Comprehensive medication guide to Lasix including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$15 copay for generic furosemide; Tier 1 on most commercial and Medicare Part D plans. No prior authorization typically required. Some high-deductible plans may require meeting deductible first.
Estimated Cash Pricing
$10–$43 retail for generic furosemide tablets; as low as $1.80–$2.80 with GoodRx or SingleCare coupons for a 30-day supply. Brand-name Lasix costs $40–$100+ without insurance.
Medfinder Findability Score
75/100
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Lasix is the brand name for furosemide, a powerful loop diuretic (water pill) that has been a cornerstone of cardiovascular medicine since FDA approval in the 1960s. It is prescribed to millions of Americans each year to treat edema (fluid retention) and high blood pressure. Generic furosemide is available and bioequivalent to brand-name Lasix.
Furosemide is FDA-approved for treating edema caused by congestive heart failure, liver disease (cirrhosis), and kidney disease (nephrotic syndrome), as well as for managing high blood pressure (hypertension). It is available as tablets (20 mg, 40 mg, 80 mg), oral solution, injectable vials, and the newly approved Lasix ONYU subcutaneous on-body infusor (October 2025).
Furosemide is not a controlled substance. It requires a prescription but has no DEA scheduling restrictions. It is one of the most commonly prescribed medications in the United States.
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Furosemide works by blocking a critical protein pump called the NKCC2 cotransporter (Na-K-2Cl cotransporter) located in the thick ascending limb of the loop of Henle in the kidneys. This pump normally reabsorbs sodium, potassium, chloride, and water back into the bloodstream during filtration. When furosemide blocks this pump, these electrolytes remain in the tubular fluid and are excreted in the urine — along with large amounts of water through osmosis.
Because the loop of Henle handles approximately 25% of all sodium reabsorption in the kidney, blocking it produces a dramatically more powerful diuretic effect than other classes of diuretics. This is why furosemide is called a "high-ceiling" diuretic — its maximum diuretic effect is far greater than thiazides or potassium-sparing diuretics.
Diuresis typically begins within 30–60 minutes of an oral dose and peaks within 1–2 hours. The full diuretic effect lasts 6–8 hours. Furosemide also has a rapid vasodilatory effect that can begin to relieve pulmonary congestion in heart failure even before significant urine output begins. The terminal half-life is approximately 2 hours.
20 mg — tablet
Low starting dose, often used for hypertension or mild edema
40 mg — tablet
Most common dose for edema in heart failure and kidney/liver disease
80 mg — tablet
Higher dose for more severe edema or diuretic resistance
10 mg/mL — oral solution
For patients who cannot swallow tablets; currently in shortage (March 2026)
10 mg/mL — injection (IV/IM)
For hospital use in acute settings; ongoing ASHP shortage since April 2020
8 mg/mL (30 mg total) — subcutaneous on-body infusor (Lasix ONYU)
FDA approved October 2025 for at-home treatment of edema in chronic heart failure
Furosemide tablets (20 mg, 40 mg, 80 mg) are generally available at most retail pharmacies in 2026. The tablet shortage is not a national concern, though individual pharmacies may temporarily run low on specific generic manufacturers' versions. Furosemide injection has been on the ASHP drug shortage list since April 2020 due to manufacturing issues at multiple producers — this primarily affects hospitals and clinics. Furosemide oral solution entered shortage in March 2026 due to a shortage of an inactive ingredient component, affecting patients who require liquid formulations.
If your pharmacy is out of furosemide tablets, the most efficient way to locate it is to use medfinder — a service that calls pharmacies near you to find which ones can fill your prescription. Results are sent by text, so you know exactly where to go without calling around yourself.
Independent pharmacies often stock different generic manufacturers than large chains and may have furosemide available when a chain pharmacy is temporarily out. It is worth calling local independent pharmacies before assuming the medication is unavailable in your area. For patients who take furosemide regularly, switching to 90-day supplies or mail-order pharmacy can help prevent future out-of-stock situations.
Furosemide is not a DEA-controlled substance, so there are no special prescribing restrictions beyond those that apply to all prescription medications. Any licensed prescriber in the United States can prescribe furosemide during a standard clinical encounter — including via telehealth in most states.
Types of providers who commonly prescribe furosemide:
Cardiologists — most common prescribers for heart failure patients
Nephrologists — for kidney disease, CKD, nephrotic syndrome
Primary Care Physicians (internists, family medicine) — for hypertension and mild-to-moderate edema
Hospitalists — for acute decompensated heart failure management during inpatient stays
Nurse Practitioners (NPs) and Physician Assistants (PAs) — in cardiology, nephrology, and primary care settings
Hepatologists — for cirrhosis with ascites (often combined with spironolactone)
Telehealth prescribing is generally available for furosemide refills and management in patients with established diagnoses. New patients presenting with edema symptoms typically require in-person evaluation, including physical examination and diagnostic testing, before furosemide can be safely prescribed. Telehealth services such as Sesame Care, Teladoc, and MDLive may be able to assist established patients with refills.
