Background. Hyperbaric oxygen therapy (HBOT) delivers 100% oxygen at supra-atmospheric pressure, producing tissue hyperoxygenation, enhanced phagocytic killing, neoangiogenesis, and immunomodulation. Although HBOT is well established in head-and-neck practice, its specific role in sinonasal disease remains poorly systematised. Objective. To reappraise the rationale, evidence, and practical implementation of HBOT in two cardinal sinonasal indications—acute invasive fungal rhinosinusitis (AIFRS) and post-radiotherapy sinonasal damage—through a rhinology-centred, multidisciplinary lens. Methods. Narrative review of articles published in PubMed/MEDLINE, Scopus, Embase, and the Cochrane Library between 1 January 1980 and 31 March 2026, conducted following the SANRA framework and combining MeSH terms for HBOT with sinonasal, mucormycosis, osteoradionecrosis, and skull-base keywords. Results. In AIFRS, HBOT addresses the angioinvasive ischaemic core, restores oxidative neutrophil killing, and potentiates amphotericin B; observational data—including the recent COVID-19-associated mucormycosis (CAM) experience—suggest a survival benefit when HBOT is added early to surgical and antifungal therapy. In post-radiotherapy injury, HBOT reverses Marx's hypoxic–hypocellular–hypovascular triad, supporting healing of osteoradionecrosis (maxillary and skull-base), soft-tissue radionecrosis, and reconstructive procedures in the irradiated bed. Sinus barotrauma, the most frequent rhinological complication, is largely preventable with structured pre-treatment ENT assessment. Conclusions. HBOT is a mechanistically well-founded, well-tolerated adjunct with a favourable safety profile when delivered by a multidisciplinary team. Sinonasal-specific prospective registries and pragmatic randomised trials are urgently needed.

Background: Hyperbaric oxygen therapy (HBOT) is proposed as an adjunct in two sinonasal conditions of high morbidity: acute invasive fungal rhinosinusitis (AIFRS) and post-radiotherapy injury. Methods: We conducted a narrative review and reported it against SANRA; PubMed/MEDLINE was searched (1980–2026; 1414 records screened, 589 retained), with Cochrane, society guidance and reference screening. Results: No randomised trial has tested HBOT against sinonasal endpoints in either indication. In AIFRS the dedicated evidence is four uncontrolled series (n = 27, level 4); none reports how many candidates were unfit to pressurise, the largest synthesis did not identify HBOT as a survival predictor, and the only randomised experiment—murine—was negative. Mycology guidance supports it with marginal strength only (C; quality III), and hyperbaric indication lists omit it. For radiation injury, Cochrane 2023 reports low-certainty benefit in head-and-neck tissue, but HOPON found no reduction in osteoradionecrosis after dentoalveolar surgery (6.4% vs. 5.7%; OR 1.13, 95% CI 0.14–8.92), and pooled DAHANCA-21/NWHHT2009-1 data were non-significant (70% vs. 51% healing); all sinonasal use is extrapolated from the mandible. Middle-ear, not sinus, barotrauma is the commonest ENT complication. Conclusions: HBOT is mechanistically coherent and may be considered case-by-case within a multidisciplinary team, but it is not a standard of care in either indication; the algorithm offered here is unvalidated.