Det vides ikke med sikkerhed, hvordan denne mekanisme virker på stressinkontinens, men duloxetin menes at øge koncentrationen af 5- hydroxytryptamin og noradrenalin omkring de nerver, der kontrollerer urinrørets muskel, og derved forstærkes urinrørets lukning under opbevaring af urinen.
How duloxetine works in SUI is not clear but it is thought that, by increasing the levels of 5-hydroxytryptamine and noradrenaline at the level of the nerves that control the muscle of the urethra (the tube that leads from the bladder to outside), duloxetine causes a stronger closure of the urethra during urine storage.