Diuretics are medicines that cause the human body to produce more urine. Some of these medications, such as loop and thiazide diuretics, are categorized by the portion of the kidney which they affect. Other types of diuretic drugs, such as osmotic and potassium-sparing diuretics, are grouped by the ways in which they operate.
Loop diuretic drugs work by inhibiting the function of the area of the kidneys called Henle’s loop. This tiny loop is responsible for reabsorbing salt and water from urine. Due to the potency of loop diuretics, these drugs are generally reserved for the treatment of acute conditions, such as congestive heart failure and substantial hypertension.
Thiazide diuretics affect the distal convoluted tubule, a small portion of the kidneys near Henle’s loop. Although these drugs have fewer major side effects than loop diuretics, thiazides work in much the same way. Mild lethargy, skin irritation, and indigestion are possible with thiazide use. Blurry vision and headaches are also frequent complaints. Patients who experience severe nausea, vomiting, or unexplained muscle pain while using these diuretics are advised to contact their physicians as soon as possible.
The process by which osmotic diuretic drugs function is quite complicated. In essence, an osmotic drug siphons excess water into its structure. These water-laden molecules cannot be easily reabsorbed by the kidneys and are passed whole from the body. As osmotic diuretics do not affect the kidney directly, they are often used to increase urine output in patients with renal failure.
A major concern in the use of a diuretic drug is the possibility of a dangerous drop in potassium levels within the bloodstream. The resulting condition, termed hypokalemia, can lead to uncontrolled muscle spasms, abnormal heart rhythms, paralysis, and ultimately death. The likelihood of complications from hypokalemia is higher among patients with preexisting kidney or heart disease.
Potassium-sparing diuretic drugs, such as triamterene, may be prescribed with other classes of diuretic medications to reduce the risk of hypokalemia. The mechanism by which these drugs work varies, but the end result is potassium retention. These medicines are rarely used alone as their use can result in dangerously high potassium levels, or hyperkalemia. The primary and often only symptom of hyperkalemia is acute cardiac arrest.
Mild diuretics made from herbal ingredients may be purchased without a prescription. These over-the-counter products are frequently used for temporary weight loss. Like prescription diuretics, these products may cause hypokalemia.