Randomized double-blind placebo-controlled trial of hydrogen inhalation for Parkinson’s disease: a pilot study
Yoritaka A et al. · Neurol Sci. 2021;42(11):4767–4770.
Study at a glance
Human
Japanese adults with Parkinson’s disease receiving levodopa
Mixed air containing H₂ at 2,000 mL/min for 1 hour twice daily · 6.5 ± 0.1% H₂ in the 2 L/min source mixture.
1 hour twice daily for 16 weeks
No significant between-group difference was found in total MDS-UPDRS or its parts at week 16. No adverse events were reported.
Very small pilot; five of 20 participants were excluded for insufficient inhalation time, leaving an unbalanced per-protocol sample. Several authors disclosed pharmaceutical relationships and departmental commercial endowments.
What kind of evidence is this?
Human
Randomized double-blind placebo-controlled parallel pilot trial
Parkinson’s disease
Other forms
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
Japanese adults with Parkinson’s disease receiving levodopa
20 enrolled; 15 included in the per-protocol analysis: H₂ n=7 and placebo n=8
1 hour twice daily for 16 weeks
Mixed air containing H₂ at 2,000 mL/min for 1 hour twice daily
H₂ diluted in air — H₂ was the active added gas, not Brown’s gas.
6.5 ± 0.1% H₂ in the 2 L/min source mixture.
Placebo air at 2,000 mL/min from an indistinguishable modified machine
Outcomes and reported result
MDS-UPDRS, PDQ-39, oxidative-stress measures, adherence and adverse events
No significant between-group difference was found in total MDS-UPDRS or its parts at week 16. No adverse events were reported.
The complete open-access article was checked for gas concentration, flow, allocation, adherence, all reported outcome tables, adverse events and competing interests.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Very small pilot; five of 20 participants were excluded for insufficient inhalation time, leaving an unbalanced per-protocol sample. Several authors disclosed pharmaceutical relationships and departmental commercial endowments.
Adults with Parkinson’s disease receiving levodopa under the reported home-inhalation protocol.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 34319514 · DOI: 10.1007/s10072-021-05489-4
Open-access full text is available through PMC.
Open-access PMC full text, PubMed record and UMIN registration.
10 August 2026
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