BackgroundSTIs in older adults (adults aged 50 years and older) are on the rise due to variable levels of sex literacy and misperceived susceptibility to infections, among other factors. We systematically reviewed evidence on the effect of non-pharmacological interventions for the primary prevention of sexually transmitted infections (STIs) and high-risk sexual behaviour in older adults.MethodsWe searched EMBASE, MEDLINE, PSYCINFO, Global Health and the Cochrane Library from inception until March 9th, 2022. We included RCTs, cluster-randomised trials, quasi-RCTs, interrupted time series (ITS) and controlled and uncontrolled before-and-after studies of non-pharmacological primary prevention interventions (e.g. educational and behaviour change interventions) in older adults, reporting either qualitative or quantitative findings. At least two review authors independently assessed the eligibility of articles and extracted data on main characteristics, risk of bias and study findings. Narrative synthesis was performed.ResultsTen studies (two RCTs, seven quasi-experiment studies and one qualitative study) were found to be eligible for this review. These interventions were mainly information, education and communication activities (IECs) aimed at fostering participants’ knowledge on STIs and safer sex, mostly focused on HIV. Most studies used self-reported outcomes measuring knowledge and behaviour change related to HIV, STIs and safer sex. Studies generally reported an increase in STI/HIV knowledge. However, risk of bias was high or critical across all studies.ConclusionsLiterature on non-pharmacological interventions for older adults is sparse, particularly outside the US and for STIs other than HIV. There is evidence that IECs may improve short-term knowledge about STIs however, it is not clear this translates into long-term improvement or behaviour change as all studies included in this review had follow-up times of 3 months or less. More robust and higher-quality studies are needed in order to confirm the effectiveness of non-pharmacological primary prevention interventions for reducing STIs in the older adult population.