Psychedelics and Respiratory Health: A Literature Review

Background: The neuropsychological effects of psychedelic compounds are well-documented; however, their respiratory activity is less clear. Since respiration is a physiologically significant process and psychedelics have increasingly attracted attention in therapies, assessing the potential effects on respiration is relevant. Methods: The present narrative literature review compiled evidence on serotonergic modulation, anti-inflammatory, and proposed bronchodilatory effects of psychedelics, as outlined in preclinical, clinical, and mechanistic studies. Targeted searches in PubMed, Scopus, and Google Scholar were used to identify sources, focusing on those that measured respiratory parameters directly or indirectly. Results: Preclinical evidence suggests that the respiratory effects of classical psychedelics might occur through serotonergic pathways of the central nervous system, regulation of airway smooth muscle tone, and anti-inflammatory mechanisms. In their studies, Nau et al. (2015) and Flanagan et al. (2020) observed rodent models of asthma with respiratory modulation based on objective measures, including flexiVent or whole-body plethysmography. Nevertheless, human studies have not confirmed bronchodilatory effects: Methodological limitations, historical legal prohibition, and the methodological focus on the neuropsychiatric outcome limit respiratory-centered studies. Discussion: Interpretation is limited by animal models, heterogeneous compounds/doses, non-standardized respiratory endpoints, and possible confounding by set/setting and acute anxiety. Human experimentation is also restricted by safety and ethics. Future research must standardize respiratory outcomes (spirometry, body plethysmography, airway resistance), prospectively define time of measurement relative to dosing, and compare routes of administration (inhaled vs. oral, intranasal, IV). This could be accomplished by combining neurophysiology (e.g., EEG/fMRI) with simultaneously recorded respiratory measures, possibly helping to elucidate central-peripheral connections. Conclusion: Although evidence in animals hints at the possible beneficial effects of classical psychedelics on respiratory health, such as anti-inflammatory effects and bronchodilation, it is unclear whether these findings can be applied to the clinical setting. Future studies should utilize strong, ethically acceptable designs that integrate objective respiratory outcomes in animal and human models and address treatment potential and safety levels.