Intravenous (IV) administration of paracetamol (APAP) is well-documented to cause severe hypotension, particularly in critically ill patients. We have previously shown that a metabolite of APAP – N-acetyl-p-benzoquinone imine (NAPQI) – is a potent vasodilator, but whether APAP can be metabolised to NAPQI in the vasculature is unknown. Here, we show that NAPQI can be generated by the human coronary endothelial cells (HCAECs) treated with APAP, by staining for APAP-adducts and showing a drop in cell viability and glutathione levels, similar to direct NAPQI treatment. We show that glutathione depletion following APAP treatment is caused the cytochrome p450 enzymes (CYPs) expressed in HCAECs by utilizing a blocker of the CYPs, ketoconazole. Furthermore, mass spectrometry analysis of HCAECs treated with 10 mM APAP for 24h shows upregulation of proteins involved in redox biology and the pentose phosphate pathway, as well as CYP20A1 and POR. Lastly, we show that myeloperoxidase can also metabolize APAP to NAPQI at physiologically relevant concentrations. Taken together, this study shows that APAP can be metabolized within the vasculature to the potent vasodilator NAPQI. We suggest that this is the mechanism by which critically ill patients can present with IV APAP-induced hypotension.