The respiratory health benefits of quitting cannabis use.

Cannabis is the second most widely smoked substance besides tobacco. Moreover, its use in some societies has increased over the past several years [1], possibly due to changing perceptions regarding its potentially deleterious effects on health and its putative health benefits [2], as reflected by decriminalisation and legalisation for medicinal or recreational use by some regulatory authorities. A limited number of observational studies have examined the effects of cannabis on respiratory health [3–9]. These have nearly uniformly demonstrated an association between cannabis use and symptoms of chronic bronchitis [3–7, 9], particularly chronic cough and sputum production, with more variable effects on wheezing and generally negative effects on breathlessness. In addition, there is some evidence of an association with acute bronchitic episodes [3] and increased healthcare utilisation for acute respiratory illness [10]. Findings from a couple of these studies have also suggested additive effects of cannabis and tobacco smoking on symptoms of chronic bronchitis [4, 8].