Nasal breathing (NB) and oral breathing (OB) are two modes of respiration, and the extent to which they affect respiratory muscles and brain function. The primary objective of this study was to explore the impact of NB versus OB on respiratory muscle and brain function. A literature review was conducted by searching the National Library of Medicine (PubMed) and Scopus databases from January 2000 and May 2024. One hundred twenty-six articles were retrieved from the databases searched, and at the end of the selection process, 11 articles were included in the present review. Most studies (91%) were experimental and had adult healthy volunteers
64% of the included studies focused on the effects of NB and OB on brain function, while the remaining 36% focused on respiratory muscles. A total of 313 participants comprised the population, most of whom were women (63%). Although most studies were conducted on adults, a percentage of participants (15%) were children. NB and OB elicit different brain areas and heterogeneously influence respiratory muscle function. Knowledge of the underlying mechanisms could be beneficial for, for example, personalizing respiratory and manual techniques when rehabilitating individuals with neurological or respiratory impairments.