Furosemide Side Effects
Some side effects of furosemide may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to furosemide: oral liquid, oral solution, oral tablet
Get emergency medical help if you have any of these signs of an allergic reaction while taking furosemide: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using furosemide and call your doctor at once if you have a serious side effect such as:
ringing in your ears, hearing loss;
itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
severe pain in your upper stomach spreading to your back, nausea and vomiting;
weight loss, body aches, numbness;
swelling, rapid weight gain, urinating less than usual or not at all;
chest pain, new or worsening cough with fever, trouble breathing;
pale skin, bruising, unusual bleeding, feeling light-headed, rapid heart rate, trouble concentrating;
low potassium (confusion, uneven heart rate, leg discomfort, muscle weakness or limp feeling);
low calcium (tingly feeling around your mouth, muscle tightness or contraction, overactive reflexes);
headache, feeling unsteady, weak or shallow breathing; or
severe skin reaction -- fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Less serious side effects of furosemide may include:
diarrhea, constipation, stomach pain;
dizziness, spinning sensation; or
mild itching or rash.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to furosemide: compounding powder, injectable solution, intravenous solution, oral liquid, oral solution, oral tablet
Volume depletion may predispose some patients to deep venous thrombosis.
In a study of patients with congestive heart failure (CHF) due to myocardial infarction, furosemide has been shown to decrease left ventricular end diastolic pressure and decrease peripheral vascular resistance before a significant increase in urine output or decrease in arterial blood pressure is observed.
However, in patients with advanced, chronic CHF, the IV administration of furosemide may result in an acute vasoconstrictor response associated with an acute increase in vasoconstrictive hormones, such as norepinephrine, renin, and arginine vasopressin (AVP).
After central venous catheter administration of furosemide 125 mg, 3rd degree AV heart block was observed in a very ill patient (one case report). Because no other etiology was found, it was believed that the relatively high pH of furosemide and/or the rapid rate of administration caused the arrhythmia.
Furosemide may increase cholesterol and triglyceride serum levels.
Cardiovascular side effects have commonly included intravascular volume depletion and hypotension. Signs and symptoms of furosemide-induced volume depletion have included thirst, muscle cramps, weakness, dizziness, lightheadedness, syncope, tachycardia, palpitations, and dry skin. In addition, these signs and symptoms have often been associated with a hypochloremic metabolic alkalosis and increased serum BUN and creatinine.
Hyperuricemia is usually a benign side effect, but may be important in some patients with a history of gout.
Although less so than with thiazide diuretics, furosemide may induce a relative glucose intolerance, which may be important in some patients, such as diabetics.
Rare instances of hypocalcemia have been reported in patients with latent hypoparathyroidism, in which case both calcium and magnesium replacement may be helpful.
Metabolic abnormalities may be more likely and severe in patients with liver disease. If a patient has severe liver disease, frequent monitoring of the patient's electrolytes is recommended.
Calcium balance appears to remain neutral during treatment with a loop diuretic (i.e., furosemide, bumetanide). Although loop diuretics cause an increase in renal calcium excretion, this appears to be compensated for by a parathyroid-dependent increase in 1,25-dihydroxyvitamin D levels, which increases intestinal calcium absorption. Bone metabolism does not appear to be significantly affected by loop diuretics.
Metabolic side effects including hypokalemia, hypomagnesemia, and an increase in serum uric acid, have been relatively common especially with higher doses. Although less common than with thiazide diuretics, mild hyperlipidemia and hypercholesterolemia have been associated with the use of furosemide. A single study suggests that chronic furosemide therapy is associated with clinically significant thiamine deficiency via urinary thiamine loss. This may be important in patients with congestive heart failure since thiamine deficiency may impair cardiac performance.
Furosemide has been reported to displace thyroxine (T4) from protein-binding sites. When administered in large intravenous doses (above 80 mg), a transient increase in serum free T4 concentrations and decrease in serum total T4 concentrations have been reported.
Hypersensitivity reactions to furosemide have been uncommon. Rashes, fever, malaise, interstitial nephritis, and eosinophilia have been reported. Severe anaphylactic or anaphylactoid reactions (e.g., with shock) have been reported.
Furosemide contains a sulfur moiety, and may induce an allergic reaction in some patients with a history of sulfa sensitivity.
Rare cases of interstitial nephritis and hypersensitivity angiitis associated with furosemide have been reported.
The doses of furosemide in cases of tinnitus, vertigo, or deafness ranged from 0.24 grams IV given over 40 minutes to 3 grams IV in divided doses over 9 hours and 2 grams IV in a single dose. It is recommended that infusion rates not exceed 4 mg/min to minimize the risk of ototoxicity.
Ototoxicity may be more likely and more severe due in patients with renal insufficiency.
Nervous system side effects have included headaches and dizziness. Cases of tinnitus and reversible or irreversible hearing impairment and deafness have been reported.
Gastrointestinal side effects have included hepatic encephalopathy in patients with hepatocellular insufficiency, pancreatitis, jaundice (intrahepatic cholestatic jaundice), anorexia, oral and gastric irritation, cramping, diarrhea, constipation, nausea, and vomiting.
Cholestatic jaundice may be important in patients with liver disease.
Hepatic side effects have included rare cases of cholestatic jaundice and increased liver enzymes.
Hematologic side effects have included eosinophilia. Thrombocytopenia, aplastic anemia, and leukopenia have been very rare.
One patient experienced acute generalized exanthematic pustulosis a few hours after receiving intravenous furosemide.
Dermatologic reactions, such as bullous pemphigoid have been reported in rare cases. Exfoliative dermatitis, erythema multiforme, purpura, photosensitivity, urticaria, rash, Stevens-Johnson Syndrome, toxic epidermal necrolysis, and pruritus have also been reported.
At least two cases of Sweet syndrome related to use of furosemide have been reported. In one case, Sweet syndrome was characterized by low-grade fever, tender, papular, erythematous, nonpruritic skin lesions on the arms and thighs, and redness in the eyes with photophobia. Papuloerythroderma of Ofuji has also been associated with furosemide use.
Dermatologic side effects reported postmarketing have included drug rash with eosinophilia and systemic symptoms and acute generalized exanthematous pustulosis.
Renal side effects have included nephrocalcinosis/nephrolithiasis in premature infants treated with furosemide, therefore renal function should be monitored and renal ultrasonography performed.
More furosemide resources
- furosemide MedFacts Consumer Leaflet (Wolters Kluwer)
- furosemide Advanced Consumer (Micromedex) - Includes Dosage Information
- Furosemide Prescribing Information (FDA)
- Furosemide Professional Patient Advice (Wolters Kluwer)
- Furosemide Monograph (AHFS DI)
- Lasix Prescribing Information (FDA)
- Lasix Consumer Overview
- Lasix MedFacts Consumer Leaflet (Wolters Kluwer)
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