why does a medication that increases the amount of urine reduce blood pressure?

Answer 1

It's all about the amount of fluid in your body- if it makes you pee, that reduces how much fluid is in your body... including in your blood stream and in the surounding tissues. That reduces how much pressure your blood veins are under... from inside and outside.

Answer 2

Diuretics

Diuretics are among the oldest known medications for treating hypertension. They work in the tiny tubes (tubules) of the kidneys to remove salt from the body. Water (fluid) also may be removed along with the salt. Diuretics may be used as single drug treatment (monotherapy) for hypertension. More frequently, however, low doses of diuretics are used in combination with other anti-hypertensive medications to enhance the effect of the other medications.

The diuretic hydrochlorothiazide (Hydrodiuril) works in the far end (distal) part of the kidney tubules to increase the amount of salt that is removed from the body in the urine. In a low dose of 12.5 to 25 mg per day, this diuretic may improve the blood pressure-lowering effects of other anti-hypertensive drugs. The idea is to treat the hypertension without causing the adverse effects that are sometimes seen with the higher doses of hydrochlorothiazide. These side effects include potassium depletion and elevated levels of triglyceride (fat), uric acid, and glucose (sugar) in the blood.

Occasionally, when salt retention causing accumulation of water and swelling (edema) is a major problem, the more potent, so-called, loop diuretics may be used in combination with other anti-hypertensive medications. (The loop diuretics are so called because they work in the loop segment of the kidney tubules to eliminate salt.) The most commonly used diuretics to treat hypertension include hydrochlorothiazide (Hydrodiuril), the loop diuretics furosemide (Lasix) and torsemide (Demadex), the combination of triamterene and hydrochlorothiazide (Dyazide), and metolazone (Zaroxolyn). For those individuals who are allergic to sulfa drugs, ethacrynic acid, a loop diuretic, is a good option. Note that diuretics probably should not be used in pregnant women. (See the section above on pregnancy.)

Answer 3

Both of the previous answers were right. The excess fluid causes pressure on your veins and your heart has to pump harder than necessary. When you take the diuretics (lasix, dyazide, etc.) you remove that excess fluid, your heart doesn't have to work so hard. I have taken lasix and dyazide for 10 years for my high blood pressure. If I miss a dose, I'm swollen by the end of the day.