Furosemide background


Furosemide is a loop diuretic that is used to alleviate the symptoms of breathlessness and oedema. It is the standard first-line therapy for treatment of symptomatic fluid overload in congestive heart failure.

Mode of Action

Loop diuretics inhibit sodium and water reabsorption from the ascending limb of the loop of Henle in the renal tubule and are powerful diuretics. Loop diuretics are potent and act rapidly.

Pharmacological properties of Furosemide

Bioavailability: 60-70% orally but may be reduced by gastrointestinal oedema in heart failure. The bioavailability of subcutaneous Furosemide (compared to IV) is noted to be 100%, with equivalent diuresis to the intravenous route.

Onset of action: 30-60 minutes when administered orally, 30 minutes when administered subcutaneously.

Peak effect: 1-2 hours when administered orally.

Plasma half-life: 50 min- 6 hours in heart failure, 10 hours in end stage renal failure.

Duration of action: 4-6 hours when administered orally, 4 hours when administered subcutaneously.


Increased risk of hypokalaemia with steroids or B-adrenergic receptor agonists (such as Salbutamol, Salmeterol and Terbutaline)

Undesirable Effects

  • Transient pain at site of subcutaneous injection
  • Localised skin reactions (swelling, erythema) – occurred in 3/21 cases recalled by health professionals in a recent regional survey
  • Headaches, dizziness, fever, weakness, restlessness, blurred vision, deafness (usually after rapid IV injection)
  • For full list see manufacturers summary of product characteristics (SPC) via www.medicines.org.uk/emc/


Diuretic effect may be antagonised by corticosteroids or non-steroidal anti-inflammatory drugs NSAIDS; there is an increased risk of nephrotoxicity with NSAIDS. Furosemide-induced hypokalaemia can increase the risk of cardiac arrhythmias with drugs known to prolong the QT interval, such as citalopram and methadone, and concurrent use alongside risperidone in patients with dementia is associated with an increased risk of death. Furosemide is unlikely to be involved in significant drug interactions when used via CSCI for end of life care.

Disclaimer (SPAGG - Rewrite)

This Guide is intended for use by healthcare professionals and the expectation is that they will use clinical judgement, medical, and nursing knowledge in applying the general principles and recommendations contained within. They are not meant to replace the many available texts on the subject of palliative care.

Some of the management strategies describe the use of drugs outside their licensed indications. They are, however, established and accepted good practice. Please refer to the current BNF for further guidance.

While WMPCPS takes every care to compile accurate information , we cannot guarantee its correctness and completeness and it is subject to change. We do not accept responsibility for any loss, damage or expense resulting from the use of this information.