Intended for healthcare professionals

Practice Practical Prescribing

Thiazide diuretics

BMJ 2024; 384 doi: (Published 05 February 2024) Cite this as: BMJ 2024;384:e075174
  1. Steven D Anisman, invasive cardiologist1,
  2. Stephen B Erickson, clinical nephrologist2,
  3. Kim M Fodor, internist3
  1. 1North Country Cardiology, Newport, VT, USA
  2. 2Mayo Clinic, Division of Nephrology and Hypertension, Rochester, MN, USA
  3. 3SVMC Internal Medicine, Bennington, VT, USA
  1. Correspondence to S D Anisman Steven.Anisman{at}

What you need to know

  • Thiazide type and thiazide-like diuretics are effective antihypertensives, and are useful for mild hypervolaemia, or for potentiating loop diuretics

  • They are first line medications for treating hypertension in many countries, but not in the UK

  • Measure serum electrolytes and creatinine one to two weeks after initiating a thiazide diuretic to assess for electrolyte disturbances, most commonly hyponatraemia

A 56 year old woman with hypertension and no other comorbidities develops swollen ankles while taking amlodipine. She has normal renal function and you are considering adding a thiazide or thiazide-like diuretic. What issues do you need to consider and what do you need to discuss with the patient?

How often are thiazides prescribed and how do they work?

Thiazide-type diuretics are those that contain a benzothiadiazine molecule, while thiazide-like diuretics do not. However, both have identical effects on the nephron,1 and will be discussed in this article as “thiazides” unless otherwise noted. Thiazide diuretics are indicated primarily for the treatment of hypertension,2 although they are also used as direct diuretics, to increase urine output3 for conditions such as heart failure, nephrotic syndrome, or hepatic failure.

Thiazides are prescribed less frequently than some other antihypertensives but are a commonly prescribed class of diuretics worldwide (table 1). Bendroflumethiazide is rarely prescribed in the US, but it is the most commonly prescribed thiazide diuretic in the UK even though it is no longer the preferred diuretic for treating hypertension.

View this table:
Table 1

Frequency of prescriptions of diuretics

A Cochrane review recommends thiazides as the first choice for treating hypertension in patients who do not have a specific indication for an alternative class of anti-hypertensive (such as coronary disease), based on the quality of evidence supporting their ability to reduce adverse endpoints (mortality, stroke, and heart attack).8 However, in the UK, these recommendations have not been incorporated in the most recent National Institute for Health …

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