ObjectiveTo compare the effectiveness of hand hygiene using alcohol-based hand sanitiser to soap and water for preventing the transmission of acute respiratory infections (ARIs) and to assess the relationship between the dose of hand hygiene and the number of ARI, influenza-like illness (ILI) or influenza events.DesignSystematic review and meta-analysis.Data sourcesCochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, Cumulative Index of Nursing and Allied Health Literature (CINAHL) and trial registries were searched in April 2020.Inclusion criteriaWe included randomised controlled trials that compared a community-based hand hygiene intervention (soap and water, or sanitiser) with a control, or trials that compared sanitiser with soap and water, and measured outcomes of ARI, ILI or laboratory-confirmed influenza or related consequences.Data extraction and analysisTwo review authors independently screened the titles and abstracts for inclusion and extracted data.ResultsEighteen trials were included. When meta-analysed, three trials of soap and water versus control found a non-significant increase in ARI events (risk ratio (RR) 1.23, 95% CI 0.78 to 1.93); six trials of sanitiser versus control found a significant reduction in ARI events (RR 0.80, 95% CI 0.71 to 0.89). When hand hygiene dose was plotted against ARI relative risk, no clear dose–response relationship was observable. Four trials were head-to-head comparisons of sanitiser and soap and water but too heterogeneous to pool: two found a significantly greater reduction in the sanitiser group compared with the soap group and two found no significant difference between the intervention arms.ConclusionsAdequately performed hand hygiene, with either soap or sanitiser, reduces the risk of ARI virus transmission; however, direct and indirect evidence suggest sanitiser might be more effective in practice.