Cyproheptadine

What is this medication for?

• Appetite stimulant (primary use); itching/asthma adjunct (marginal efficacy — not monotherapy for eosinophilic airway disease)
• Serotonin syndrome antidote (adjunct)
• Cushing's adjunct (antiserotonin) — <10% efficacy, largely abandoned
• Photic head-shaking, equine Cushing's

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Sedation (Main effect)
• Paradoxical hyperexcitability (Documented)
• Anticholinergic effects (dry mouth, urine retention, stomach/intestinal stasis) (Class)

Worth a phone call to your veterinarian

• Hemolytic low red blood cell counts reports (Rare feline reports)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Urinary/stomach/intestinal obstruction, severe CHF, narrow-angle glaucoma (anticholinergic load)

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • SSRIs/TCAs
  • Other anticholinergics/antihistamines
  • MAOIs

Storage and handling

Room temperature; generic tablets widely available.

Good to know

• The anti-serotonin Swiss-army knife: appetite stimulant by 5-HT2 blockade, serotonin-syndrome antidote in the same species — the antagonist partner to the SSRI/tramadol/MAOI overdose picture.
• Feline appetite ladder: mirtazapine > cyproheptadine > oxazepam — cyproheptadine is the cheap BID option with drowsiness as its tax.
• Not monotherapy for feline asthma/eosinophilic airway disease (Schooley) — marginal benefit at best.
• Paradoxical excitement in a sedative = classic feline antihistamine behavior.