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rif-AM-pin - Pronunciation guide

Brand Names

  • Rifadin
  • Rimactane


Rx symbolRifampin is a broad-spectrum antibiotic often administered in combination with other antimicrobial agents in treating staphylococcal infections, Corynebacterium pseudotuberculosis, Rhodococcus equi, Streptococcus equi, S. equisimilis, and S. zooepidemicus isolates.

Because resistance to rifampin can develop quickly, it is often used in combination with other antimicrobials. The listed bacteria tend to cause abscesses, and rifampin has excellent penetration of most tissues, including bone and cerebral spinal fluid, as well as abscesses, making it a more potent drug. It is used extensively in combination with erythromycin for the treatment of Rhodococcus equi infections in foals.


Rifampin is used to treat foals and horses when a systemic antibacterial is needed to treat staphylococcal infections and eradicate pathogens located in difficult to reach target areas, such as abscesses.

Dosage and Administration

Prescription medicationRifampin
Method Dosage
(click row for calculator)
Concentration Period Duration
Oral 5-10 mg/kg 150 mg/capsule Daily NA
Oral 5-10 mg/kg 300 mg/capsule Daily NA
For treatment of Rhodococcus Equi1
Oral 5 mg/kg 150 mg/capsule Twice daily NA
Oral 5 mg/kg 300 mg/capsule Twice daily NA


  • 1Use with erythromycin, azithomycin or clarithromycin
  • 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

Side effects are rare in horses. Occasionally, foals on rifampin and erythromycin may develop diarrhea and require prompt action.


Rifampin may cause orange or red discoloration of urine or other bodily fluids, but is not harmful. Rifampin should be used with caution in animals with decreased liver function.

Rifampin is not FDA spproved for use with horses, but is commonly used and an accepted practice. It is a prescription drug and U.S. Federal law restricts this drug to use by or on the lawful written or oral order of a licensed veterinarian.

Although it is unlikely this drug would be used in competition horses, it would not be permitted in drug-free competitions. It is important to check with the individual regulatory agency in each case.


Rifampin may increase the metabolism of some drugs that are also metabolized by the liver, including chloramphenicol, corticosteroids, and anticoagulants.


Overdose increases the risk and severity of the mentioned side effects.


Rifampin Oral Suspension LiquidRifampin Oral Suspension Liquid

Rifampin TabletsRifampin Tablets



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.