BACKGROUND: SARS-CoV-2 and influenza virus are highly contagious respiratory viruses that continuously pose major threats to human and public health. The high frequency of viral mutations led to the emergence of resistant isolates and caused virus epidemics repeatedly, emphasizing the urgent need to develop new antivirals. Taurultam is a metabolite of taurolidine. Moreover, taurolidine has been shown to have potent antiviral activities against multiple viruses and to have antiviral effects through its metabolites. RESULTS: In this study, we sought to determine the antiviral activities of taurultam against SARS-CoV-2 and influenza virus in Vero-E6, Huh7, 293T-ACE2, and MDCK cell lines and mouse infection models. The results showed that taurultam exhibited potent antiviral activity against multiple SARS-CoV-2 variants, influenza A (H1N1, H3N2) virus and influenza B virus, in vitro. Moreover, in influenza A (H1N1) virus, influenza B virus and SARS-CoV-2 infection models, taurultam significantly reduced viral loads, increased survival, improved mouse body weight and lung injury. Surprisingly, taurultam treatment not only inhibited the influenza A virus and SARS-CoV-2, but also benefited for therapy of mixed infection of these two viruses in vitro, demonstrating the great antiviral potential of taurultam for the treatment of SARS-CoV-2 and influenza virus infections. CONCLUSIONS: Together, our findings identify taurultam as a new candidate for the treatment of SARS-CoV-2 and influenza virus infections, especially virus-induced lung pathology. CLINICAL TRIAL NUMBER: Not applicable.