In ESCAPE-TRD (NCT04338321), esketamine nasal spray (NS) significantly increased the probability of remission at Week 8, and of being relapse-free through Week 32 after remission at Week 8, versus quetiapine extended release (XR) in patients with treatment resistant depression (TRD). Here, we explore the time course, burden and consequences of treatment emergent adverse events (TEAEs) in the phase IIIb ESCAPE‑TRD trial. Patients with TRD were randomised 1:1 to esketamine NS or quetiapine XR, dosed per label alongside an ongoing selective serotonin reuptake inhibitor/serotonin norepinephrine reuptake inhibitor. In this secondary publication, safety analyses (comprising patients who received ≥1 dose of study treatment) included incidence, severity and durations (Kaplan‑Meier method) of TEAEs, and subsequent dispositional changes. P values were not adjusted for multiple testing. 336 patients were randomised to esketamine NS and 340 to quetiapine XR; 334 and 336 received ≥1 dose of study treatment, respectively. TEAEs were significantly more common with esketamine NS than quetiapine XR (91.9 % versus 78.0 %; p < 0.001), but were typically mild/moderate and transient in nature: a greater proportion resolved on the same-day (92.0 % versus 12.1 %) and lead to treatment discontinuation in significantly fewer patients (4.2 % versus 11.0 %, respectively; p < 0.001). The proportion of days spent with TEAEs was significantly lower with esketamine NS than quetiapine XR (median: 11.9 % versus 21.3 %; p < 0.001). Although more frequent with esketamine NS, TEAEs were typically transient and mild, with discontinuation less likely versus quetiapine XR. Data were consistent with established safety profiles, with no new safety signals identified. Alongside greater efficacy, the demonstrably more favourable tolerability profile of esketamine NS versus quetiapine XR further supports its use for TRD.