Fluid retention, or edema, is an illness that affects the performance of heart as well as the work of liver and kidneys. It is generally treated by diuretics. The most effective are loop diuretics. Their name originates from the place they affect that is a part of the kidney tubules named as the loop of Henle. The latter are responsible for salt and water balance. The most frequently used diuretics are furosemide , torsemide, and butethamine.

These medications differ in the way of administration; depending on the condition they are taken orally or given intravenously. Sometimes for the better efficiency the diuretics can be given in complex with another agent provided a specific water pill alone fails to help. This refers to thiazide type diuretics, i.e. HydroDIURIL, or a resembling diuretic metolazone. As a result of such interaction a better response can be received and a condition is improved faster.

Potassium loss is infrequent in people taking diuretics and such a therapy can end up with depletion of body potassium. This condition refers to patients on therapy with loop and thiazide diuretics, as well as metolazone. It is strongly recommended to include into daily allowance of these people some potassium supplements or foods containing this element, i.e. bananas, orange juice, tomatoes, and potatoes. Sometimes it is useful to take a potassium-sparing diuretic which will not evoke the potassium loss. They are spironolactone, triamterene, amiloride, and acetazolamide.

Contrariwise, potassium supplements and foods are contraindicated to patients with kidney problems as kidneys themselves are tend to hold excess of potassium.