Hydrogen potential therapy with clinical relevanceScientific Research

Safety of Prolonged Inhalation of Hydrogen Gas in Air in Healthy Adults

Cole, Alexis R. BS1; Sperotto, Francesca MD1,2,3; DiNardo, James A. MD4,5; Carlisle, Stephanie6; Rivkin, Michael J. MD7,8,9,10; Sleeper, Lynn A. ScD1,2; Kheir, John N. MD1,2

Author Information



Ischemia-reperfusion injury is common in critically ill patients, and targeted therapy is lacking. Hydrogen inhalation reduces ischemia-reperfusion injury in models of shock, stroke, and cardiac arrest. The purpose of this study was to investigate the safety of inhaled hydrogen at doses required for clinical efficacy studies.


Prospective single-arm study.


Tertiary care hospital.


Eight healthy adult participants.


Subjects were exposed to 2.4% hydrogen gas in medical-grade air for 24 (n=2), 48 (n=2), or 72 (n=4) hours through a high-flow nasal cannula (15 L/min) in the hospital.

Measurements and main results

Endpoints included vital signs, patient and caregiver-reported signs and symptoms (stratified by clinical significance), pulmonary function tests, 12-lead electrocardiogram, mini-mental status tests, neurological examinations, and serology before and after exposure. All adverse events were verified by two clinicians outside the study team and an external data and safety monitoring team. All eight participants (18-30 years; 50% female; 62% non-Caucasian) completed the study without early discontinuation. No patients experienced clinically meaningful adverse events. Compared with baseline measurements, vital signs, pulmonary function test results, summary mental status test results, neurological examination results, electrocardiogram measurements, or blood serology tests (except for clinically insignificant increases in hematocrit and hematocrit values). platelet count), kidney, liver, pancreas, or heart damage associated with hydrogen inhalation.


Inhalation of 2.4% hydrogen does not appear to cause any clinically meaningful side effects in healthy adults. Although these data suggest that inhaled hydrogen may be well tolerated, future studies are needed to further assess safety. These data will form the basis for future intervention studies of hydrogen inhalation in injured states, including after cardiac arrest.


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