VetSheet

Flunixin Meglumine

3-pyridinecarboxylic acid

Non-steroidal antiinflammatory agent (NSAID)IVIMSCPODogsSmall MammalsFerretsBirdsHorsesCattleSwineSheepGoats

Also known as: Banamine · Flumeglumine · Finadyne · FluNix D · Flunixamine · Flunixiject · Flunizine · Prevail · Suppressor · Vedagesic · Resflor Gold · Sch-14714 · 3-pyridine-carboxylic acid

Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference

Audited v13 dosing evidence

Structured calculator evidence

Analgesic/anti-inflammatory (extra-label)

0.5–2 mg/kgPOIM

Verified clinician required

  • q24h

NA

Governing clinical context (2)
  • The combination product with florfenicol (Resflor Gold®) should not be stored above 30°C (86°F). Once the vial is entered, it should be used within 28 days. The 500 mL vial should not be punctured more than 10 times.
  • All flunixin products should be stored between 2°C and 30°C (36°F-86°F). Flunixin transdermal solution should be used within 6 months of first opening. Vials for injection should be used within 28 days of first puncture, punctured a maximum of 10 times.
High riskVerified clinician requiredformularyProtocol 2023Audit dose-audit-plumb-v13

Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.

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Overview

Flunixin meglumine is a potent, veterinary-only non-steroidal anti-inflammatory drug (NSAID) widely used for its analgesic, anti-inflammatory, and antipyretic properties.

  • Primary Uses: It is FDA-approved in the US for horses, cattle, and swine. In horses, it is considered a gold-standard analgesic for visceral pain associated with colic and is also used for musculoskeletal disorders. In cattle and swine, it is primarily used to control pyrexia associated with respiratory diseases and endotoxemia.
  • Extra-label Use: While historically used in small animals (dogs), its use has been largely supplanted by newer, safer, COX-2 preferential/selective NSAIDs (e.g., carprofen, meloxicam). It is generally considered contraindicated in cats due to high sensitivity to NSAID toxicity.
  • Clinical Pearl: Flunixin is particularly noted for its ability to improve hemodynamics in animals with septic shock and its profound efficacy against visceral pain in ruminants and equines. However, it can mask behavioral and cardiopulmonary signs of endotoxemia or intestinal devitalization in colic patients.

Mechanism of action

Flunixin meglumine is a potent, non-selective inhibitor of the ​cyclooxygenase (COX)​ enzyme system.

  • Mechanism: Cell membrane phospholipids → Phospholipase A2 → Arachidonic Acid → COX-1 / COX-2 → Decreased production of prostaglandins and thromboxanes.
  • By inhibiting prostaglandin synthesis, it reduces inflammation, lowers body temperature (antipyretic), and provides significant analgesia.
  • Unlike some other NSAIDs, flunixin does not appreciably alter gastrointestinal motility in horses, making it highly suitable for colic management.

Safety & warnings

Contraindications

  • Known hypersensitivity to flunixin
  • Cats (generally contraindicated due to availability of safer alternatives)
  • Patients with preexisting GI ulcers (e.g., Equine Gastric Ulcer Syndrome - EGUS)
  • Patients with significant renal, hepatic, or hematologic diseases
  • Breeding bulls (lack of reproductive safety data)
  • Use to ambulate cattle intended for slaughter

Adverse effects

  • Anaphylaxis (especially after rapid IV administration in horses and cattle)
  • IM injection site reactions (localized swelling, induration, stiffness, sweating, and rarely clostridial myonecrosis)
  • Gastrointestinal ulceration (oral and gastric ulcers, especially with prolonged use or high doses)
  • Renal ischemia and nephrotoxicity (especially in dehydrated patients, dogs, and birds)
  • Hematochezia and hematuria (reported in cattle treated > 3 days)
  • Hypoproteinemia and hematologic abnormalities

Precautions

Important Warnings

  • Masking of Symptoms: In horses with colic, flunixin may mask the behavioral and cardiopulmonary signs associated with endotoxemia or intestinal devitalization.
  • Injection Site Risks: IM injections in horses and cattle can cause significant tissue irritation and rarely clostridial myonecrosis. Rapid IV administration can cause anaphylactic-like reactions.
  • Intra-arterial Injection: Accidental intra-arterial injection may cause CNS stimulation (hysteria), ataxia, hyperventilation, and muscle weakness.
  • Pregnancy: Use cautiously in pregnant animals (FDA Class C equivalent).

