Hydrogen: a novel strategy for preventing and treating hearing loss

FactsHydrogen selectively neutralizes harmful free radicals, protecting cochlear cells.Animal studies confirm that hydrogen can reduce hearing damage caused by noise and drugs.Clinical trials have shown that hydrogen inhalation can improve hearing in certain types of patients.Hydrogen has strong diffusivity, allowing it to penetrate barriers and reach inner ear targets.Open QuestionsWhat is the most effective delivery method for hydrogen to reach the human cochlea?Can hydrogen prevent or treat age-related hearing loss? Is experimental evidence still lacking?Can the therapeutic effects observed in small-sample studies be replicated in large-scale trials?Is long-term hydrogen therapy safe? What are its physiological impacts?Beyond its antioxidant effects, what are the specific molecular targets of hydrogen in the auditory system? Sensorineural hearing loss, often caused by irreversible damage to cochlear hair cells, is primarily mediated by oxidative stress triggered by aging, noise exposure, or ototoxic agents. Conventional treatments such as hearing aids or cochlear implants have limitations in accessibility and efficacy. Hydrogen (H 2 ), a selective antioxidant with anti-inflammatory and anti-apoptotic properties, has demonstrated protective effects on various organ systems. This review evaluates the therapeutic potential of H 2 in preventing and treating sensorineural hearing loss and aims to inform future research directions. In preclinical models of sensorineural hearing loss, H 2 administration via inhalation, injection, or drinking water reduces reactive oxygen species accumulation, protects cochlear hair cells, and improves functional hearing markers (auditory brainstem response and distortion product otoacoustic emission). Clinical trials have shown that H 2 inhalation improves hearing thresholds in patients with radiotherapy-induced hearing loss and idiopathic sudden sensorineural hearing loss. No serious side effects have been observed. H 2 's high diffusion capacity and selective reactive oxygen species-scavenging properties support its role as a promising therapeutic for sensorineural hearing loss. While animal data are robust and initial clinical outcomes encouraging, further large-scale studies are warranted to validate efficacy, optimize delivery methods, and establish clinical protocols.