Furosemide monitoring

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Topics: FurosemideMonitoring
Using this page · Individualise medicines monitoring

This medicines monitoring page has been written using publications and expert opinion. It is designed to save clinician time, but not replace professional responsibility. When using this page you should: ensure an individualised monitoring plan is developed in partnership with the patient and take account of any locally agreed advice and guidance.

Before starting


  • Baseline
    • Blood pressure
    • Electrolytes
    • Serum creatinine (for creatinine clearance)

After started or dose changed


  • After 1-2 weeks; or after 5-7 days in high risk patients
    • Blood pressure
    • Electrolytes
    • Serum creatinine (for creatinine clearance)

Defining high risk patients

High risk patients includes those:

  • With existing chronic kidney disease (stage 3 or higher)
  • Aged 60 years or over
  • With relevant comorbidities such as diabetes mellitus or peripheral arterial disease.
  • Taking a combination of a diuretic plus an angiotensin-converting enzyme (ACE) inhibitor, an angiotensin-II receptor antagonist (AIIRA), or an aldosterone antagonist
  • Those taking digoxin or drugs that prolong the QT interval (such as amiodarone).
  • Those with paroxysmal arrhythmias, unstable angina, or chronic liver disease.

Ongoing once stable


  • 6 monthly
    • Electrolytes
    • Serum creatinine (for creatinine clearance)

Abnormal results

Renal function

Take appropriate action dependent on renal function monitoring.

Serum creatinine level increase of more than 20%; eGFR falls more than 15%

Re-measure renal function within 2 weeks.

Serum creatinine level increase of more than 30-50%, or value greater than 200 micromol/L; or eGFR less than 30 mL/min/1.73 m2

Ensure prompt clinical review of volume status. Reduce dose or stop if patient hypovolaemic.
Re-measure renal function within 1 week.

Serum creatinine level increase of more than 50%, or value greater than 256 micromol/L; eGFR approximately 20–25 mL/min/1.73 m2

Assess volume status and respond:

  • If patient hypovolaemic then stop furosemide.
  • If patient not hypovolaemic then:
    • check blood pressure
    • review other renal function tests, including electrolytes and proteinuria
    • review other medications to identify nephrotoxic agents

If any uncertainty, seek specialist advice urgently.

Potassium level

Take appropriate action dependent on potassium level monitoring.

Level decreases to less than 3 mmol/L (or 4 mmol/L in high-risk people)

Review the diuretic treatment dose or consider stopping it.

Level decreases to less than 2.5 mmol/L (or 3.5 mmol/L in high-risk people)

Seek specialist advice urgently.



Use furosemide with caution in patients with diabetes as it can exacerbate diabetes (but hyperglycaemia less likely than with thiazides).

Fluid loss if acutely unwell

If patients develop diarrhoea and vomiting while on furosemide treatment, they should maintain their fluid intake and stop furosemide for 1 – 2 days until they recover. If symptoms persist beyond 2 days, renal function should be checked.


Update history

  1. Reference link to NICE CKS updated
  1. Published

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