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Drug class
Other namesWater pill, fluid pill[1]
Clinical data
UsesFluid overload, high blood pressure[2]
Common typesLoop diuretics, thiazide diuretics, potassium-sparing diuretics, carbonic anhydrase inhibitors[2]
External links
Drugs.comDrug Classes

Diuretics, also called water tablets, are a class of medicine used to treat fluid overload and high blood pressure.[2] They can be given by mouth or injection.[2] Types vary according to how and where in the part of the kidney they work.[3] They include loop diuretics, thiazide diuretics, potassium-sparing diuretics and carbonic anhydrase inhibitors.[4] Whilst taking a diuretic, monitoring includes regular blood tests, and checks on blood pressure, weight and urine.[4]

Side effects include dehydration, lowering blood pressure too much, a low potassium or high potassium, and changes in blood calcium, sugar and magnesium levels.[1] Common side effects may present as constipation, dry mouth, dizziness, gout, headache, upset stomach, fatigue and muscle cramps.[1] Severe side effects such as Stevens-Johnson syndrome or erythema multiforme may occur in a person with a sulphonamide allergy.[1] A loop diuretic in a person with liver failure might cause neurological symptoms, and in a person with kidney problems might result in ringing in ears or hearing loss.[1] They work by acting on the kidney to remove extra fluid by increasing the amount of urine produced.[5]

Using substances to reduce fluids in the body can be traced to ancient times.[6] Injection forms and tablets forms of bumetanide and furosemide are inexpensive, but in liquid form costs considerably more.[7] Other inexpensive generic diuretics include indapamide, bendroflumethiazide and chlortalidone.[7] In sports, diuretics are banned by the World Anti-Doping Agency.[8]

Medical uses

In medicine, diuretics are used to treat heart failure, liver cirrhosis, hypertension, influenza, water poisoning, and certain kidney diseases. Some diuretics, such as acetazolamide, help to make the urine more alkaline and are helpful in increasing excretion of substances such as aspirin in cases of overdose or poisoning. Diuretics are sometimes abused by people with an eating disorder, especially people with bulimia nervosa, with the goal of losing weight.

The antihypertensive actions of some diuretics (thiazides and loop diuretics in particular) are independent of their diuretic effect.[9][10] That is, the reduction in blood pressure is not due to decreased blood volume resulting from increased urine production, but occurs through other mechanisms and at lower doses than that required to produce diuresis. Indapamide was specifically designed with this in mind, and has a larger therapeutic window for hypertension (without pronounced diuresis) than most other diuretics.

Alternatively, an antidiuretic, such as vasopressin (antidiuretic hormone), is an agent or drug which reduces the excretion of water in urine.


High ceiling/loop diuretic

High ceiling diuretics may cause a substantial diuresis – up to 25%[5] of the filtered load of NaCl (salt) and water. This is large in comparison to normal renal sodium reabsorption which leaves only about 0.4% of filtered sodium in the urine. Loop diuretics have this ability, and are therefore often synonymous with high ceiling diuretics. Loop diuretics, such as furosemide, inhibit the body's ability to reabsorb sodium at the ascending loop in the nephron, which leads to an excretion of water in the urine, whereas water normally follows sodium back into the extracellular fluid. Other examples of high ceiling loop diuretics include ethacrynic acid and torasemide.


Thiazide-type diuretics such as hydrochlorothiazide act on the distal convoluted tubule and inhibit the sodium-chloride symporter leading to a retention of water in the urine, as water normally follows penetrating solutes. Frequent urination is due to the increased loss of water that has not been retained from the body as a result of a concomitant relationship with sodium loss from the convoluted tubule. The short-term anti-hypertensive action is based on the fact that thiazides decrease preload, decreasing blood pressure. On the other hand, the long-term effect is due to an unknown vasodilator effect that decreases blood pressure by decreasing resistance.[11]

Carbonic anhydrase inhibitors

Carbonic anhydrase inhibitors inhibit the enzyme carbonic anhydrase which is found in the proximal convoluted tubule. This results in several effects including bicarbonate accumulation in the urine and decreased sodium absorption. Drugs in this class include acetazolamide and methazolamide.

