At a glance
Effects
- Oedema / fluid reduction: Rapidly clears excess fluid from tissues; used in heart failure, liver cirrhosis, and kidney disease [2].
- Blood pressure lowering: Reduces circulating blood volume, thereby lowering blood pressure [5].
- Rapid diuresis onset: Onset of diuresis is within 30–60 minutes orally and within ~5 minutes intravenously [6].
- Electrolyte excretion: Also increases excretion of potassium, magnesium, and calcium — requiring careful monitoring and sometimes supplementation [4].
Loop diuretic (sulfonamide-derived)
0.5–2 hours (oral/IV)
Oral, IV, IM, subcutaneous
30–60 min (oral); ~5 min (IV)
91–99% (albumin)
About Furosemide
Every point here is drawn from public medical and harm-reduction sources. A bracketed number after a claim — like [1]— is a reference: tap it to open the exact source it's based on (numbered list at the bottom). It is not a rating or score. Educational information, not medical advice.
Product specifics
- Est. delivery
- 3–7 business days · EU tracked
Product details as stated by the vendor (claims, not independently verified). Delivery is our standard EU estimate.
What it is
How it works
Furosemide blocks the Na⁺/K⁺/2Cl⁻ cotransporter in the thick ascending limb of the Loop of Henle, preventing sodium and chloride reabsorption [3]. This disrupts the kidney's concentrating mechanism, causing markedly increased excretion of water, sodium, chloride, potassium, magnesium, and calcium [4]. The result is rapid, powerful fluid removal from the body [1].
Risks & side effects
Most important: The primary risk is profound electrolyte depletion — especially hypokalemia — which can trigger dangerous cardiac arrhythmias, muscle weakness, and circulatory collapse [7]. Ototoxicity (tinnitus, reversible or irreversible hearing loss) is also a serious, dose-related hazard [8].
Common
Serious
- Severe electrolyte imbalance → cardiac arrhythmia [7]
- Circulatory collapse / dehydration from excessive diuresis [8]
- Ototoxicity: tinnitus, reversible or irreversible hearing loss — especially with high doses or IV use [8]
- Vascular thrombosis / embolism from blood volume depletion, particularly in elderly patients [8]
- Hepatic encephalopathy precipitated in cirrhosis patients by sudden electrolyte shifts [11]
- Acute kidney injury, especially with concurrent NSAIDs or aminoglycosides [12]
Safety & harm reduction
- Anuria (no urine output) — absolute contraindication [15]
- Known hypersensitivity to furosemide [15]
- Hepatic coma or states of severe electrolyte depletion before correction [11]
- Hypovolemia or severe dehydration without correction [3]
- Pregnancy: use only if benefit clearly outweighs risk (crosses placenta; adverse animal data) [16]
- Breastfeeding: passes into breast milk and may suppress milk production [15]
- Serum electrolytes (potassium, sodium, magnesium, calcium) — periodically throughout treatment [7]
- Renal function (creatinine, BUN) — especially with dose changes or concurrent nephrotoxic drugs [12]
- Blood pressure and signs of postural hypotension [9]
- Hearing function — if high doses or IV infusions are used [8]
- Blood glucose — furosemide can impair glucose tolerance [13]
- Uric acid levels — hyperuricaemia and gout are possible [14]
- Aminoglycoside antibiotics (e.g. gentamicin, amikacin) — additive ototoxicity and nephrotoxicity; avoid combination [8]
- Ethacrynic acid — contraindicated combination; greatly increased ototoxicity risk [8]
- Cisplatin — increased nephrotoxicity and ototoxicity [12]
- Digoxin — furosemide-induced hypokalemia potentiates digoxin toxicity and arrhythmia risk [7]
- NSAIDs — reduce diuretic effect; increase risk of acute kidney injury [12]
- Lithium — furosemide reduces renal lithium clearance; lithium toxicity risk [15]
- Corticosteroids / ACTH — additive potassium loss [7]
- ACE inhibitors / ARBs — additive hypotension; increased AKI risk [12]
- Antidiabetic drugs — furosemide may blunt glycaemic control; dose adjustment may be needed [12]
- Other antihypertensives / blood-pressure-lowering agents — additive hypotension [9]
- Potassium supplementation (dietary or KCl) and/or an aldosterone antagonist are often added to prevent hypokalemia [11]
- Correct dehydration, electrolyte imbalances, and hepatic coma before starting furosemide [11]
- Start at the lowest effective dose and titrate carefully; the FDA label cautions that excessive amounts can produce profound diuresis [15]
- Avoid rapid IV infusion to reduce ototoxicity risk [8]
- Patients should be advised to rise slowly from lying/sitting positions to manage postural hypotension [9]
Dosage context
Furosemide dosing is strictly individualised and must be medically supervised. For adults with oedema due to heart failure, the FDA-approved initial IV dose is 20–40 mg; oral doses typically begin at 20–80 mg daily and are titrated to response [17]. The FDA label explicitly warns that it is a "potent diuretic" requiring dose and schedule adjustment to each patient's needs [15]. Reported dosing ranges are provided for context only — this is not a prescription.
Sources
- 1.Oxford Medical Education – Furosemide Mechanism
- 2.StatPearls – Furosemide (NCBI Bookshelf)
- 3.Medicine.com – Furosemide Pharmacology
- 4.ClinicalTrials.gov Protocol – Furosemide Background
- 5.DrugBank – Furosemide
- 6.Davis's Drug Guide – Furosemide
- 7.FDA Label – Furosemide Injection USP (DailyMed)
- 8.FDA Prescribing Information – Furosemide Injection (FDA.gov)
- 9.WebMD – Furosemide (Lasix)
- 10.MedlinePlus – Furosemide Drug Information
- 11.StatPearls – Loop Diuretics (NCBI Bookshelf)
- 12.SmPC Interaction Summary (ClinicalTrials Protocol)
- 13.DailyMed – Furosemide Tablets USP 40 mg
- 14.DailyMed – Furosemide Tablet (NDA label)
- 15.RxList – Lasix (Furosemide)
- 16.Medscape – Furosemide Dosing & Interactions
- 17.StatPearls – Furosemide Dosing (NCBI)
This information is provided for educational and harm-reduction purposes only. It is not medical advice. These substances can carry serious health risks; effects and safe use vary by individual. Consult a qualified healthcare professional before use. Legal status varies by country — it is your responsibility to know your local law. We do not encourage misuse.
Other options for Furosemide· 2 offers
Same compound from different labs/brands and pack sizes. Tap a row to switch brand — the price and buy button update instantly.
| Brand | Form | Strength | Pack | Price | Per mg |
|---|---|---|---|---|---|
Sanofi | blister-pack | 40 mg/tab | 12 tab | 38,90 € | €0.081/mg |
GenericSelected | blister-pack | 40 mg/tab | 60 tab | 99,99 € | ★€0.042/mg |