BACKGROUNDShoseiryuto, a Japanese herbal medicine, is used to treat asthma exacerbation; however, the effect of Shoseiryuto in a clinical setting is yet to be elucidated. We aimed to examine the effect of Shoseiryuto for inpatients with asthma exacerbation and the reduction in the total amount of intravenous steroids administered during hospitalization, in-hospital mortality, and length of hospital stay using a national inpatient database in Japan.METHODSUsing data from the Japanese Diagnosis Procedure Combination database (July 2010-March 2022), we identified patients aged ≥18 years who were admitted due to asthma exacerbation. We performed propensity score overlap weighting analyses to estimate the in-hospital outcomes between patients who received Shoseiryuto within 3 days of admission (Shoseiryuto group) and those who did not (control group). The outcomes measured were the dose of intravenous steroids administered, in-hospital mortality, and length of hospital stay for patients alive at discharge.RESULTSAmong 51,459 eligible patients, 131 received Shoseiryuto. In the propensity score overlap weighting analyses, the use of Shoseiryuto was significantly associated with reduced amount of intravenous steroid during hospitalization (67 mg versus 149 mg, 95% confidence interval [CI]: -68 to -92), but was not associated with reduced in-hospital mortality (1.9% versus 3.5%, 95% CI: -28 to 25) or length of hospital stay (17.3 days versus 18.3 days, 95% CI: -4.2 to 2.4).CONCLUSIONSThe use Shoseiryuto in inpatients with asthma exacerbation was significantly associated with reduced steroid use. Our results elucidated the potential role of Shoseiryuto in the treatment of asthma exacerbation.