Potassium-sparing diuretics

These are diuretics which do not promote the secretion of potassium into the urine; thus, potassium is retained and not lost as much as with other diuretics. The term "potassium-sparing" refers to an effect rather than a mechanism or location; nonetheless, the term almost always refers to two specific classes that have their effect at similar locations:

Calcium-sparing diuretics

The term "calcium-sparing diuretic" is sometimes used to identify agents that result in a relatively low rate of excretion of calcium.[12]

The reduced concentration of calcium in the urine can lead to an increased rate of calcium in serum. The sparing effect on calcium can be beneficial in hypocalcemia, or unwanted in hypercalcemia.

The thiazides and potassium-sparing diuretics are considered to be calcium-sparing diuretics.[13]

  • The thiazides cause a net decrease in calcium lost in urine.[14]
  • The potassium-sparing diuretics cause a net increase in calcium lost in urine, but the increase is much smaller than the increase associated with other diuretic classes.[14]

By contrast, loop diuretics promote a significant increase in calcium excretion.[15] This can increase risk of reduced bone density.[16]

Osmotic diuretics

Osmotic diuretics (e.g. mannitol) are substances that increase osmolarity but have limited tubular epithelial cell permeability. They work primarily by expanding extracellular fluid and plasma volume, therefore increasing blood flow to the kidney, particularly the peritubular capillaries. This reduces medullary osmolality and thus impairs the concentration of urine in the loop of Henle (which usually uses the high osmotic and solute gradient to transport solutes and water). Furthermore, the limited tubular epithelial cell permeability increases osmolality and thus water retention in the filtrate.[17]

It was previously believed that the primary mechanism of osmotic diuretics such as mannitol is that they are filtered in the glomerulus, but cannot be reabsorbed. Thus their presence leads to an increase in the osmolarity of the filtrate and to maintain osmotic balance, water is retained in the urine.

Glucose, like mannitol, is a sugar that can behave as an osmotic diuretic. Unlike mannitol, glucose is commonly found in the blood. However, in certain conditions, such as diabetes mellitus, the concentration of glucose in the blood (hyperglycemia) exceeds the maximum reabsorption capacity of the kidney. When this happens, glucose remains in the filtrate, leading to the osmotic retention of water in the urine. Glucosuria causes a loss of hypotonic water and Na+, leading to a hypertonic state with signs of volume depletion, such as dry mucosa, hypotension, tachycardia, and decreased turgor of the skin. Use of some drugs, especially stimulants, may also increase blood glucose and thus increase urination.[citation needed].

Low ceiling diuretics

The term "low ceiling diuretic" is used to indicate a diuretic has a rapidly flattening dose effect curve (in contrast to "high ceiling", where the relationship is close to linear). Certain classes of diuretic are in this category, such as the thiazides.[18]

Mechanism of action

Diuretics are tools of considerable therapeutic importance. First, they effectively reduce blood pressure. Loop and thiazide diuretics are secreted from the proximal tubule via the organic anion transporter-1 and exert their diuretic action by binding to the Na(+)-K(+)-2Cl(-) co-transporter type 2 in the thick ascending limb and the Na(+)-Cl(-) co-transporter in the distal convoluted tubule, respectively.[19] Classification of common diuretics and their mechanisms of action.

