Cyproheptadine
Cyproheptadine is used empirically as an appetite stimulant and for selected allergic or behavioral indications.
Group
Antihistamine and serotonin antagonist
Mechanism of Action
Blocks histamine and serotonin receptors and has antimuscarinic activity.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Allergic signs | 0.5–1.1 mg/kg | PO | Every 8–12 h | |
| Allergic signs | 0.3–2 mg/kg | PO | Every 12 h | |
| Appetite stimulation | 0.2 mg/kg | PO | Every 12 h | Less frequent dosing may suffice for mild inappetence. |
| Serotonin syndrome adjunct | 1.1 mg/kg | PO | Every 4–6 h | Repeat only as needed until signs resolve; combined with withdrawal of serotonergic drugs and supportive care. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Allergic signs | 0.5–1.1 mg/kg | PO | Every 8–12 h | |
| Allergic signs | 2–4 mg/animal | PO | Every 12–24 h | |
| Appetite stimulation | 2 mg/animal | PO | No repeat interval is assigned in the source. | |
| Empirical asthma adjunct | 1–2 mg/animal | PO | Every 12 h | Efficacy for airway inflammation is unproven. |
| Inappropriate urination — Initial | 2 mg/animal | PO | Every 12 h | |
| Inappropriate urination — Maintenance | 1 mg/animal | PO | Every 12 h | |
| Appetite stimulation | 2–4 mg/animal | PO | Every 12–24 h | |
| Appetite stimulation | 1–4 mg/animal | PO | Every 12–24 h | |
| Appetite stimulation | 0.35–1 mg/kg | PO | Every 12 h | |
| Appetite stimulation with renal insufficiency | 1 mg/animal | PO | Every 12 h | |
| Allergic signs | 2 mg/animal | PO | Every 12 h | |
| Allergic signs | 1.1 mg/kg | PO | Every 12 h | |
| Serotonin syndrome adjunct | 2–4 mg/animal | PO | Every 4–6 h | Repeat only as needed until signs resolve, with supportive care. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Empirical antihistamine treatment | 0.5 mg/kg | PO | Every 12 h | General equine dose; a specific indication is not assigned in the dosage bullet. |
| Head shaking | 0.3 mg/kg | PO | Every 12 h | |
| Photic head shaking | 0.3–0.6 mg/kg | PO | Every 12 h | |
| Historical pituitary dysfunction adjunct | 0.25 mg/kg | PO | Every 24 h | Up to 56 days; Historical 4–8-week trial; if no response the source increases to twice daily, but pergolide is generally preferred. |
| Historical pituitary dysfunction adjunct | 65–125 mg/animal | PO | Every 24 h | Separate fixed-dose historical alternative; do not substitute for a patient-specific weight-based plan. |
| Pituitary dysfunction combination adjunct | Reference only | PO | Cyproheptadine 0.5 mg/kg orally every 12 hours has been added when response to pergolide 0.006 mg/kg is limited and endocrine tests remain abnormal; continue clinical, glucose and endocrine monitoring. |
Indications
- Appetite stimulation
- Allergic signs
- Empirical feline airway treatment
- Feline inappropriate urination
- Equine head shaking
Contraindications
- Assess antimuscarinic effects and patient-specific tolerance.
- Use cautiously with prostatic enlargement, urinary outflow obstruction, pyloroduodenal obstruction, severe heart failure or angle-closure glaucoma.
Interactions
- Other CNS depressants can increase sedation.
- Cyproheptadine can oppose the therapeutic effect of an SSRI.
Adverse effects
- Polyphagia and weight gain
- Hyperactivity in some cats
- Sedative or antimuscarinic effects
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Cyproheptadine 4 mg tablet | Tablet | 4 mg / tablet | PO |
| Cyproheptadine syrup 2 mg/5 mL Contains approximately 5% alcohol in the described formulation. | Oral Liquid | 2 mg / 5 mL | PO |
Monitoring and Administration
Monitor food intake and weight. Controlled veterinary evidence for appetite stimulation is limited; other agents have stronger support.
Feline experimental airway studies did not reduce eosinophilic inflammation. Do not infer that this replaces standard asthma treatment.
Equine pituitary disease use at 0.6–1.2 mg/kg is controversial and lacks a complete schedule in the passage; canine pituitary hyperadrenocorticism does not respond.
Syrup contains about 5% alcohol; protect from freezing.
If vomiting prevents oral cyproheptadine in serotonin syndrome, a crushed tablet/saline rectal preparation has been used; the rectal dose is not independently specified, so it is not copied automatically from oral dosing.
For feline asthma adjunctive use, response may take 4–7 days but CNS depression can appear within one day; this does not establish anti-inflammatory efficacy.
During prolonged feline treatment, periodically check BUN as well as appetite, weight and clinical response.