Drug interactions

Aspirin

May decrease plasma levels of flunixin and increase the likelihood of GI adverse effects (blood loss)

Cyclosporine

May increase cyclosporine blood levels and increase the risk for nephrotoxicity

Digoxin

May increase serum levels of digoxin; use with caution in severe cardiac failure

Enrofloxacin

Increases AUC and elimination half-life of both flunixin and enrofloxacin in dogs

Furosemide & other diuretics

May reduce the saluretic and diuretic effects of the diuretic

Methotrexate

Serious toxicity has occurred with concomitant use; use together with extreme caution

Nephrotoxic agents (e.g., aminoglycosides, amphotericin B)

Increased risk of synergistic nephrotoxicity

Probenecid

May cause a significant increase in serum levels and half-life of flunixin

Warfarin

May increase the risk for bleeding

Monitoring

  • Analgesic, anti-inflammatory, and antipyretic efficacy
  • Gastrointestinal effects (especially in dogs and horses)
  • CBCs and occult blood in feces with chronic use in horses
  • Renal parameters (BUN, Creatinine, USG) in susceptible species or dehydrated patients

Pharmacokinetics

Half-life

Horses1.6-4.2 hoursDogs3.7 hours

Absorption

Rapidly absorbed following oral administration in horses (average bioavailability 80%). Peak serum levels occur in 30 minutes. Onset of action is generally within 2 hours; peak response between 12-16 hours, and duration lasts up to 30 hours.

Distribution

Highly bound to plasma proteins (>99% cattle, 92% dogs, 87% horses). Volume of distribution ranges from approximately 0.15 L/kg in horses to 0.78 L/kg in cattle.

Metabolism

Elimination is primarily via hepatic routes.

Elimination

Excreted primarily via biliary routes. Detectable in equine urine for at least 48 hours after a dose.

Overdose

Acute overdosage should be handled by using established protocols of emptying the gut (if oral ingestion and practical/possible) and treating the patient supportively.

  • Gastric Ulceration: A distinct possibility in horses that have received overdoses. Consider using prophylactic anti-ulcer medications (e.g., omeprazole) in overdosed horses.
  • Renal Protection: Ensure adequate hydration and monitor renal values closely.

Available products

Formulations

  • Injection (50 mg/mL)
  • Oral Paste (1500 mg/syringe)
  • Oral Granules (250 mg/sachet)
  • Combination Injection (16.5 mg/mL flunixin + 300 mg/mL florfenicol)

Veterinary

  • Flunixin Meglumine for Injection: 50 mg/mL in 50 mL, 100 mL and 250 mL vials
  • Flunixin Meglumine Oral Paste: 1500 mg/syringe in 30 gram syringes
  • Flunixin Meglumine Oral Granules: 250 mg in 10 gram sachets; 500 mg in 20 g sachets
  • Flunixin 16.5 mg/mL with Florfenicol 300 mg/mL Injection (Resflor Gold)

Regulatory status

No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

Storage & stability

Store all flunixin products between 2-30°C (36-86°F). Do not mix flunixin meglumine injection with other drugs due to unknown compatibilities. Resflor Gold should not be stored above 30°C (86°F), should be used within 28 days of first puncture, and the 500 mL vial should not be punctured more than 10 times.

Client information

For Pet and Livestock Owners

  • Administration: Follow your veterinarian's exact instructions. If injecting intramuscularly (IM) in horses or dogs, be aware it can cause pain and swelling. ​(Note: In swine, IM injection is specifically labeled for the neck muscles only).​
  • Food Animal Restrictions: The IM route is extra-label in cattle and requires longer withdrawal times. Do not use flunixin to make injured or non-ambulatory cattle walk for slaughter purposes.
  • Side Effects to Watch For: Stop the medication and contact your veterinarian immediately if you notice signs of stomach ulcers (loss of appetite, dark/tarry stools, depression) or changes in urination.
  • Missed Doses: If the first dose does not control the pain, do not give additional doses without consulting your veterinarian, as it increases the risk of toxicity without adding benefit.

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.