Diuretics are medicines that remove water from the body by increasing the amount of urine the kidneys produce. They are often known as "water tablets".

Types of Diuretics?

There are 3 types of diuretic medicines.

Each type works a little differently, but they all lower the amount of salt and water in your body, which helps to lower your blood pressure: Thiazides, loop diuretics and potassium-sparing diuretics (eg amiloride)

How  Diuretics Works?

Thiazides, loop diuretics and potassium-sparing diuretics all work on the kidneys.

The kidneys have a network of tubes that make urine by filtering the blood in two stages. In the first stage, the water, salt and the waste products such as urea are filtered out from the blood, leaving behind the red and white blood cells. But lots of nutrients and other essential substances also leave the blood at this stage.

In the second stage there is a backwards filter, where the kidneys re-absorb the nutrients and essential substances back into the blood. This leaves the waste products, plus some salt and water, in the kidneys. This waste leaves the kidneys as urine.

Heart failure makes the kidneys re-absorb more water and salt into the blood, and so produce less urine. This is the body's way of trying to compensate for the reduced pumping power of the heart, but it actually makes matters worse. There is a bigger volume of blood for the heart to pump, and so more work for it to do. Also the excess water in the blood tends to leak out into the lungs, which can lead to breathlessness. Heart failure can also make your ankles and feet swell up.

Diuretics reduce the amount of water and salt that is re-absorbed by your kidneys. So, more water and salt passes out with the waste products into your urine. This means that you make more urine. As a result of this loss of water from the blood, the overall volume of blood is reduced. This gives your heart less work to do and helps to reduce the pressure of blood in your arteries, which is what high blood pressure actually is.