Is suicidality contagious? The social transmission of suicidal thoughts and behaviors: A systematic review and meta-analysis

BACKGROUND: Suicide is a major public health problem and exposure to suicidal thoughts and behaviors (STBs) within the social network might increase individual risk. We conducted a systematic review and meta-analysis to quantitatively examine associations between exposure to STBs in friends, peers, and acquaintances, and own STBs. METHODS: We searched MEDLINE, PsycInfo, EMBASE, Scopus, CINAHL, and PubMed (inception-May 6, 2024, updated on November 5, 2025, and on February 22, 2026). We included observational studies reporting suicide-related outcomes for individuals exposed to STBs of friends, peers, or acquaintances, compared to non-exposed individuals. Two researchers extracted the data independently. Crude odds ratios were synthesized using a three-level random-effects meta-analysis, accounting for dependency in effect sizes. Subgroup analyses were conducted for several moderators. The study was pre-registered (PROSPERO, CRD42024532765). RESULTS: From 8046 records identified, we included 153 effect sizes from 59 primary studies across 1,055,483 individuals (50.8% male, 49.2% female). Exposure to STBs was associated with a 2.77-fold (95% CI 2.33-3.28) increase in odds of experiencing STBs. Associations persisted when specific exposures and outcomes were analyzed as moderators, except that exposure to STBs was not associated with suicide death. Furthermore, associations only held when exposure occurred from close friends (OR 3.22, 95% CI 2.73-3.79) or peers (OR 2.21, 95% CI 1.49-3.29), but not acquaintances. CONCLUSION: Our findings support the idea that suicidality is socially transmissible, while indicating that the closer the relationship, the greater the chance of social transmission of suicidality. This underlines the importance of looking beyond family relationships and considering close friends and suicidal peers in suicide prevention.