BackgroundRoutine blood sampling can be conducted using venepuncture, inserting a new peripheral intravenous cannula (PIVC), or utilising an existing one. The practice of blood sampling from a cannula requires handling and movement of the cannula bung. It is discouraged due to safety concerns linked to increased risk of phlebitis, infection, or reduced dwell time. AimTo assess cannula dwell time, the prevalence of phlebitis, and bloodstream infection when using a peripheral intravenous cannula compared with venepuncture for blood sampling. DesignA randomised controlled study. Reporting followed CONSORT recommendations. MethodAdult patients admitted to the emergency department whose health condition required a blood sample to be drawn and insertion of a PIVC were screened for eligibility between May and July 2022. Participants were randomised to either have blood sampled by venepuncture as the control or drawn through the peripheral intravenous cannula as the intervention. Follow-up occurred on day three post emergency department presentation. ResultsOne hundred and five participants were randomised of whom 50 had blood sampled by venepuncture and 55 through the peripheral intravenous cannula. No difference was observed in cannula dwell time, prevalence of phlebitis or signs of bloodstream infection. ConclusionThis study showed peripheral intravenous cannula outcomes were no different when the peripheral intravenous cannula was used to sample blood compared with participants whose blood was sampled by venepuncture.