Key Points
  • Monitor fluid status, electrolytes and renal function before and after starting a diuretic, and at each re-prescription or every three to six months
  • Devise a patient management plan which includes more frequent monitoring during episodes of acute illness and periods of hot weather
  • Consider a medicines review for patients at high risk of diuretic-induced adverse effects, or if you have any concerns about their medicines use
  • Consider that renal impairment or symptomatic hypotension from diuretic use may impact the optimal use of other medicines that reduce morbidity and mortality

Diuretics: reducing harm

Diuretics are a valuable class of medicines commonly used in the treatment of hypertension and heart failure.1 However, they are often overused.2

Older people are particularly vulnerable to their adverse effects, which commonly include fluid and electrolyte disturbances, renal impairment and metabolic abnormalities including hyperglycaemia and hyperlipidaemia.1, 3-7 Diuretics can also cause dermatitis3, urinary urgency2 and secondary gout in older people.7

Most diuretic-related adverse effects can be avoided or minimised with appropriate use, by closely monitoring patients and by adjusting the dose of the diuretic as needed.8

Diuretic infographic tick

Monitor fluid status, electrolytes and renal function

Most diuretic-induced adverse effects are dose-related and can be minimised or avoided by selecting the lowest dose necessary for effective blood pressure or volume control, close monitoring (see Table 1) and adjusting the dose of the diuretic as needed.3, 8, 10, 11 As a general guide, once the patient and treatment is stable, check fluid status, electrolytes and renal function at each re-prescription, or once every three to six months. Monitor more frequently if your patient becomes acutely unwell or treatments change.12

Table 1

Table 1. Suggestions for monitoring patients using diuretics


Check before starting

Check after starting or increasing the dose



Loop diuretics:

  • furosemide (also called frusemide)
  • *bumetanide
  • Fluid status
  • **Serum biochemistry12
  • Check that the patient is not using a thiazide diuretic (see Table 2)
  • Fluid status
  • Serum biochemistry12, 13
  • 1–2 weeks (or more frequently in high risk patients) after starting or increasing the dose
  • Then 3–6 monthly or more often if clinically needed2, 8, 12, 13

Aldosterone antagonists (also called mineralocorticoid receptor antagonists)

  • spironolactone
  • eplerenone

Other diuretics:

  • amiloride (potassium sparing diuretic)
  • Serum biochemistry
  • Blood pressure12
  • Serum biochemistry
  • Blood pressure12, 13
  • At 1–2, then at 4, 8 and 12 weeks after starting or increasing the dose, especially in heart failure patients8, 12, 13
  • Then 3–6 monthly or more often if clinically required2, 12, 13
  • Hyperkalaemia: patients at high risk include those who are elderly with diabetes, renal impairment or are using an angiotensin converting enzyme (ACE) inhibitor, an angiotensin receptor blocker (ARB) or potassium supplements8
  • Risk of orthostatic hypotension, hyponatraemia and hypochloraemia is increased when combined with a thiazide diuretic10

Thiazide and thiazide-like diuretics:

  • indapamide
  • hydrochlorothiazide
  • chlortalidone
  • Serum biochemistry
  • Blood pressure7
  • Serum biochemistry
  • Blood pressure7, 10
  • 3–6 weeks after starting or as clinically needed7
  • Then 3–6 monthly or more often if clinically required2
  • Risk of hyponatraemia, hypokalaemia and renal impairment7, 8, 11
  • Hyponatraemia and hypokalaemia are uncommon at doses recommended for treating hypertension7
  • At doses used to treat hypertension, thiazide diuretics have a predominantly vasodilatory effect rather than a diuretic effect7

* Bumetanide is not listed on the Pharmaceutical Benefits Scheme or the Repatriation Pharmaceutical Benefits Scheme

**Serum biochemistry: electrolytes, creatinine clearance and urea


A medicines review can be particularly beneficial

Diuretic infographic 2

Older patients taking a diuretic who are frail or cognitively impaired, or have renal impairment, comorbid complexity or polypharmacy, are more likely to experience adverse effects.4, 8, 11, 12, 14 In this population, diuretic-induced adverse effects can contribute to dehydration, falls and fractures, declining attention and cognitive function, worsening renal impairment, reduced quality of life, and institutionalisation.2, 5, 10, 14-16

