A Systematic Review of the Effectiveness of Hydrogen Therapy in Hearing Loss.

BACKGROUND

Hydrogen (H 2 ) therapy demonstrates selective antioxidant and anti-inflammatory properties with potential therapeutic value for multiple forms of hearing loss, though consolidated evidence is still lacking.

METHODS

We conducted a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, searching PubMed, MEDLINE, and DOAJ (until March 1, 2025) for studies on H 2 treatment for noise-induced hearing loss (NIHL), drug-induced hearing loss (DIHL), radiotherapy-induced hearing loss (RIHL), and idiopathic sudden sensorineural hearing loss (ISSNHL). After screening by two reviewers, 11 studies involving human or animal subjects were included. Data were synthesized by hearing loss type, and the Systematic Review Centre for Laboratory Animal Experimentation tool assessed bias risk in animal studies.

RESULTS

In NIHL models, H 2 administration reduced Auditory Brainstem Response threshold shifts and improved Distortion Product Otoacoustic Emissions recovery, while preserving cochlear morphology via reactive oxygen species (ROS) suppression. For DIHL, inhaled H 2 protected hair cells and spiral ganglion neurons through ROS scavenging and apoptosis inhibition. Clinically, H 2 inhalation improved hearing in RIHL patients post-radiotherapy. One randomized trial in ISSNHL showed H 2 combined with standard therapy significantly enhanced hearing recovery.

CONCLUSION

H 2 exhibits protective effects in preclinical NIHL and DIHL models, and promising outcomes in clinical RIHL and ISSNHL, primarily via antioxidative and anti-inflammatory mechanisms. Further trials are required to establish optimal protocols and confirm efficacy.