Examples Mechanism Location (numbered in distance along nephron)
ethanol (alcohol), water Inhibits vasopressin secretion
Acidifying salts calcium chloride, ammonium chloride 1.
Arginine vasopressin
receptor 2
amphotericin B, lithium[20][21] Inhibits vasopressin's action 5. collecting duct
Selective vasopressin V2 antagonist (sometimes called aquaretics) tolvaptan,[22] conivaptan Competitive vasopressin antagonism leads to decreased number of aquaporin channels in the apical membrane of the renal collecting ducts in kidneys, causing decreased water reabsorption. This causes an increase in renal free water excretion (aquaresis), an increase in serum sodium concentration, a decrease in urine osmolality, and an increase in urine output.[23] 5. collecting duct
Na-H exchanger antagonists dopamine[24] Promotes Na+ excretion 2. proximal tubule[24]
Carbonic anhydrase inhibitors acetazolamide,[24] dorzolamide Inhibits H+ secretion, resultant promotion of Na+ and K+ excretion 2. proximal tubule
Loop diuretics bumetanide,[24] ethacrynic acid,[24] furosemide,[24] torsemide Inhibits the Na-K-2Cl symporter 3. medullary thick ascending limb
Osmotic diuretics glucose (especially in uncontrolled diabetes), mannitol Promotes osmotic diuresis 2. proximal tubule, descending limb
Potassium-sparing diuretics amiloride, spironolactone, eplerenone, triamterene, potassium canrenoate. Inhibition of Na+/K+ exchanger: Spironolactone inhibits aldosterone action, Amiloride inhibits epithelial sodium channels[24] 5. cortical collecting ducts
Thiazides bendroflumethiazide, hydrochlorothiazide Inhibits reabsorption by Na+/Cl symporter 4. distal convoluted tubules
Xanthines caffeine, theophylline, theobromine Inhibits reabsorption of Na+, increase glomerular filtration rate 1. tubules

Chemically, diuretics are a diverse group of compounds that either stimulate or inhibit various hormones that naturally occur in the body to regulate urine production by the kidneys.

As a diuretic is any substance that promotes the production of urine, aquaretics that cause the excretion of free water are a sub-class. This includes all the hypotonic aqueous preparations, including pure water, black and green teas, and teas prepared from herbal medications. Any given herbal medication will include a vast range of plant-derived compounds, some of which will be active drugs that may also have independent diuretic action.

Side effects

The main side effects of diuretics are hypovolemia, hypokalemia, hyperkalemia, hyponatremia, metabolic alkalosis, metabolic acidosis, and hyperuricemia.[24]

Severe side effects include Stevens-Johnson syndrome or erythema multiforme in a person with a sulphonamide allergy who has taken a sulphonamide-containing diuretic.[1] A loop diuretic in a person with liver failure might cause neurological symptoms, and in a person with kidney problems might result in ringing in ears or hearing loss.[1]

Adverse effect Diuretics Symptoms
metabolic alkalosis
metabolic acidosis


Using substances to induce diuresis can be traced to ancient times.[6] Several plants were noted to have diuretic properties in De Materia Medica. Arabic medicine expanded the list and it was continued during the renaissance. Foxglove appears in the 17th century London Pharmacopoeia and its diuretic properties were published in 1785 by British physician William Withering. By the Second World War, there were four drugs generally accepted as effective for reducing fluid overload; caffeine, digitalis, mercury and acidifying agents.[6]

Society and culture

A common application of diuretics is for the purposes of invalidating drug tests.[25] Diuretics increase the urine volume and dilute doping agents and their metabolites. Another use is to rapidly lose weight to meet a weight category in sports like boxing and wrestling.[8]

Diuretics are banned by the World Anti-Doping Agency.[8]

