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si-proe-HEP-ta-deen - Pronunciation guide

Brand Names

  • Periactin


Rx symbolCyproheptadine is an antihistamine that has anti-serotonin properties and is used in the treatment of conditions involving the pituitary gland, such as pituitary pars intermedia dysfunction and pituitary adenomas, or head shaking, especially in older horses.


Cyproheptadine is used when the pituitary gland becomes enlarged or hypertrophy of the pituitary gland develops. Clinical signs in horses are similar to Cushing's disease in humans. This is a fairly common problem in older horses and ponies. When cyproheptadine is used for the treatment of head shaking, it is usually for its antihistamine properties, especially when an allergic component exists.

Dosage and Administration

Prescription medicationCyproheptadine
Method Dosage
(click row for calculator)
Concentration Period Duration
Oral 0.25 mg/kg 4 mg/tablet 1 Once or twice daily NA


  • 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).
  • Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

Common side effects include sedation, dry mucous membranes, and increased heart rate.


Cyproheptadine should not be used in horses with inflammatory airway disease.

Cyproheptadine has a wide margin of safety. Although it is not FDA approved for use in horses, it is considered accepted practice. It is a prescription drug and U.S. federal law restricts it to use by or on the lawful written or oral order of a licensed veterinarian.

Cyproheptadine is prohibited or regulated in most sanctioned competitions. A veterinarian and the individual regulatory group should be consulted regarding it's use.


Cyproheptadine may have an additive effect when used with other central nervous system depressant drugs.


Overdose causes more pronounced symptoms, similar to side effects mentioned above.


Cyproheptadine Oral SyrupCyproheptadine Oral Syrup

Cyproheptadine Tablets Cyproheptadine 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.