What is the recommended dosage of cyproheptadine (antihistamine) for pediatric patients?

Cyproheptadine Dosing for Pediatric Patients

The recommended dosage of cyproheptadine for pediatric patients is 0.25 mg/kg/day, with specific age-based dosing guidelines: children 2-6 years should receive 2 mg two to three times daily (not exceeding 12 mg/day), and children 7-14 years should receive 4 mg two to three times daily (not exceeding 16 mg/day). 1

Age-Specific Dosing Guidelines

• For children aged 2-6 years:

  • Dose: 2 mg (½ tablet) two or three times daily
  • Maximum daily dose: 12 mg per day
  • Alternative calculation: 0.25 mg/kg/day or 8 mg per square meter of body surface area 1

• For children aged 7-14 years:

  • Dose: 4 mg (1 tablet) two or three times daily
  • Maximum daily dose: 16 mg per day 1

• For treatment of serotonin syndrome (specific indication):

  • Pediatric dosage: 0.25 mg/kg per day 2

Formulation and Administration

• Cyproheptadine is available as 4 mg tablets that can be divided for smaller doses 1
• No parenteral form is available, but tablets can be crushed and administered via nasogastric tube if needed 2

Safety Considerations

• Common side effects include drowsiness/sedation, which is the most frequently reported adverse effect in children 3
• Neurological symptoms are among the most common adverse effects reported (28.9% of pediatric adverse effect reports) 3
• Hepatic complications are uncommon to rare (estimated frequency 0.27 to 1.4/1000 patients) 3
• Other reported side effects include:
  • Excitation, hallucinations, ataxia, tachycardia, and muscle twitching 4
  • Occasional gastric pain, dry mucous membranes, mydriasis, and facial flushing 4

Special Considerations for Specific Indications

• When used for feeding intolerance in young children (under 3 years), starting doses have ranged from 0.069 to 0.825 mg/kg/day, with side effects such as sleepiness and constipation being rare 5
• For treatment of serotonin syndrome, cyproheptadine is preferred by most experts over other agents 2
• In autism spectrum disorder, cyproheptadine has been studied in combination with haloperidol, though this is not a primary indication 6

Monitoring and Precautions

• Symptoms of overdose appear rapidly after ingestion and generally do not last longer than 6-12 hours 4
• Caution is advised when prescribing cyproheptadine to children due to its considerable side effect profile 4
• Rare cases of aggression have been reported with cyproheptadine use in young children 7
• Liver function should be monitored as very rare cases of liver failure have been reported 3

Clinical Pearls

• Cyproheptadine is a first-generation antihistamine with antiserotonergic and anticholinergic effects 3
• While it has an orexigenic (appetite-stimulating) effect, this is not an FDA-approved indication in all countries 3
• The medication should be dosed according to the patient's size and response 1

Remember that dosage should always be individualized according to the needs and response of the patient, within the recommended ranges provided by the FDA guidelines.