A collaborative medicines review can be particularly beneficial in detecting, preventing or resolving diuretic-related problems.17, 18

The pharmacist conducting the medicines review can assess and consider:

  • if the diuretic is still needed (see Box 1)
  • pathology results, including electrolyte and renal, and further monitoring required
  • potential drug-drug or drug-disease interactions of concern
  • compliance and knowledge issues, and the patient’s ability to manage their medicines, including their diuretic medicines on sick days and during hot weather.18

Detailed information about a Residential Medication Management Review (RMMR) under item number 903 and a Home Medicines Review (HMR) under item number 900 is available at:

Box 1. Is the diuretic necessary?

Reviewing the need for ongoing use of a diuretic is particularly important in frail or cognitively impaired patients, and in those who have falls or have been using a diuretic long-term. In particular, consider stopping the diuretic where there is no clear benefit, the diuretic is being used for an indication that is no longer an issue, the risks outweigh the benefits, or the treatment no longer aligns with your patient’s preferences.16, 19

Review and consider stopping the diuretic if prescribed for idiopathic ankle oedema or peripheral lymphoedema, or if drug-induced oedema is present:

  • Diuretics are not indicated for the treatment of idiopathic oedema or peripheral lymphoedema.16, 20 Offer to treat the oedema with fitted pressure stockings and limb elevation, and explain to your patient that being physically active may help resolve the oedema.16, 20
  • Some medicines, including dihydropyridine calcium channel blockers, pregabalin and gabapentin, pioglitazone, prednisolone and non-steroidal anti-inflammatory drugs (NSAIDs), can induce or exacerbate peripheral oedema:10, 21, 22
  • Dihydropyridines, such as amlodipine, commonly cause peripheral oedema by redistributing extracellular fluid rather than retaining fluid, which does not respond to treatment with diuretics.10
  • Offer non-pharmacological strategies to address the oedema and stop or change the medicine where possible.10, 21

Pro re nata (PRN) use of diuretics

There is potential for harm associated with the use of PRN “when necessary” orders for medicines, particularly in frail older people.23, 24 Avoid PRN orders for diuretics and prescribe as a stat dose or regular dose or cease.


More frequent monitoring, dose adjustment or temporarily stopping the diuretic may be needed:


When starting medicines that can interact with a diuretic

Drug-drug interactions are more common among older patients, often because they have underlying factors contributing to greater vulnerability which include pathophysiological changes associated with aging and a high number of medicines used to treat multimorbidity.25

Table 2

Table 2. Examples of medicines commonly used by DVA patients that can
interact with diuretics

Medicine combination

Potential adverse effects


A loop diuretic or a thiazide diuretic with an ACE inhibitor or ARB10

  • Renal impairment
  • Hypotension
  • Hypokalaemia10
  • Start, titrate and stop loop diuretics only to manage congestion in heart failure patients.13, 26 To avoid symptomatic hypotension, consider withholding the loop diuretic or reducing the dose for 24 hours before starting an ACE inhibitor or ARB.10, 27
  • When treating patients with heart failure, prioritise use of medicines that decrease mortality, including ACE inhibitors and ARBs over the use of loop or thiazide diuretics.13, 26
  • Consider reducing the dose or stopping the diuretic before making any adjustments to the ACE inhibitor or ARB to avoid renal impairment or symptomatic hypotension.27
  • Avoid NSAIDs (and advise patients to avoid over the counter NSAIDs) when using a loop diuretic together with an ACE inhibitor or ARB as use of these medicines together substantially increases the risk of acute kidney injury.12
  • Monitor renal function, electrolytes and fluid status closely.10

A loop diuretic, potassium sparing diuretic or a thiazide diuretic with NSAIDs, particularly indometacin27

  • Renal impairment27
  • Hyperkalaemia10
  • Reduced diuretic effect8, 27, 28
  • NSAIDs can cause renal impairment, especially in dehydrated or elderly patients.27 People most at risk of adverse effects include older patients with liver cirrhosis, heart failure and renal impairment.27
  • Monitor renal function, electrolytes and fluid status closely.10

