BackgroundAlthough tranexamic acid is widely used in patients with haemoptysis, whether it improves mortality has not been well investigated. The aim of this study was to evaluate the effect of tranexamic acid on in-hospital mortality among patients with haemoptysis.MethodsThis was a retrospective study using data from the Japanese Diagnosis Procedure Combination inpatient database. We identified all cases of emergency admission due to haemoptysis from July 2010 to March 2017. Patients were divided into two groups: a control group, and a tranexamic acid group (those who received tranexamic acid on the day of admission). The primary outcome was in-hospital mortality, with secondary outcomes of hospital stay length and total healthcare cost. The data were evaluated using a propensity score matching analysis.ResultsAmong 28,539 included patients, 17,049 patients received tranexamic acid and 11,490 patients did not. Propensity score analysis generated 9933 matched pairs. Compared to the control group, patients in the tranexamic acid group had significantly lower in-hospital mortality (11.5% vs. 9.0%; risk difference, − 2.5%; 95% confidence interval (CI), − 3.5 to − 1.6%), shorter hospital stays (18 ± 24 days vs. 16 ± 18 days; risk difference, − 2.4 days; 95% CI, − 3.1 to − 1.8 days), and lower total healthcare costs ($7573 ± 10,085 vs. $6757 ± 9127; risk difference, $− 816; 95% CI, $− 1109 to − 523).ConclusionsTranexamic acid may reduce in-hospital mortality among patients with haemoptysis requiring emergency admission.