The following ratings are used for expressing the frequency of adverse reactions:
Very common (≥1/10)
Common (≥1/100 to <1/10)
Uncommon (≥1/1,000 to <1/100)
Rare (≥1/10,000 to <1/1,000)
Very rare (<1/10,000)
Not known (cannot be estimated from the available data)
The frequency ratings for adverse reactions are based on literature data and relate to studies in which a total of 1,387 patients were treated with various dosages of furosemide in various indications.
Blood and lymphatic system disorders
Common: haemoconcentration (if diuresis is excessive).
Uncommon: thrombocytopenia.
Rare: eosinophilia, leukopenia.
Very rare: haemolytic anaemia, aplastic anaemia, agranulocytosis.
Signs of agranulocytosis may include fever with chills, mucosal changes and sore throat.
Immune system disorders
Uncommon: allergic mucocutaneous reactions (see “Skin and subcutaneous tissue disorders”).
Rare: severe anaphylactic and anaphylactoid reactions such as anaphylactic shock (for treatment, see section 4.9). Initial signs of shock include skin reactions, such as flushing or urticaria, restlessness, headache, sweating, nausea, cyanosis.
Not known: exacerbation or activation of systemic lupus erythematosus.
Metabolism and nutrition disorders (see section 4.4)
Very common: electrolyte disturbances (including symptomatic), dehydration and hypovolaemia (especially in elderly patients), blood triglycerides increased.
Common: hyponatraemia and hypochloraemia (especially with restricted sodium chloride intake), hypokalaemia (especially with concomitant reduction of potassium intake and/or increased potassium losses, e.g. due to vomiting or chronic diarrhoea), blood cholesterol increased, blood uric acid increased and gout flare.
Uncommon: glucose tolerance decreased and hyperglycaemia. In patients with manifest diabetes mellitus, this can lead to a worsening of metabolic status. Latent diabetes mellitus may become manifest (see section 4.4).
Not known: hypocalcaemia, hypomagnesaemia, metabolic acidosis, pseudo-Bartter syndrome (associated with misuse and/or long-term use of furosemide).
Commonly observed symptoms of hyponatraemia are apathy, calf cramps, anorexia, asthenia, drowsiness, vomiting and confusional state.
Hypokalaemia can manifest as neuromuscular (muscle weakness, paraesthesia, paresis), intestinal (vomiting, constipation, meteorism), renal (polyuria, polydipsia) and cardiac symptoms (impulse formation and conduction disturbances). Severe potassium losses can lead to paralytic ileus or impaired consciousness and even coma.
Hypocalcaemia can induce tetany in rare cases.
As a result of hypomagnesaemia, tetany or occurrence of cardiac arrhythmias has been observed in rare cases.
Nervous system disorders
Common: hepatic encephalopathy in patients with hepatic impairment (see section 4.3).
Rare: paraesthesias.
Not known: dizziness, fainting and loss of consciousness, headache.
Ear and labyrinth disorders
Uncommon: hearing disorders, mostly reversible, especially in patients with renal impairment or hypoproteinaemia (e.g. in cases of nephrotic syndrome) and/or if intravenous injections are too rapid. Deafness (sometimes irreversible).
Rare: tinnitus.
Vascular disorders
Very common (with intravenous infusions): hypotension including orthostatic syndrome (see section 4.4).
Rare: vasculitis.
Not known: thrombosis (especially in elderly patients).
If diuresis is excessive, circulatory problems (including circulatory collapse) may occur, especially in elderly patients and children, which mainly manifest as headache, dizziness, visual disturbances, dry mouth and thirst, hypotension and orthostatic dysregulation.
Gastrointestinal disorders
Uncommon: nausea.
Rare: vomiting, diarrhoea.
Very rare: acute pancreatitis.
Hepatobiliary disorders
Very rare: intrahepatic cholestasis, transaminases increased.
Skin and subcutaneous tissue disorders
Uncommon: pruritus, urticaria, rashes, bullous dermatitis, erythema multiforme, pemphigoid, exfoliative dermatitis, purpura, photosensitivity.
Not known: Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis (AGEP), drug rash with eosinophilia and systemic symptoms (DRESS), lichenoid reactions.
Musculoskeletal and connective tissue disorders
Not known: cases of rhabdomyolysis have been reported, often in association with severe hypokalaemia (see section 4.3).
Renal and urinary disorders
Very common: blood creatinine increased.
Common: urine volume increased.
Rare: tubulointerstitial nephritis.
Not known: urine sodium increased, urine chloride increased, blood urea increased, symptoms of urinary obstruction (e.g. in patients with prostatic hypertrophy, hydronephrosis, ureteric stenosis) and even urinary retention with secondary complications (see section 4.4), nephrocalcinosis and/or nephrolithiasis in preterm infants (see section 4.4), renal failure (see section 4.5).
Congenital, familial and genetic disorders
Not known: increased risk of patent ductus arteriosus when preterm infants are treated with furosemide in the first weeks of life.
General disorders and administration site conditions
Rare: fever.
Not known: after intramuscular injection, local reactions such as pain.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.