Torsemide
Pyridyl sulfonylurea
Also known as: Demadex · Torem · Unat · Torasemide · AC-3525 · AC 4464 · BM02.015 · JDL-464
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of refractory congestive heart failure | 0.2-0.3 mg/kg | PO | q12-24h | — | 🌎 NA |
| Congestive heart failure | 0.2 mg/kg | PO | once a day to three times a day | — | 🌎 NA |
- Adjunctive treatment of refractory congestive heart failure: When other diuretics have become ineffective
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of refractory congestive heart failure | 0.2-0.3 mg/kg | PO | q12-24h | — | 🌎 NA |
| Congestive heart failure | 0.2 mg/kg | PO | once a day to three times a day | — | 🌎 NA |
- Adjunctive treatment of refractory congestive heart failure: When other diuretics have become ineffective
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Torsemide is a highly potent loop diuretic primarily utilized in veterinary medicine as a "rescue" or adjunctive therapy for congestive heart failure (CHF) in dogs and cats.
- Potency: Approximately 10 times more potent than furosemide.
- Duration: Offers a longer duration of action (~12 hours), allowing for less frequent dosing.
- Potassium-sparing: In dogs, it exhibits less potassium excretion compared to furosemide, though monitoring is still essential.
Clinical Pearl: Torsemide is increasingly favored when patients develop diuretic resistance to furosemide, helping to manage severe pulmonary edema and ascites.
Mechanism of action
Torsemide acts on the thick ascending limb of the loop of Henle in the kidneys.
- It reversibly binds to and inhibits the Na⁺/K⁺/2Cl⁻ (NKCC2) cotransporter at the chloride-binding site → prevents the reabsorption of sodium and chloride.
- This disruption abolishes the hypertonic medullary interstitium → prevents the concentration of urine → results in profound diuresis (excretion of water).
- It also increases the renal excretion of potassium, calcium, magnesium, hydrogen, ammonium, and bicarbonate. In dogs, its potassium-wasting effect is notably less severe than that of furosemide.
Safety & warnings
Contraindications
- Known hypersensitivity to torsemide or other sulfonylureas
- Anuric patients
Adverse effects
- Fluid and electrolyte abnormalities (hyponatremia, hypocalcemia, hypokalemia, hypomagnesemia)
- Prerenal azotemia (secondary to dehydration)
- Gastrointestinal disturbances
- Hematologic effects (anemia, leukopenia)
- Weakness
- Restlessness
- Ototoxicity (rare, associated with rapid IV administration)
Precautions
Use cautiously in patients with significant hepatic dysfunction, hyperuricemia (may increase serum uric acid), or diabetes mellitus (may increase serum glucose).
Note: IV injection should be administered slowly over a period of 2 minutes to minimize the risk of ototoxicity.
Drug interactions
Increased risks for hypotension, particularly in patients who are volume or sodium depleted secondary to diuretics
May increase the ototoxic or nephrotoxic risks of aminoglycosides
May increase the risk for nephrotoxicity development
Can increase the area under the curve of torsemide by 50%; torsemide-induced hypokalemia may increase the potential for digoxin toxicity
Torsemide may reduce lithium clearance
Some NSAIDs may reduce the natriuretic effects of torsemide
Can reduce the diuretic efficacy of torsemide
Torsemide can reduce the excretion of salicylates
Monitoring
- Serum electrolytes (especially potassium, sodium, calcium, magnesium)
- BUN and creatinine
- Blood glucose (if diabetic)
- Hydration status
- Blood pressure (if indicated)
- Clinical signs of edema and patient weight
Pharmacokinetics
Half-life
Absorption
Oral bioavailability is between 80-100% in dogs and cats.
Distribution
Limited information available.
Metabolism
Limited information available.
Elimination
Renal excretion.
Overdose
In dogs, the oral LD50 is >2 grams/kg. Fluid and electrolyte imbalance is the most likely risk associated with an overdose.
- Consider gut emptying protocols for very large or quantity unknown ingestions.
- Acute overdoses should generally be managed by observation with fluid, electrolyte, and acid-base monitoring.
- Supportive treatment should be initiated if required.
Available products
Formulations
- Oral tablets
- Injection (no longer marketed in USA)
Human-labeled
- Torsemide Oral Tablets: 5 mg, 10 mg, 20 mg, & 100 mg (Demadex, generic)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Torsemide tablets should be stored below 40°C; preferably between 15-30°C (59-86°F).
Client information
Torsemide is a powerful "water pill" (diuretic) used to help your pet's body eliminate excess fluid, usually due to severe heart disease.
- Bathroom Habits: Your pet will urinate much more frequently and in larger amounts. Ensure they always have access to fresh drinking water to prevent dehydration.
- Timing: Because it causes increased urination, try not to give the dose right before bedtime unless instructed by your veterinarian.
- What to Watch For: Contact your vet immediately if you notice signs of dehydration or electrolyte imbalance, such as:
- Excessive thirst or lethargy
- Weakness or stumbling
- Vomiting or loss of appetite
- Restlessness or a rapid heart rate
Note: Never change the dose or stop this medication without consulting your veterinarian, as fluid can rapidly build up in the lungs.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.