Flunixin Meglumine for Horses: Uses, Dosing & Side Effects

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Flunixin meglumine is a prescription nonsteroidal anti-inflammatory drug (NSAID) used in horses to reduce pain, inflammation, and fever. Many pet parents know it by the brand name Banamine. In the U.S., labeled equine forms include injectable solution and oral paste, and the drug is commonly used under your vet’s direction for short-term pain control.

In horses, flunixin is especially valued because it can help with visceral pain, including pain linked with colic, and with musculoskeletal inflammation. It also has strong anti-inflammatory effects in certain urgent situations, such as acute eye inflammation, when your vet decides it is appropriate.

Even though it is widely used, flunixin is not a casual medication. Like other NSAIDs, it can affect the stomach and intestines, kidneys, and blood flow to important tissues. That means the safest dose, route, and duration depend on the horse’s hydration status, age, underlying disease, and what other medications are being used.

The FDA-labeled uses of flunixin meglumine in horses are the alleviation of inflammation and pain associated with musculoskeletal disorders and the alleviation of visceral pain associated with colic. In practice, that means your vet may reach for flunixin when a horse is painful, inflamed, febrile, or showing signs that suggest abdominal pain.

Common real-world uses include short-term treatment of colic pain, lameness or soft-tissue inflammation, and fever when inflammation is part of the problem. Merck also notes that systemic flunixin is an important part of initial treatment for acute equine uveitis, where rapid control of inflammation can help protect vision.

Flunixin can make a horse look more comfortable before the underlying problem is fully diagnosed. That is helpful, but it can also mask worsening disease. If your horse has colic, eye pain, dehydration, diarrhea, kidney concerns, or ongoing fever, your vet should guide treatment and recheck the horse if signs persist or return.

Always use the exact dose and route your vet prescribes. For labeled equine use, the common dose is 0.5 mg/lb (1.1 mg/kg) once daily. For musculoskeletal pain, the injectable product label allows IV or IM administration once daily for up to 5 days. For colic pain, the same dose is used, but intravenous administration is recommended for faster relief.

For the oral paste, the labeled dose is also 0.5 mg/lb (1.1 mg/kg) once daily. The syringe is calibrated by body weight, and one 30 g syringe contains enough medication to treat a 1,000 lb horse once daily for 3 days. Label directions state treatment should not exceed 5 consecutive days.

Your vet may adjust the plan for specific situations. For example, Merck describes acute uveitis protocols that may start at 1.1 mg/kg IV, followed by 0.5 to 1.1 mg/kg by mouth every 12 hours for 5 to 7 days, then tapering in some horses. Longer use increases risk, so horses on extended therapy may need monitoring such as kidney values and checks for gastrointestinal injury.

Do not change the dose, double up after a missed dose, or combine flunixin with another pain reliever unless your vet tells you to. If a horse needs repeated doses for colic, that is a reason to update your vet right away, because the pain source still needs to be identified and treated.

Many horses tolerate short courses of flunixin well, but side effects can happen even at recommended doses. The biggest concerns are gastrointestinal ulceration, right dorsal colitis, and kidney injury, especially if a horse is dehydrated, already has kidney disease, or receives the drug too often or for too long.

Watch for warning signs such as loss of appetite, soft manure or diarrhea, colic signs, weight loss, lethargy, ventral edema, reduced drinking, or changes in urination. Cornell’s NSAID guidance also highlights broader red flags seen with this drug class, including behavior changes, black or bloody manure, and jaundice. If you notice any of these, stop the medication and contact your vet promptly.

The injectable form has route-specific risks. The label reports local swelling, sweating, induration, and stiffness after intramuscular injection, and in rare cases fatal or nonfatal clostridial infections have been associated with IM use in horses. Rare anaphylactic-like reactions have also been reported, especially after IV use.

If a horse becomes suddenly weak, severely depressed, more painful, swollen under the belly, or stops eating after receiving flunixin, treat that as urgent. Those signs can point to a serious NSAID complication or progression of the original disease.

The most important interaction rule is this: do not combine flunixin with other NSAIDs or corticosteroids unless your vet specifically directs it. That includes drugs such as phenylbutazone, firocoxib, ketoprofen, aspirin, dexamethasone, prednisolone, and triamcinolone. Combining these medications can sharply increase the risk of stomach and intestinal ulceration, right dorsal colitis, and kidney injury.

Your vet will also use extra caution if your horse is dehydrated or receiving other drugs that can stress the kidneys, such as some antibiotics or IV medications used in hospitalized horses. In those cases, the interaction is not always a direct drug-to-drug conflict. Sometimes it is the combination of illness, reduced blood flow, and medication effects that raises risk.

Tell your vet about every medication, supplement, ulcer product, joint product, and over-the-counter item your horse is getting. That includes recent medications, not only current ones, because your vet may want a washout period before switching from one NSAID to another.

If your horse is pregnant, nursing, breeding, has a history of ulcers, kidney disease, diarrhea, or prior NSAID sensitivity, bring that up before the first dose. Those details can change whether flunixin is a good fit or whether another option makes more sense.