See also


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "List of Common Diuretics + Uses & Side Effects". Drugs.com. Archived from the original on 12 November 2021. Retrieved 11 November 2021.
  2. 2.0 2.1 2.2 2.3 "2. Cardiovascular system". British National Formulary (BNF) (82 ed.). London: BMJ Group and the Pharmaceutical Press. September 2021 – March 2022. pp. 242–249. ISBN 978-0-85711-413-6.{{cite book}}: CS1 maint: date format (link)
  3. Sam, Ramin; Pearce, David (2020). "15. Diuretic agents". In Katzung, Bertram G.; Trevor, Anthony J. (eds.). Basic and Clinical Pharmacology (15th ed.). New York: McGraw-Hill. pp. 262–284. ISBN 978-1-260-45231-0. Archived from the original on 2021-10-10. Retrieved 2021-11-11.
  4. 4.0 4.1 Arumugham, Vijay B.; Shahin, Mohamed H. (2021). "Therapeutic Uses Of Diuretic Agents". StatPearls. StatPearls Publishing. PMID 32491770. Archived from the original on 2021-11-14. Retrieved 2021-11-12.
  5. 5.0 5.1 Ritter, James M.; Flower, Rod; Henderson, Graeme; Loke, Yoon Kong; Rang, Humphrey P. (2020). "30. The kidney and urinary system". Rang & Dale's Pharmacology (9th ed.). Elsevier. pp. 388–392. ISBN 978-0-7020-7448-6. Archived from the original on 2021-08-28. Retrieved 2021-11-12.
  6. 6.0 6.1 6.2 Eknoyan, Garabed (1997). "1. A history of diuretics". In Seldin, Donald W.; Giebisch, Gerhard H. (eds.). Diuretic Agents: Clinical Physiology and Pharmacology. San Diego: Academic Press. pp. 3–30. ISBN 0-12-635690-4. Archived from the original on 2021-11-13. Retrieved 2021-11-12.
  7. 7.0 7.1 Hitchings, Andrew; Lonsdale, Dagan; Burrage, Daniel; Baker, Emma (2019). The Top 100 Drugs: Clinical Pharmacology and Practical Prescribing (2nd ed.). Elsevier. pp. 120–123. ISBN 978-0-7020-7442-4. Archived from the original on 2021-05-22. Retrieved 2021-11-09.
  8. 8.0 8.1 8.2 Cadwallader AB, de la Torre X, Tieri A, Botrè F (September 2010). "The abuse of diuretics as performance-enhancing drugs and masking agents in sport doping: pharmacology, toxicology and analysis". British Journal of Pharmacology. 161 (1): 1–16. doi:10.1111/j.1476-5381.2010.00789.x. PMC 2962812. PMID 20718736.
  9. Shah, Shaukat; Khatri, Ibrahim; Freis, Edward D. (1978). "Mechanism of antihypertensive effect of thiazide diuretics". American Heart Journal. 95 (5): 611–618. doi:10.1016/0002-8703(78)90303-4. PMID 637001.
  10. Ballew JR, Fink GD (September 2001). "Characterization of the antihypertensive effect of a thiazide diuretic in angiotensin II-induced hypertension". Journal of Hypertension. 19 (9): 1601–6. doi:10.1097/00004872-200109000-00012. PMID 11564980. S2CID 8531997.
  11. Julio D. Duarte; Rhonda M. Cooper-DeHoff (April 1, 2011). "Mechanisms for blood pressure lowering and metabolic effects of thiazide and thiazide-like diuretics". Expert Review of Cardiovascular Therapy. 8 (6): 793–802. doi:10.1586/erc.10.27. PMC 2904515. PMID 20528637.
  12. Shankaran S, Liang KC, Ilagan N, Fleischmann L (April 1995). "Mineral excretion following furosemide compared with bumetanide therapy in premature infants". Pediatr. Nephrol. 9 (2): 159–62. doi:10.1007/BF00860731. PMID 7794709. S2CID 21202583.
  13. Bakhireva LN, Barrett-Connor E, Kritz-Silverstein D, Morton DJ (June 2004). "Modifiable predictors of bone loss in older men: a prospective study". Am J Prev Med. 26 (5): 436–42. doi:10.1016/j.amepre.2004.02.013. PMID 15165661.
