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); Frequency not known (cannot be estimated from the available data).
Listed below are side effects, which have been associated with the administration of furosemide.
Blood and lymphatic System disorders
Uncommon: Thrombocytopenia.
Rare: Leucopenia, eosinophilia, and bone marrow depression (necessitates withdrawal of treatment). The haemopoietic status should therefore be regularly monitored.
Very rare: Agranulocytosis, aplastic anaemia or haemolytic anaemia.
Nervous system disorders
Rare: Paraesthesia, hyperosmolar coma.
Not known: Dizziness, fainting and loss of consciousness (caused by symptomatic hypotension).
Cardiovascular disorders
Uncommon: Cardiac arrhythmias
Furosemide may cause a reduction in blood pressure which, if pronounced may cause signs and symptoms such as impairment of concentration and reactions, light-headedness, sensations of pressure in the head, headache, dizziness, drowsiness, weakness, disorders of vision, dry mouth, Orthostatic intolerance.
Ear and labyrinth disorders
Uncommon: Deafness (sometimes irreversible).
Hearing disorders and tinnitus, although usually transitory, may occur in rare cases, particularly in patients with renal failure, hypoproteinaemia (e.g. in nephritic syndrome) and/or when intravenous furosemide has been given too rapidly.
Endocrine disorders
Glucose tolerance may decrease with furosemide. In patients with diabetes mellitus this may lead to a deterioration of metabolic control; latent diabetes mellitus may become manifest.
Eye disorders
Uncommon: Visual disturbance.
Hepatobiliary disorders
In isolated cases, intrahepatic cholestasis, an increase in liver transaminases or acute pancreatitis may develop.
Hepatic encephalopathy in patients with hepatocellular insufficiency may occur (see Section 4.3).
General disorders and administration site conditions
Uncommon: Fatigue.
Rare: Severe anaphylactic or anaphylactoid reactions (e.g. with shock) occur rarely, fever, malaise.
Vascular disorders
Rare: Vasculitis.
Gastrointestinal disorders
Uncommon: Dry mouth, thirst, nausea, bowel motility disturbances, vomiting, diarrhoea, constipation.
Side effects of a minor nature such as nausea, malaise or gastric upset (vomiting or diarrhoea) may occur but are not usually severe enough to necessitate withdrawal of treatment.
Rare: Acute pancreatitis.
Metabolism and nutritional disorders
As with other diuretics, electrolytes and water balance may be disturbed as a result of diuresis after prolonged therapy.
Furosemide leads to increased excretion of sodium and chloride and consequently increase excretion of water. In addition, excretion of other electrolytes (in particular potassium, calcium and magnesium) is increased. Metabolic acidosis can also occur. The risk of this abnormality increases at higher dosages and is influenced by the underlying disorder (e.g. cirrhosis of the liver, heart failure), concomitant medication (see section 4.5) and diet. Symptomatic electrolyte disturbances and metabolic alkalosis may develop in the form of a gradually increasing electrolyte deficit or e.g. where higher furosemide doses are administered to patients with normal renal function, acute severe electrolyte losses.
Symptoms of electrolyte imbalance depend on the type of disturbance:
Sodium deficiency can occur; this can manifest itself in the form of confusion, muscle cramps, muscle weakness, loss of appetite, dizziness, drowsiness and vomiting.
Potassium deficiency manifests itself in neuromuscular symptoms (muscular weakness, paralysis), intestinal symptoms (vomiting, constipation, meterorism), renal symptoms (polyuria) or cardiac symptoms. Severe potassium depletion can result in paralytic ileus or confusion, which can result in coma.
Magnesium and calcium deficiency result very rarely in tetany and heart rhythm disturbances.
Serum calcium levels may be reduced; in very rare cases tetany has been observed.
Nephrocalcinosis / Nephrolithiasis has been reported in premature infants.
Serum cholesterol (reduction of serum HDL-cholesterol, elevation of serum LDL-cholesterol) and triglyceride levels may rise during furosemide treatment. During long term therapy they will usually return to normal within six months.
As with other diuretics, treatment with furosemide may lead to transitory increases in blood creatinine and urea levels. Serum levels of uric acid may increase and attacks of gout may occur.
The diuretic action of furosemide may lead to or contribute to hypovolaemia and dehydration, especially in elderly patients. Severe fluid depletion may lead to haemoconcentration with a tendency for thromboses to develop.
Musculoskeletal, connective tissue and bone disorders
Muscle spasm has been reported.
Skin and subcutaneous tissue disorders
Uncommon: Photosensitivity
Rare: Skin and mucous membrane reactions may occasionally occur, e.g. itching, urticaria, other rashes or bullous lesions, fever, hypersensitivity to light, exsudative erythema multiforme (Lyell's syndrome and Stevens-Johnson syndrome), bullous exanthema, exfoliative dermatitis, purpura, AGEP (Acute Generalised Exanthematous Pustulosis) and DRESS (Drug Rash with Eosinophilia and Systemic Symptoms).
Not known: Bullous pemphigoid
Renal and urinary disorders
Uncommon: Serum creatinine and urea levels can be temporarily elevated during treatment with furosemide.
Rare: Interstitial nephritis, acute renal failure.
Increased urine production, urinary incontinence, can be caused or symptoms can be exacerbated in patients with urinary tract obstruction. Acute urine retention, possibly accompanied by complications, can occur for example in patients with bladder disorders, prostatic hyperplasia or narrowing of the urethra.
Pregnancy, puerperium and perinatal conditions
In premature infants with respiratory distress syndrome, administration of furosemide tablets in the initial weeks after birth entails an increased risk of a persistent patent ductus arteriosus.
In premature infants, furosemide can be precipitated as nephrocalcinosis/kidney stones.
Rare complications may include minor psychiatric disturbances.
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 Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.