How Do Diuretics Work?

Diuretics, sometimes called water pills, help rid your body of sodium and water. They work by making your kidneys excrete more sodium in urine. The sodium, in turn, takes water with it from your blood. That decreases the amount of fluid flowing through your blood vessels, which reduces pressure on the walls of your arteries.

are you taking the piss or something

Diuretics
People with chronic high blood pressure (hypertension) often take a class of drugs called diuretics to control their blood pressure. Diuretics reduce Na reabsorption from the lumen of the nephron. Water reabsorption is also reduced. Therefore, Na and water are lost in the urine, which increases urine flow. The decreased reabsorption of Na and water from the nephron reduces blood volume, thereby reducing blood pressure.