Both alteplase and tenecteplase can be used for stroke thrombolysis. This alert highlights action for all providers and issues where they have chosen to use tenecteplase. It identifies the need to differentiate clearly between the different dosages when using tenecteplase thrombolysis to treat acute ischaemic stroke or myocardial infarction. Serious errors, including fatalities, have occurred when there is confusion between thrombolytic medicine or dosages.