Using data from a post-marketing surveillance, this interim subgroup analysis investigated the safety of sarilumab in younger (<65 years) and older patients (≥65 and ≥75 years) with rheumatoid arthritis. During this interim analysis, patients who were treated with sarilumab in Japan were enrolled between June 2018-2021. Data collected by 12 January 2022 were analysed, with adverse drug events monitored over 52 weeks. Of 972 patients with available data, proportion of patients aged <65 years, ≥65 years and ≥75 years were 40.8%, 59.2% and 27.8%, respectively. Most patients (95.5%) received the standard 200 mg dose of sarilumab as the initial dose. Adverse drug reactions were reported in 24.6% of patients, with serious events accounting for 6.4% of cases. No malignancy and low incidences of adverse drug reactions of special interest were reported across all age groups (<65 years, 7.8%; ≥65 years, 8.2%; ≥75 years, 8.5%). When stratified by absolute neutrophil count above and below the lower limit of normal, there were no numerical differences in incidences of serious and non-serious infections between age groups. Regardless of age, sarilumab therapy was well tolerated by patients with rheumatoid arthritis, with no new safety signals reported in this study.