ObjectiveTo conduct a systematic review of the effectiveness and safety of pharmacological treatments for adult-onset Still's disease (AOSD).MethodsSix databases, two trial registries and conference abstracts were searched from 2012 to February 2023 for studies of pharmacological interventions in people with AOSD. Outcomes were rates of remission and response, discontinuation of concurrent treatments, complications of AOSD and treatment-related adverse events. Risk of bias was assessed with the Cochrane RoB tool and the Joanna Briggs Institute tool for case series.Results44 studies evaluated treatments, including non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and biologic DMARDs (bDMARDs). For bDMARDS, tocilizumab, anakinra and canakinumab had the most available data. Although three randomised controlled trials did not show statistically significant benefits of bDMARDs, meta-analyses showed high rates of complete remission and corticosteroid discontinuation. Complete remission was 80% (95% confidence interval (CI): 59-92%, I2: 36%), 73% (95% CI: 58-84%, I2: 66%), and 77% (95% CI: 29-97%, I2: 82%) and corticosteroid discontinuation was 57% (95% CI: 29-81%, I2: 66%), 47% (95% CI: 18-78%, I2: 79%), and 34% (95% CI: 6-81%, I2: 59%), respectively, for tocilizumab, anakinra and canakinumab. Studies with a higher proportion of patients previously treated with bDMARDs showed a trend towards lower rates of corticosteroid discontinuation (p=0.05). The analyses had high clinical heterogeneity, largely because treatments were prescribed as different lines of therapy.ConclusionEvidence supports tocilizumab, anakinra and canakinumab therapy for AOSD. However, the magnitude of effect and comparative effectiveness of treatments is uncertain.