If, on the other hand, the capillaries are very leaky, and tissues are therefore retaining both water and protein , then diuretics can do more harm than good.  They will cause the kidneys to remove fluid more rapidly from the blood while at the same time the protein in the tissue spaces will be drawing fluid from the blood into the tissues . The result can be dehydration of the blood . Over time, the use of diuretics can aggravate water retention of this type, as the body will learn to hold on to water in an attempt to avoid becoming dehydrated . 
Fluid retention in legs is a common condition caused by many factors, including illness, medications, and a high salt intake. Most cases of edema can be treated easily at home by improving your diet, exercising regularly, and taking herbal supplements to eliminate excess water from your body. A few simple changes can make a large difference in the overall quality of your life and reduce excess edema at the same time. Before making any drastic lifestyle changes or adding a lot of supplements to your diet, consult with a doctor to rule out dangerous conditions that might be causing your edema.