Diuretics are medications that help the body eliminate sodium and water through the urine. They are commonly prescribed to treat high blood pressure, glaucoma, metabolic alkalosis, acute kidney failure, and fluid retention caused by conditions that affect the heart, kidneys, or liver. Diuretics can be used on their own or in combination with other medications.
There are several types of diuretics, including thiazide diuretics, loop diuretics, potassium-sparing diuretics, osmotic diuretics, and carbonic anhydrase inhibitors. Each type works in different ways and acts on specific areas of the kidneys.
A healthcare provider may recommend a specific type of diuretic based on the condition being treated. It is important to take these medications exactly as prescribed.
Main types
The main types of diuretics are:
1. Thiazide diuretics
Thiazide diuretics work by blocking sodium and chloride channels in the kidney’s renal tubules, preventing sodium from being reabsorbed and increasing its elimination in the urine. When sodium is excreted, it carries water with it, which helps reduce fluid retention and lower blood pressure. These diuretics also cause the elimination of chloride and potassium and help relax blood vessels, producing a moderate diuretic effect.
Generic/brand names: Common thiazide diuretics include indapamide (Lozol), hydrochlorothiazide (Microzide, HydroDIURIL, Oretic), chlorthalidone (Hygroton), and metolazone (Zaroxolyn).
Therapeutic indications: Thiazide diuretics are usually prescribed to lower blood pressure and to treat chronic swelling caused by congestive heart failure, liver cirrhosis, or kidney disease.
Most common side effects: Possible side effects include dizziness, headache, weakness, nausea, vomiting, abdominal cramps, diarrhea, constipation, gallbladder inflammation, pancreatitis, and changes in blood or skin health.
2. Loop diuretics
Loop diuretics act on a specific part of the kidney called the loop of Henle, increasing the elimination of sodium, water, and chloride, as well as smaller amounts of magnesium and calcium.
By preventing water reabsorption, these diuretics reduce fluid buildup in the body. They also have direct effects on blood flow, promoting vasodilation and reducing renal vascular resistance. Loop diuretics are strong, fast-acting medications with a short duration of effect.
Generic/brand names: Common loop diuretics include furosemide (Lasix), bumetanide (Bumex), torsemide (Demadex), and ethacrynic acid (Edecrin).
Therapeutic indications: Loop diuretics are used to manage acute pulmonary edema and other forms of swelling, as well as acute kidney failure, heart failure, and liver cirrhosis with fluid retention. They can also be used to treat acute hypercalcemia by increasing calcium excretion in the urine.
Most common side effects: Potential side effects include electrolyte imbalances, dehydration, low blood volume, increased blood creatinine and triglyceride levels, gout flare-ups, and frequent urination.
3. Potassium-sparing diuretics
Potassium-sparing diuretics increase the elimination of sodium and water while preventing potassium loss. Potassium is essential for maintaining normal heart rhythm and proper nerve and muscle function.
These diuretics have a milder effect and are usually prescribed for people who are at risk of developing low potassium levels or who are taking other medications that can lower potassium.
Generic/brand names: Common potassium-sparing diuretics include amiloride (available only in fixed-dose combinations, such as Moduretic), spironolactone (Aldactone), and eplerenone (Inspra).
Therapeutic indications: Because they have a weak diuretic effect, potassium-sparing diuretics are rarely used alone to treat swelling or high blood pressure. They are generally combined with thiazide or loop diuretics to increase their diuretic and blood pressure-lowering effects.
Most common side effects: Possible side effects include increased extracellular fluid volume, dehydration, and high sodium levels in the blood.
4. Osmotic diuretics
Osmotic diuretics increase osmotic pressure in the kidney’s tubules, preventing water reabsorption and increasing urine production. This helps decrease intracranial and intraocular pressure.
Generic/brand names: Mannitol (Osmitrol) is the most commonly used osmotic diuretic.
Therapeutic indications: Mannitol 20% is used to treat cerebral edema, acute glaucoma, acute kidney failure, and as a prep for certain eye surgeries.
Most common side effects: Possible side effects include nausea, vomiting, thirst, headache, dizziness, tremors, fever, rapid heartbeat, chest pain, high sodium levels, dehydration, blurred vision, hives, and high blood pressure.
5. Carbonic anhydrase inhibitor diuretics
Carbonic anhydrase inhibitor diuretics work by blocking the enzyme carbonic anhydrase, which helps regulate carbon dioxide transport and blood pH. When this enzyme is inhibited, the kidneys increase the elimination of bicarbonate and water through the urine.
Generic/brand names: Common examples include acetazolamide (Diamox) and methazolamide (Neptazane).
Therapeutic indications: Carbonic anhydrase inhibitors are prescribed for glaucoma, urinary alkalinization, metabolic alkalosis, and acute mountain sickness.
Most common side effects: Possible side effects include metabolic acidosis, increased extracellular fluid volume, low sodium levels, headache, drowsiness, nausea, vomiting, and dehydration.
Also recommended: 14 Natural Diuretic Teas for Fluid Retention tuasaude.com/en/natural-diureticsContraindications to use
Diuretics are not recommended during pregnancy or breastfeeding, or for people allergic to any of their ingredients. They should also be avoided in people with severe kidney problems, advanced liver failure, very low sodium or potassium levels, anuria (lack of urine production), severe heart failure, dehydration, and cirrhosis due to the risk of hepatic encephalopathy.