Cyproheptadine
PERIACTIN
What it isFirst-generation antihistamine with 5-HT2 antagonism; allergy, appetite stimulation and serotonin syndrome.
Why this oneIt is the agent used for serotonin syndrome, and the appetite effect is exploited deliberately.
What limits itSedation and anticholinergic burden. Weight gain is the point or the problem, depending on the patient.
FDA-approved for
- allergy (~1961)
Off-label
- appetite stimulation
- serotonin syndrome
- SSRI sexual dysfunction
FDA label
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Allergic conditions (antihistamine) | Pediatrics 2–6 yr | 2 mg BID–TID | 12 mg/day | |
| Allergic conditions (antihistamine) | Pediatrics 7–14 yr | 4 mg BID–TID | 16 mg/day | |
| Allergic conditions (antihistamine) | Adults | 4 mg TID | 4–20 mg/day (typical 12–16 mg) | 0.5 mg/kg/day (~32 mg) |
Renal Undefined
Hepatic Undefined
Instructions
- Individualize dose to patient response
Contraindications
- Newborn or premature infants
- Nursing mothers
- MAOIs (concurrently) because MAO inhibitors prolong and intensify the anticholinergic effects of antihistamines
- Angle-closure glaucoma
- Stenosing peptic ulcer
- Symptomatic prostatic hypertrophy
- Bladder neck obstruction
- Pyloroduodenal obstruction
- Elderly, debilitated patients
Adverse reactions
- Sedation, drowsiness, dizziness
- Dry mouth
- Increased appetite / weight gain
- Blurred vision
- Anticholinergic effects (urinary retention, constipation)
Pregnancy Category B — use only if clearly needed
Lactation Contraindicated in nursing mothers
NO BOXED WARNINGS
Principal riskSedation, anticholinergic burden and weight gain
Cost, est. cash$5–$150/month
Generic entry1982
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Cyproheptadine ballicule
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Memory aids: mascots and interaction avatars
used off-label to stimulate appetite
In actin' like a docile pet, it helps to dine on pet food
“mad as a hatter” → BBB-crossing antimuscarinic
crown resembling H1 blocking peg → antihistamine
