Beneficial effects of thermal waters on respiratory diseases: a systematic review

Respiratory diseases are extremely common conditions worldwide with a high social and economic impact. The aim of this systematic review was to summarize the scientific evidence on the efficacy of thermal inhalation treatments to manage the signs and symptoms of all type of upper and lower respiratory diseases. The review was conducted according to the PRISMA recommendations. The protocol was registered in the PROSPERO platform (ID: CRD42024510869). The bibliographic search was performed using PubMed, Scopus and Web of Science databases without time limits up to January 2nd 2025. All experimental and semi-experimental studies conducted on humans, published in Italian and English, aimed to evaluate the effects of thermal inhalation treatments in the treatment of respiratory diseases were considered eligible. The quality of the studies was assessed using the CLEAR NPT scale. Overall, 27 studies were included, related to chronic and chronic-recurrent upper and lower respiratory tract diseases. The results agree on beneficial effects of thermal waters use, with an improvement in the sensation of nasal obstruction, rhinorrhea, muco-ciliary transport time and lung function parameters. The therapeutic effects determined by thermal inhalation treatments is attributed to the composition and biochemical activity of the different waters, which lead, among other effects, to a regularization of the activity of the immune system. The results, although agreeing and encouraging, cannot be definitive due to the limitations of the studies included, especially their low quality and heterogeneity. Therefore, further clinical studies should be conducted using more appropriate methodologies, study designs and statistical analysis techniques.