C Baker et al. J Pediatr Gastroenterol Nutr. 2026;82:1321–1324. Cyproheptadine: The secret sauce

Mechanism of action:

• A first-generation antihistamine with anti-cholinergic, anti-serotonergic, and local anesthesia properties; its precise mechanism of action is poorly understood.

Formulation/pharmocokinetics:

• Enteral tablet and syrup formulations appear to be well absorbed with peak serum levels 6–9 h after dosing in adults.² However, anecdotally in pediatrics, the side effect of somnolence is often felt much more quickly.

Uses (off-label):

• Promote weight gain: “There is ample literature to support success in varying populations, including mild to moderately undernourished toddler-aged children and children with cystic fibrosis.^4–6“
• Cyclic vomiting syndrome
• Functional abdominal pain and dyspeptic symptoms
• Post-operative Retching After Fundoplication

Dosing (by indication):

• “For cyclic vomiting syndrome prophylaxis, the recommended dose is 0.25–0.5 mg/kg/day divided every 8–24 h with a maximum dose of 12 mg a day.”
• “For appetite stimulation, the recommended dose is 0.25 mg/kg/day divided twice daily, with a maximum dose ranging from 12 to 32 mg depending on patient age.”
• “An effective dosing range for use in disorders of the gut–brain interaction (DGBIs) in pediatric patients (median age 9 years) of 0.13–0.2 mg/kg/day has been reported when used on average for 9 months, with a mean initial dose of 4.85 mg/day and final dose of 5.34 mg/day.¹“
• “A large, systematic review from France identified the median dose for all pediatric clinical indications to be 0.25 mg/kg/day…Many clinicians use once-daily dosing to improve adherence.”

Contraindications, Drug Interactions, and Complications:

• “Cyproheptadine is contraindicated in newborns and premature infants due to the potential for CNS depression and a lack of evidence in its safety and efficacy.”
• “Cyproheptadine has potential for multiple drug-drug interactions, and dose adjustments may be required with concomitant therapies.”
• “Recent publications suggest that up to 30% of patients will experience mild and self-limited side effects while taking cyproheptadine.⁸ The most common side effects are somnolence, increased appetite, weight gain, and behavior changes.^1, 8 Caution should be exercised in the use of cyproheptadine in children who are already considerably overweight…A rare side effect of adrenal insufficiency…has been documented in pediatric patients.”

My take: Because cyproheptadine is so useful for pediatric GI disorders, some of my colleagues have referred to it as “Vitamin P” (periactin). This review provides a lot of helpful data and guidance.

Related blog posts:

• Rome V Pediatric Upper Gastrointestinal Disorders of Gut-Brain Interaction (Part 2)
• 2025 Pediatric Cyclic Vomiting Syndrome Guidelines
• Ten-Year Trends in Pediatric Pharmacology for Gastroesophageal Reflux and Pediatric Feeding Disorders
• Dr. Neha Santucci: Management of DGBIs in the Post-Pandemic Era (Part 2)
• Dr. Praveen Goday: Tips on Managing Feeding Problems (Part 2)
• Cyproheptadine for dyspepsia

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