Describe how diuretics control edema?

Diuretics are a group of drugs given to help the body eliminate excess fluid through the kidneys in order to treat hypertension (high blood pressure), kidney and liver disorders, glaucoma, congestive heart failure (CHF), and idiopathic intracranial hypertension (pseudotumor cerebri), a condition characterized by increased fluid pressure within the blood vessels supplying the brain.

In addition to prescription diuretics, there are several types of diuretics available in over-the-counter formulations or commonplace beverages.
Purpose

Diuretics have several purposes in mainstream clinical medicine:

    To lower blood pressure in people with hypertension
    To lower fluid pressure inside the eyeball in patients with glaucoma
    To reduce increased cerebrospinal fluid pressure in idiopathic intracranial hypertension
    To reduce blood pressure and swelling during surgical procedures
    To reduce bloating and discomfort associated with fluid retention in the premenstrual phase of a woman’s monthly cycle

The simplest way to treat edema is to use diuretics, such as furosemide, which increase urine output. Increasing urine output decreases bodily water retention. Edema occurs when tiny blood vessels in your body (capillaries) leak fluid. The fluid builds up in surrounding tissues, leading to swelling. By reducing the level of water in the bloodstream, the fluid that escapes into surrounding tissues will seep back into the bloodstream due to osmosis.