruction, emphysema, lung cancer, and specific lung function patterns.

With cannabis legalization increasing smoking prevalence, understanding its distinct respiratory effects (different from tobacco) is essential for clinical guidance and public health messaging.

The pattern of cannabis lung effects (bronchitis without COPD, hyperinflation without obstruction) is pharmacologically unexpected and suggests cannabis smoke components may affect airways through different mechanisms than tobacco, possibly through anti-inflammatory cannabinoid effects partially counteracting smoke-induced damage.

Narrative review. Cannabis respiratory research is limited by illegality, variable product potency, and most users also smoking tobacco. Confounding by tobacco is difficult to eliminate completely.