  14. 14.0 14.1 Champe, Pamela C.; Richard Hubbard Howland; Mary Julia Mycek; Harvey, Richard P. (2006). Pharmacology. Philadelphia: Lippincott William & Wilkins. p. 269. ISBN 978-0-7817-4118-7.
  15. Rejnmark L, Vestergaard P, Pedersen AR, Heickendorff L, Andreasen F, Mosekilde L (January 2003). "Dose-effect relations of loop- and thiazide-diuretics on calcium homeostasis: a randomized, double-blinded Latin-square multiple cross-over study in postmenopausal osteopenic women". Eur. J. Clin. Invest. 33 (1): 41–50. doi:10.1046/j.1365-2362.2003.01103.x. PMID 12492451. S2CID 36030615.
  16. Rejnmark L, Vestergaard P, Heickendorff L, Andreasen F, Mosekilde L (January 2006). "Loop diuretics increase bone turnover and decrease BMD in osteopenic postmenopausal women: results from a randomized controlled study with bumetanide". J. Bone Miner. Res. 21 (1): 163–70. doi:10.1359/JBMR.051003. PMID 16355285. S2CID 41216704.
  17. Du, Xiaoping. Diuretics Archived April 7, 2006, at the Wayback Machine. Department of Pharmacology, University of Illinois at Chicago.
  18. Mutschler, Ernst (1995). Drug actions: basic principles and therapeutic aspects. Stuttgart, German: Medpharm Scientific Pub. p. 460. ISBN 978-0-8493-7774-7.
  19. Ali SS, Sharma PK, Garg VK, Singh AK, Mondal SC (Apr 2012). "The target-specific transporter and current status of diuretics as antihypertensive". Fundam Clin Pharmacol. 26 (2): 175–9. doi:10.1111/j.1472-8206.2011.01012.x. PMID 22145583. S2CID 43171023.
  20. Ajay K. Singh; Gordon H. Williams (12 January 2009). Textbook of Nephro-Endocrinology. Academic Press. pp. 250–251. ISBN 978-0-08-092046-7. Archived from the original on 29 April 2021. Retrieved 11 August 2021.
  21. L. Kovács; B. Lichardus (6 December 2012). Vasopressin: Disturbed Secretion and Its Effects. Springer Science & Business Media. pp. 179–180. ISBN 978-94-009-0449-1. Archived from the original on 28 April 2021. Retrieved 11 August 2021.
  22. Schrier, Robert W.; Gross, Peter; Gheorghiade, Mihai; Berl, Tomas; Verbalis, Joseph G.; Czerwiec, Frank S.; Orlandi, Cesare (2006-11-16). "Tolvaptan, a Selective Oral Vasopressin V2-Receptor Antagonist, for Hyponatremia". New England Journal of Medicine. 355 (20): 2099–2112. doi:10.1056/NEJMoa065181. hdl:2437/157922. ISSN 0028-4793. PMID 17105757.
  23. Reilly, Timothy; Chavez, Benjamin (2009-10-01). "Tolvaptan (samsca) for hyponatremia: is it worth its salt?". Pharmacy and Therapeutics. 34 (10): 543–547. PMC 2799145.
  24. 24.00 24.01 24.02 24.03 24.04 24.05 24.06 24.07 24.08 24.09 24.10 24.11 24.12 24.13 24.14 24.15 24.16 24.17 24.18 24.19 24.20 24.21 24.22 24.23 24.24 24.25 24.26 24.27 24.28 24.29 24.30 24.31 24.32 24.33 24.34 24.35 24.36 24.37 24.38 24.39 24.40 24.41 24.42 24.43 Boron, Walter F. (2004). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. p. 875. ISBN 978-1-4160-2328-9.
  25. Boyd, Jessica M.; Sadrzadeh, S. M. Hossein (2019). "14. Limitations of immunoassays for screening of drugs of abuse in urine: issues of false positive and false negative results". In Dasgupta, Amitava; Sepulveda, Jorge L. (eds.). Accurate Results in the Clinical Laboratory: A Guide to Error Detection and Correction (2nd ed.). Amsterdam: Elsevier. p. 234. ISBN 978-0-12-813776-5. Archived from the original on 2021-11-14. Retrieved 2021-11-12.

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