Loop diuretic with a thiazide diuretic10

  • Renal impairment
  • Increased diuresis
  • Electrolyte disturbances10
  • Avoid combination, unless advised by other medical specialists.
  • Check renal function within 5 days of starting, then every 5–14 days, depending on the patient’s stability.12 Monitor fluid status closely. Once stable, check at re-prescription or 3–6 monthly unless there is a change in dose, an intercurrent illness or worsening renal function.12

A loop diuretic with a peripheral alpha-1 blocker28

  • Urinary incontinence in older women28
  • Avoid combination where possible.28

A selective serotonin re-uptake inhibitor or carbamazepine with a thiazide diuretic29

  • Hyponatraemia, especially in elderly women29
  • Check electrolytes within two weeks of starting.29

During episodes of acute illness, such as diarrhoea, vomiting or fever

During episodes of acute illness, such as diarrhoea, vomiting or fever, volume depletion, renal impairment and electrolyte disturbances can be made worse with diuretic use.30

  • Monitor patients closely, especially those with heart failure, during episodes of acute illness where there is risk of volume depletion and acute kidney injury. Consider reducing the dose or temporarily withholding the diuretic until the patient is eating and drinking normally again.12, 30 Check renal function if symptoms persist beyond two days.12

The risk of hyperkalaemia may be increased in heart failure patients during acute illnesses

A retrospective study of 64 heart failure patients aged 75 years or over prescribed spironolactone together with an ACE inhibitor and experiencing sepsis, vomiting or diarrhoea found:

  • 36% developed hyperkalaemia (5.5 mmol/L or greater)
  • 11% developed severe hyperkalaemia (6.0 mmol/L or greater)
  • 38% sustained a 50% rise in creatinine concentration.31
  • Gastroenteritis is a common illness in residents in aged care facilities and is associated with high morbidity and mortality.32, 33 Be aware of diuretic use (especially loop diuretics) in residents during episodes of gastroenteritis or other acute illnesses where there is risk of volume depletion and acute kidney injury.30 Ensure staff have clear instructions about diuretic use during this time, particularly if diuretics are included in a dose administration aid, or a fixed-dose combination product, where the diuretic can be overlooked or the dose cannot be adjusted.2, 34
  • An individualised sick day card may be helpful for patients managing their own medicines at home during episodes of fever, diarrhoea or vomiting. Consider including sick day instructions for diuretic use in a General Practitioner Management Plan. To see an example of a Medicine Sick Day Rules card (NHS Scotland and Scottish Patient Safety Program), go to:

During hot weather

In the presence of comorbidities and polypharmacy, the risk of dehydration and heat-related illness during hot weather is significantly increased for many older people.5, 35

A retrospective analysis of 6,700 Australian veterans with an average age of 85 years found that in the year after starting:

  • a diuretic, they were almost two times more likely to be hospitalised for dehydration or a heat-related illness during hot weather, compared to the year before starting the medicine (see Figure 1)5
  • a diuretic together with an ACE inhibitor, they were almost three times more likely to be admitted to hospital for dehydration or a heat-related illness than the year before starting this combination of medicines (see Figure 1).5
Figure 1 Figure 1

Where appropriate, consider reducing the dose of the diuretic or temporarily withholding the diuretic on hot days, or devise an individualised plan for patients who are able to adjust their own diuretic dose. Ensure patients have a good understanding of how to stay hydrated and well during hot weather, and encourage them to make an appointment to see their doctor within a few days if they adjust their diuretic dose.36

For information on managing other medicines during hot weather, refer to the Veterans’ MATES topic, Medicines and hot weather: Reducing the risk of dehydration and heat-related illness, at:

Diuretics, hyponatraemia and falls

  • Hyponatraemia is a common electrolyte disturbance in older people, especially in those who are frail, female or live in aged care facilities.14
  • Mild hyponatraemia can go unrecognised in older people. Symptoms of mental confusion may be misattributed to age-related cognitive decline rather than hyponatraemia. Even mild hyponatraemia can affect cognition, attention, balance, gait and bone strength, increasing the risk of falling, and ultimately reducing quality of life.8, 14, 37, 38
  • Thiazide and thiazide-like diuretics, such as indapamide and hydrochlorothiazide, are common causes of hyponatraemia, particularly if high doses are used.14
  • Consider the risk of hyponatraemia in older people who use thiazide diuretics, including fixed-dose combination products that include a thiazide diuretic, for example, indapamide with perindopril, or hydrochlorothiazide with amiloride, an ACE inhibitor, an ARB or amlodipine.10
  • Mild hyponatraemia that is seemingly asymptomatic requires serum biochemistry for diagnosis.14


