To identify the most frequently reported preferred terms （PTs） in the cases of rheumatoid arthritis （RA） patients treated with immunosuppressive biological drugs as suspected drugs, we analyzed the cases in the Japanese Adverse Drug Event Report （JADER） database. We found that pneumonia, interstitial lung disease, Pneumocystis jiroveci pneumonia （PCP), cellulitis, sepsis, and herpes zoster were the most frequently reported PTs. We obtained the reporting odds ratio （ROR） and the time to onset of these six PTs and compared them in the cases reported for each immunosuppressant as a suspected drug. We focused on RA treatment, including five tumor necrosis factor （TNF） antagonists （infliximab, etanercept, adalimumab, golimumab, and certolizumab pegol). For pneumonia, interstitial lung disease and sepsis, no specific correlation was observed for each immunosuppressant for RA. In the case of PCP, the highest ROR was observed in the patients treated with infliximab. The time to onset of PCP in the infliximab-treated patients （median, 0.19 yr） was significantly shorter than the onset time in the patients treated with tocilizumab, an interleukin-6 receptor blocker that is another type of drug for RA（0.32 yr, p<0.01, Mann-Whitney test). The onset time in the patients treated with golimumab （0.24 yr） was also significantly shorter than the onset time for tocilizumab（p<0.05), but the ROR was not as high. These results suggested a correlation between PCP and infliximab. In the cases of cellulitis and herpes zoster, a similar correlation was observed with tocilizumab and certolizumab pegol, respectively. We should consider these results when patients have a respiratory disorder or skin/subcutaneous tissue disorder.

To identify the most frequently reported preferred terms （PTs） in the cases of rheumatoid arthritis （RA） patients treated with immunosuppressive biological drugs as suspected drugs, we analyzed the cases in the Japanese Adverse Drug Event Report （JADER） database. We found that pneumonia, interstitial lung disease, Pneumocystis jiroveci pneumonia （PCP), cellulitis, sepsis, and herpes zoster were the most frequently reported PTs. We obtained the reporting odds ratio （ROR） and the time to onset of these six PTs and compared them in the cases reported for each immunosuppressant as a suspected drug. We focused on RA treatment, including five tumor necrosis factor （TNF） antagonists （infliximab, etanercept, adalimumab, golimumab, and certolizumab pegol). For pneumonia, interstitial lung disease and sepsis, no specific correlation was observed for each immunosuppressant for RA. In the case of PCP, the highest ROR was observed in the patients treated with infliximab. The time to onset of PCP in the infliximab-treated patients （median, 0.19 yr） was significantly shorter than the onset time in the patients treated with tocilizumab, an interleukin-6 receptor blocker that is another type of drug for RA（0.32 yr, p<0.01, Mann-Whitney test). The onset time in the patients treated with golimumab （0.24 yr） was also significantly shorter than the onset time for tocilizumab（p<0.05), but the ROR was not as high. These results suggested a correlation between PCP and infliximab. In the cases of cellulitis and herpes zoster, a similar correlation was observed with tocilizumab and certolizumab pegol, respectively. We should consider these results when patients have a respiratory disorder or skin/subcutaneous tissue disorder.