Hydrogen Gas Inhalation Reduces Eye Allergy Symptoms in Mice
- Authors
- Hideaki Sakata, Sho Kanzaki, Haruki Kai, Hikari Morii, Noriaki Haraoka, Shogo Takayama, Shimpei Seki, Yukio Sugimoto
- Journal
- Journal of Ocular Pharmacology and Therapeutics
- Year
- 2026
- DOI
- 10.1177/10807683261415800
- Study Type
- Mouse
- Outcome
- Positive
- Peer Reviewed
- Yes
- Country
- Japan
- Health Condition
- Allergic Conjunctivitis
- Body System
- Ocular
TL;DR
Hydrogen gas inhalation reduced eye-scratching behavior and eosinophil accumulation in tears in a mouse model of allergic conjunctivitis, suggesting potential anti-itch and anti-inflammatory effects.
Key Finding
In mice with allergic conjunctivitis, inhaling hydrogen gas reduced eye-scratching behavior and decreased the number of eosinophils in tears.
Summary
Researchers created mice with allergic eye inflammation (similar to allergic conjunctivitis in humans) and tested whether breathing hydrogen gas would help. Mice that inhaled hydrogen gas showed less eye-scratching behavior and had fewer eosinophils (a type of immune cell) in their tears compared to untreated mice. The researchers believe hydrogen gas works by neutralizing harmful molecules called reactive oxygen species that contribute to allergic inflammation.
Practical Takeaway
This early animal study suggests hydrogen gas inhalation may help reduce allergic eye inflammation, but this is a mouse study only—human safety and effectiveness remain unknown. Much more research, including clinical trials in people, would be needed before hydrogen gas could be considered a treatment for allergic conjunctivitis.
Abstract
Purpose: Over the past decades, the prevalence of ocular allergies has increased worldwide. Molecular hydrogen is the lightest chemical element, and in recent years, there have been multiple reports on its therapeutic effects. Animal studies have also reported the effects of hydrogen gas on various models of inflammation and circulatory disorders. Methods: In this study, we investigated the effects of hydrogen gas inhalation in a mouse model of allergic conjunctivitis. Mice were sensitized by intraperitoneal injection of ovalbumin. Local sensitization was performed once daily by instilling ovalbumin in both eyes. Conjunctivitis model mice were challenged with antigens, and eye-scratching behavior induced by antigen stimulation was evaluated. The hydrogen gas exposure group was exposed to hydrogen gas after the antigen challenge. In addition, the same mice were exposed to hydrogen gas after antigen challenge, and the number of eosinophils in the tears was evaluated. Results: An increase in eye-scratching behavior induced by antigen was observed. Hydrogen gas suppressed the increase in eye-scratching behavior. Moreover, hydrogen gas inhibited the increase in eosinophil count in tears. Conclusions: Active oxygen has a profound effect on itching and eosinophilic function. Therefore, it is thought that inhalation of hydrogen gas suppresses itching of the eye and the migration of eosinophils into the tissue by removing reactive oxygen species. Inhalation of hydrogen gas suppressed the symptoms of allergic conjunctivitis.