ADHD medication use and risk of self-harm: a multinational self-controlled case series study

Conflicting evidence from observational studies and randomised trials has created uncertainty about the association between attention-deficit/hyperactivity disorder (ADHD) medication use and self-harm.

To assess the risk of incident self-harm associated with use of ADHD medication across multiple healthcare systems.

We conducted a multinational self-controlled case series study using a common data modelling approach to assess the risk of self-harm among individuals treated with ADHD medication across population-based databases from Hong Kong, New Zealand, South Korea, Taiwan and the United Kingdom. We included individuals who initiated ADHD medication and had a record of self-harm between 2001-2020. Incidence rate ratios (IRRs) for self-harm were calculated using conditional Poisson regression, comparing three risk periods of ADHD medication exposure (ie, the 90 days before medication initiation, the first 90 days of medication use and the subsequent treatment period) to non-exposure periods. Adjusted IRRs and 95% CIs were estimated for various risk periods. Estimates from each site were pooled using a random-effects model.

A total of 461 024 individuals with at least one prescription for ADHD medication were included, of whom 6847 had an incident self-harm event during the observation period. The risk was highest during the 90 days before medication initiation (pooled adjusted IRR: 2.58; 95% CI 2.12 to 3.13), followed by the first 90 days of medication use (pooled adjusted IRR: 1.78; 95% CI 1.23 to 2.57), and lowest in the subsequent treatment period (pooled adjusted IRR: 1.27; 95% CI 1.01 to 1.60). Results were consistent across included databases.

While the use of ADHD medication was associated with self-harm, the highest risk occurred during the unexposed period immediately before starting treatment. The consistent findings across various health systems do not support ADHD medications as the main driver of self-harm. Instead, the increased risk observed prior to treatment may be related to untreated ADHD features.

Although our findings provide reassurance that ADHD medications do not appear to be the main driver of the increased self-harm risk, the persistently elevated risk highlights the need for ongoing clinical monitoring and counselling before and during treatment.