No. Lasix (furosemide) is not a DEA controlled substance and is not scheduled under the Controlled Substances Act. It has no addiction or abuse potential. This means there are no special prescribing restrictions related to DEA scheduling — it can be prescribed by any licensed prescriber (physicians, nurse practitioners, physician assistants) during a standard clinical encounter, and there are no limits on the number of refills or refill timing based on controlled substance law.
While furosemide does not have controlled substance restrictions, it still requires a valid prescription from a licensed healthcare provider because it is a potent medication that requires proper medical evaluation and ongoing monitoring of kidney function and electrolytes for safe use. Telehealth prescribing of furosemide is generally permitted in most states since no DEA telehealth exceptions apply.
Common side effects that are expected and generally manageable:
Increased urination (the intended effect)
Dizziness or lightheadedness
Muscle cramps (often from low potassium)
Electrolyte imbalances (low potassium, sodium, magnesium)
Thirst and dry mouth
Nausea
Photosensitivity (increased sun sensitivity)
Serious side effects requiring prompt medical attention:
Ototoxicity — tinnitus (ringing in ears), hearing loss (especially at high IV doses or with aminoglycosides)
Severe dehydration and electrolyte depletion
Dangerous cardiac arrhythmias from severe hypokalemia
Acute kidney injury from excessive fluid depletion
Severe allergic reaction (especially in patients with sulfa allergy)
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Torsemide (Soaanz, Demadex)
Longer-acting loop diuretic with more consistent oral bioavailability (90%) and once-daily dosing. 10-20 mg torsemide ≈ 40 mg furosemide. Often preferred for chronic heart failure management.
Bumetanide (Bumex)
More potent loop diuretic (40x per mg vs furosemide); 1 mg bumetanide ≈ 40 mg furosemide. Higher bioavailability (~80%) with faster onset. Shorter duration may require twice-daily dosing.
Ethacrynic acid (Edecrin)
The only loop diuretic without sulfonamide structure — preferred for patients with sulfa allergies. Higher ototoxicity risk than other loop diuretics.
Spironolactone (Aldactone)
Potassium-sparing diuretic that blocks aldosterone. Not a direct substitute for furosemide but commonly combined with it for heart failure and cirrhosis. Preserves potassium.
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Aminoglycoside antibiotics (gentamicin, amikacin)
majorBoth drugs are ototoxic; combination dramatically increases risk of irreversible hearing loss and nephrotoxicity. Avoid or use with extreme caution.
Ethacrynic acid (Edecrin)
majorContraindicated combination — combined use dramatically increases ototoxicity risk.
NSAIDs (ibuprofen, naproxen, indomethacin)
moderateNSAIDs reduce furosemide's diuretic and antihypertensive effects by inhibiting renal prostaglandins. May increase BUN, creatinine, and potassium.
Digoxin (Lanoxin)
moderateFurosemide-induced hypokalemia increases digoxin toxicity risk — even at therapeutic digoxin levels. Monitor potassium closely.
Lithium
moderateFurosemide reduces lithium excretion, increasing risk of lithium toxicity. Monitor lithium levels frequently when furosemide dose changes.
Cisplatin (platinum-based chemotherapy)
moderateBoth drugs are ototoxic and nephrotoxic; combined use increases risk of hearing damage and kidney injury.
Sucralfate (Carafate)
moderateSucralfate binds furosemide in the gut, reducing absorption by up to 50%. Separate doses by at least 2 hours.
Cyclosporine
moderateCombined use increases risk of gouty arthritis — furosemide raises uric acid and cyclosporine impairs renal urate excretion.
Lasix (furosemide) has been one of medicine's most reliable tools for over six decades. As a generic medication, it is among the most affordable prescription drugs available — as low as $1.80 with discount coupons. Its powerful diuretic action makes it essential for managing fluid overload in heart failure, kidney disease, and liver disease, and for controlling blood pressure.
While furosemide tablets are generally available in 2026, some formulations — particularly the injectable and oral solution — face active shortages. For patients who rely on this medication daily, staying proactive about refills, knowing their backup options (torsemide, bumetanide), and being aware of important drug interactions (NSAIDs, digoxin, lithium) are all critical for safe and consistent therapy.
If you are ever having trouble finding Lasix at your local pharmacy, medfinder can do the pharmacy calling for you — identifying which pharmacies near you have your specific prescription in stock and texting you the results.
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