CannaTrials adheres to evidence-based medicine – making statements based on medical evidence.

This page is excerpted and quoted from the National Academies of Science, Engineering, and Medicine.    A Committee of over 40 experts, researchers, and reviewers in The Health and Medicine Division published a 486 page report in 2017 entitled “The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research.
If you would like to access the entire report you may do so by clicking this link.

Medical Marijuana and Respiratory Symptoms, Including Chronic Bronchitis

“Respiratory symptoms include cough, phlegm, and wheeze. Chronic bronchitis is defined as chronic phlegm production or productive cough for 3 consecutive months per year for at least 2 consecutive years (Medical Research Council, 1965). Chronic bronchitis is a clinical diagnosis and does not require confirmation by spirometry or evidence of airflow obstruction. The committee responsible for Marijuana and Medicine: Assessing the Science Base (IOM, 1999) concluded that acute and chronic bronchitis may occur as a result of chronic cannabis use.

Regular cannabis use was associated with airway injury, worsening respiratory symptoms, and more frequent chronic bronchitis episodes. There were no clear additive effects on respiratory symptoms observed from smoking both cannabis and tobacco. Cannabis smoking cessation was temporally associated with the resolution of chronic bronchitis symptoms, and a small feasibility study suggests that use of a vaporizer instead of smoking cannabis may lead to the resolution of respiratory symptoms. The committee’s findings are consistent with those reported in a recent review (Tashkin, 2013) and position statement (Douglas et al., 2015). The majority of studies relied on self-report for cannabis smoking. Many studies failed to control for tobacco, occupational, and other environmental exposures; did not control for the dose or duration of the cannabis smoke exposure; and did not use joint-years and instead based heavy cannabis exposure on exceeding a specific threshold of cigarettes. Even among studies that used joint-years, it is unclear how generalizable the findings are, given the potential high variability in tetrahydrocannabinol (THC) content from joint to joint and from year to year.

CONCLUSION 7-3
7-3(a) There is substantial evidence of a statistical association between long-term cannabis smoking and worse respiratory symptoms and more frequent chronic bronchitis episodes.
7-3(b) There is moderate evidence of a statistical association between cessation of cannabis smoking and improvements in respiratory symptoms. [1]

[1] The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research | The National Academies Press. 2017. Pages 187-192. Download the complete 486 page report.

**Important Note:  On many of the health conditions studied by NAS, there was no conclusive evidence of cannabis effectiveness from the study results they reviewed.  The authors included a long section on “research gaps.

It is the Vision and Mission of CannaTrials to fill in some of these research gaps with cannabis clinical trials using specific medical marijuana formulations and testing them in a research protocol with local patients, physicians, processors and dispensaries.  If you are interested in participating in a clinical trial, and helping improve scientific knowledge about health effects of cannabis, please click one of the buttons below on this page.

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