Water pills are pills which tell the kidneys to express sodium from the body, causing an excretion of excess water as well. They are more properly known as diuretics, and they are used to treat a wide variety of health conditions. Some people also take water pills for weight loss; this use is not advised, and it can actually be very dangerous. In addition to being potentially harmful when abused, water pills do not actively contribute to weight loss; they simply remove excess fluid from the body.

There are three main types of water pills. Loop diuretics interfere with the body's ability to absorb sodium, meaning that more water appears in the patient's urine, because water is normally pulled along with sodium. Thiazides work in a similar way, while potassium-sparing water pills are designed to help the body retain potassium while excreting sodium. Many water pills blend several several types; potassium-sparing diuretics are a common inclusions in a water pill since they ensure that the body's potassium levels remain healthy.

One common use of diuretics is as a blood pressure treatment. By triggering the kidneys to express extra water, the water pills lower overall blood volume, which can reduce blood pressure. Water pills are also used to treat people with conditions like edema, in which water is retained because the circulation of the lymphatic system is blocked. Diuretics are also sometimes used to help the body express toxins; the effectiveness varies, depending on the toxin.

Most prescription diuretics are formulated drugs, but some natural substances have diuretic properties as well. Coffee, for example, is a well known diuretic, and some water pills are actually derived from coffee. Parsley, juniper, goldenrod, and bearberry are all natural diuretics, and some of these substances are used in alternative health treatments. Such drugs should be used with care, as their dosages can be unpredictable since plants have varying amounts of chemical compounds depending on circumstances like their growing environment, available nutrients, and when they are harvested.

As anyone who has taken water pills for a medical condition knows, the pills can cause a small weight loss, because water is a heavy substance. However, this weight loss is not permanent, and it cannot be sustained. Unfortunately, some people take diuretics for the purpose of weight loss; this can cause low blood pressure, an imbalance of electrolytes, and other serious problems. Long term use of water pills is not generally recommended, and it is especially dangerous when undertaken without the supervision of a doctor. There are plenty of healthy ways to lose weight which will not put your body in danger and you can discuss these with a doctor or personal trainer.