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  2. Wehling M. Morbus diureticus in the elderly: epidemic overuse of a widely applied group of drugs. J Am Med Dir Assoc. 2013; 14: 437-442.
  3. Sica D. Diuretic-related side effects: development and treatment. Journal of Clinical Hypertension. 2004; 6(9): 532-540.
  4. Jennings E, Murphy K, Gallagher P, O'Mahony D. In-hospital adverse drug reactions in older adults; prevalence, presentation and associated drugs - a systematic review and meta-analysis. Age Ageing. 2020; 49: 948-958.
  5. Kalisch Ellett L, Pratt N, Le Blanc V, Westaway K, Roughead E. Increased risk of hospital admission for dehydration or heat-related illness after initiation of medicines: a sequence symmetry analysis. J Clin Pharm Ther. 2016; 41: 503-507.
  6. Pirmohamed M et al. Adverse drug reactions as cause of admission to hospital: prospective analysis of 18,820 patients. BMJ. 2004; 329: 15-19.
  7. Therapeutic Guidelines. Melbourne. Therapeutic Guidelines Limited. 2021. Available at: [Accessed June 2021].
  8. BPAC. Drug monitoring. Monitoring diuretics in primary care. 2009. Available at: [Accessed May 2021].
  9. Australian Government Department of Veterans' Affairs DVA Health Claims Database. University of South Australia. QUMPRC. [Accessed June 2021].
  10. Australian Medicines Handbook. Adelaide. Australian Medicines Handbook Pty Ltd. 2021.
  11. Makam A, Boscardin W, Miao Y, Steinman M. Risk of thiazide-induced metabolic adverse events in older adults. J Am Geriatr Soc. 2014; 62: 1039-1045.
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  15. Renneboog B, Musch W, Vandemergel X, Manto M, Decaux G. Mild chronic hyponatremia is associated with falls, unsteadiness, and attention deficits. Am J Med. 2006; 119:71 e71-78.
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  18. Kardachi G et al. Guidelines for comprehensive medication management reviews. 2020. Pharmaceutical Society of Australia. ACT, Australia.
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  20. International Society of Lymphology. The diagnosis and treatment of peripheral lymphedema: 2016 consensus document of the International Society of Lymphology. Lymphology. 2016; 49: 170-184.
  21. Savage R et al. Evaluation of a common prescribing cascade of calcium channel blockers and diuretics in older adults with hypertension. JAMA Intern Med. 2020; 180: 643-651.
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  25. Royal Australian College of General Practice. RACGP aged care clinical guide (Silver book) 5th edn, Part B. Principles of medication management. Available at: [Accessed March 2021].
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  28. American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2019 updated AGS Beers Criteria® for potentially inappropriate medication use in older adults. J Am Geriatr Soc. 2019; 67: 674-694.
  29. Rosner M. Severe hyponatremia associated with the combined use of thiazide diuretics and selective serotonin reuptake inhibitors. Am J Med Sci. 2004; 327: 109-111.
  30. Lea-Henry T, Baird-Gunning J, Petzel E, Roberts D. Medication management on sick days. Australian Prescriber. 2016; 39: 168-173.
  31. Dinsdale C, Wani M, Steward J, O'Mahony M. Tolerability of spironolactone as adjunctive treatment for heart failure in patients over 75 years of age. Age Ageing. 2005; 34: 392-395.
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  33. Trivedi T et al. Hospitalizations and mortality associated with norovirus outbreaks in nursing homes, 2009-2010. JAMA. 2012; 308: 1668-1675.
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Key Points
  • Monitor fluid status, electrolytes and renal function before and after starting a diuretic, and at each re-prescription or every three to six months
  • Devise a patient management plan which includes more frequent monitoring during episodes of acute illness and periods of hot weather
  • Consider a medicines review for patients at high risk of diuretic-induced adverse effects, or if you have any concerns about their medicines use
  • Consider that renal impairment or symptomatic hypotension from diuretic use may impact the optimal use of other medicines that reduce morbidity and mortality