Suicidal ideation is a critical public health issue, often linked to functional limitations that hinder daily activities. However, the independent, interactive, and cumulative effects of specific types and quantities of functional limitations on suicidal ideation remain underexplored.

Data were analyzed from 12,263 U.S. adults in the National Health and Nutrition Examination Survey (NHANES, 2013–2018). Functional limitations were assessed across six domains: vision, hearing, cognitive, mobility, dressing/bathing, and errands. Multivariable logistic regression and interaction models were used to examine associations between functional limitations and suicidal ideation. Dose-response relationships were evaluated using restricted cubic spline regression.

Vision (OR = 1.77, 95 % CI = 1.00–3.13), cognitive (OR = 5.52, 95 % CI = 3.63–8.39), and errand limitations (OR = 1.75, 95 % CI = 1.09–2.79) were independently associated with suicidal ideation. A significant interaction effect was observed between hearing and cognitive limitations, with the co-occurrence amplifying suicidal ideation risk (OR = 5.80, 95 % CI = 3.84–8.78). Additionally, a dose-response relationship was found, with individuals experiencing ≥5 limitations having the highest risk.

Functional limitations, particularly cognitive and errand-related impairments, are strongly associated with suicidal ideation. Interaction effects and cumulative impacts underscore the need for integrated mental and physical healthcare approaches. Tailored interventions targeting specific limitations and addressing cumulative burdens may mitigate suicidal ideation in this vulnerable population.