Self-injurious thoughts and behaviours (SITBs) represent a critical public and mental health challenge. Adolescents are disproportionately at risk for engaging in SITBs. Intervening early and addressing pathogenic and proximal risk/vulnerability factors is of critical importance for this vulnerable population. Digital Single-Session Interventions (D-SSIs) offer a promising solution to unmet need for accessible, scalable and engaging care. This pilot study aims to evaluate the acceptability and feasibility of the interventions and clinical trial protocol for Programme LIFT (Little Interventions for Teens), a newly developed suite of D-SSIs targeting emotional regulation, self-criticism, rumination and hopelessness as key risk processes involved in the maintenance of SITBs.

We aim to recruit 216 Australian adolescents aged 15–19 years who have experienced SITBs in the past 2 months into an online, 2x2 factorial randomised controlled trial to pilot the acceptability and feasibility of the intervention protocol (D-SSI+28 days of skill practice) and trial procedures, and establish study retention. Random allocation procedures will be used to test factors that may affect adherence to the intervention protocol (primary feasibility outcome), by testing the effect of: (1) intervention assignment method (free choice vs clinician prescribed), and (2) a postintervention brief, supportive phone check-in at 7 days postcompletion of the D-SSI (phone call vs no call). Feasibility and acceptability will be assessed using online surveys at postintervention (T1) and 30 days follow-up (T3), along daily brief assessments of skill practice between T1 and T2 (T2). The trial and its protocol were developed and reported in accordance with the Standard Protocol Items for Interventional Trials checklist.

This study is approved by the University of New South Wales Human Research Ethics Committee (HREC#9032). Results will be published in an open access peer-reviewed journal, and key study findings will be shared with participants and stakeholders within 3 months after completion of the study.

ACTRN12625000963426.