Extended-release quetiapine overdose is associated with delayed onset of toxicity compared to immediate-release quetiapine overdose.

XR quetiapine overdoses without sedating co-ingestants were associated with a doubling of time to peak sedation and pulse, and had longer recovery from sedation. The absence of sedation or tachycardia 12 h post-overdose of XR quetiapine seems a reasonable timeframe to rule out significant poisoning.