AimsThere are increasing concerns about harms related to suboptimal antipsychotic use. Here we describe recent population‐based trends in antipsychotic use and harms in Australia and identify population groups exhibiting patterns of use likely to contribute to these harms.MethodsUsing population‐based data from the Australian Pharmaceutical Benefits Scheme (2015‐2020), poisoning calls to the New South Wales (NSW) Poisons Information Centre (2015‐2020) and poisoning deaths in all coronial records (2005‐2018) in Australia, we measured trends in the prevalence of antipsychotic use and related deaths and poisonings. We applied latent class analyses to identify patterns of antipsychotic use that may contribute to harms.ResultsQuetiapine and olanzapine had the highest prevalence of use between 2015 and 2020. Noteworthy trends included increases of 9.1% and 30.8% in quetiapine use and poisonings, while olanzapine use decreased by 4.5% but poisonings increased by 32.7%. Quetiapine and olanzapine poisonings and related deaths had the highest rates of co‐ingestion of opioids, benzodiazepines and pregabalin compared to other antipsychotics. We identified six distinct population groups using antipsychotics: (i) ongoing high‐dose use with sedatives (8%), (ii) ongoing use (42%), (iii) ongoing use with analgesics and sedatives (11%), (iv) long‐term low‐dose use (9%), (v) sporadic use (20%) and (vi) sporadic use with analgesics (10%).ConclusionOngoing potentially suboptimal antipsychotic use and associated harms highlight the need to monitor such patterns of use, for example through prescription monitoring systems.