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fen-ill-BYOO-tuh-zone - Pronunciation guide

Brand Names

  • ButaJect
  • ButaPaste
  • ButaTabs E
  • Bute
  • Equi-Phar Phenylbutazone Injection 20%
  • Phenylbutazone Powder
  • Pributazone Boluses


Rx symbolPhenylbutazone is a nonsteroidal anti-inflammatory drug (NSAID) frequently prescribed for lameness, musculosketetal pain, muscle soreness, bone and joint problems, and laminitis.

As one of the most commonly prescribed medications for many musculoskeletel problems, it is often less expensive than other NSAIDs and is well tolerated by most horses. Although it does not speed healing or cure the underlying problem, phenylbutazone, which is quickly absorbed into the blood stream, produces pain relief and fever reduction quickly, thereby making the horse more comfortable.


Phenylbutazone is prescribed for lameness, musculoskeletal pain from soft tissue injury, muscle soreness, bone and joint problems, and laminitis. Some of phenylbutazone's actions may be dose dependent and it should be used under the guidance of appropriate veterinary evaluation and therapy so as not to mask the severity of the problem.

Dosage and Administration

Prescription medicationPhenylbutazone
Method Dosage
(click row for calculator)
Concentration Period Duration
Oral 1-2 mg/lb 1000 mg/tablet Once or twice daily NA
Intravenous injection1 1-2 mg/lb 200 mg/ml Once or twice daily NA



    1. Use a relatively high dose for the first 48 hours, then reduce gradually to a maintenance dose. Maintain lowest dose capable of producing desired clinical response.
    2. Response to phenylbutazone therapy is prompt, usually occurring within 24 hours. If no significant clinical response is evident after 5 days, reevaluate diagnosis and therapeutic approach.
    3. In animals, phenylbutazone is largely metabolized in 8 hours. It is recommended that a third of the daily dose be administered at 8 hour intervals. Reduce dosage as symptoms regress. In some cases, treatment may be given only when symptoms appear with no need for continuous medication. If long-term therapy is planned, oral administration is suggested.
    4. Many chronic conditions will respond to phenybutazone therapy, but discontinuance of treatment may result in recurrence of symptoms.
  • Federal law restricts this drug to use by or on the order of a licensed veterinarian.
  • Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian).
  • The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your equine appears to feel better, the entire treatment plan should be completed to prevent relapse.
  • This medication may be available in forms and concentrations not noted in the above table. Always check the label and literature provided with the medication about the form and concentration and DO NOT USE the calculator if the information differs.
  • Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

The most common side effect is ulceration of the mouth and gastrointestinal tract. Less common side effects include kidney damage, bleeding disorders, and protein loss.


When used at the appropriate dose and according to directions, phenylbutazone is usually a safe and effective drug. Close monitoring and additional care should be taken when it is administered to foals, ponies, older horses, debilitated or dehydrated horses, horses with kidney or liver disease or GI problems, or horses that are pregnant or lactating.

Injection site reactions can occur, and the manufacturer's directions for proper injection should be followed carefully.

Phenylbutazone is FDA approved for use with horses and is a prescription drug. U. S. federal law restricts this drug to use by or on the lawful written or oral order of a licensed veterinarian.

Phenylbutazone is a regulated or prohibited substance in most sanctioned competitions. In each case, the proper regulatory group should be consulted.


Phenylbutazone should not be combined with other anti-inflammatory drugs that tend to cause GI ulcers, such as corticosteroids and other NSAIDs.

Avoid using phenylbutazone with anticoagulant drugs, particularly coumarin derivatives, such as warfarin.


Overdoses of phenylbutazone can cause GI ulcers, protein loss, kidney and liver damage, and death. Early signs of toxicity include loss of appetite, ulcers in the mouth, and depression.


Phenylbutazone TabletsPhenylbutazone Tablets

Superiorbute Phenylbutazone Powder   Superiorbute Phenylbutazone Powder



About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.