An earlier study by our group of the shorter-acting PDE-5 inhibitor, sildenafil, revealed that it causes orthostatic hypotension, tachycardia, and dizziness after administration in the SCI population, particularly in those with tetraplegia, and suggested that caution should be used when prescribing sildenafil to persons with SCIs, as blood pressure can drop significantly [27]. Here, PDE5A is linked to orthostatic hypotension.