Cyproheptadine
(sip-roe-hep-ta-deen)
Description: Antihistamine; Anti-serotonin Agent
Other Names for this Medication: Periactin®

Cyproheptadine has two main effects: blocking histamine and blocking serotonin. Cyproheptadine blocks histamine’s effects and reduces itchiness associated with allergies. This drug is most commonly used in dogs and cats for its effects on serotonin release. Serotonin blockade can be useful as an appetite stimulantin cats as well as a treatmentfor serotonin syndrome in affected dogs and cats. The FDA has approved this drug for use in humans, but it is not officially approved for use in animals. The FDA allows veterinarians to prescribe products containing this drug in different species or for other conditions in certain situations. You and your veterinarian can discuss why this drug is the most appropriate choice.

Common but not serious side effects include: The most common side effect, which is often desirable, is sleepiness. Most animals will become tolerantto this effect with time and will not get as sleepy when given the medication. Dry mouth and trouble urinating (eg, straining) are possible but not common.
Cats, in particular, may become unusually excited while taking this drug. Infrequently, cyproheptadine may cause gastrointestinal distress (eg, vomiting, decreased appetite, diarrhea). You don’t have to be overly concerned if you see any of these signs unless they are severe, worsen, or continue to be a problem.

Contact your veterinarian if you have any concerns.