Periactin (cyproheptadine hydrochloride) is a versatile prescription medication with dual therapeutic applications. Primarily recognized as a potent antihistamine, it effectively manages allergic conditions by blocking histamine receptors, thereby reducing symptoms like itching, sneezing, and urticaria. Additionally, it is widely prescribed off-label to stimulate appetite and promote healthy weight gain in both pediatric and adult populations, owing to its serotonergic antagonism. This comprehensive guide details its pharmacological profile, appropriate usage, and essential safety information for healthcare professionals and informed patients.

Features

• Active ingredient: Cyproheptadine hydrochloride
• Available formulations: 4 mg tablets and syrup (2 mg/5 mL)
• Pharmacological class: First-generation antihistamine (H1-receptor antagonist)
• Additional mechanisms: Serotonin (5-HT2) antagonist, mild anticholinergic properties
• Prescription status: Rx-only medication
• Half-life: Approximately 8–9 hours in adults

Benefits

• Effectively reduces histamine-mediated allergic reactions including seasonal allergies, chronic urticaria, and angioedema
• Promotes significant appetite stimulation through serotonin pathway modulation, supporting weight restoration
• Provides relief from pruritus associated with various dermatological conditions
• May help manage serotonin syndrome in emergency situations due to anti-serotonergic activity
• Demonstrates efficacy in preventing migraine headaches in certain patient populations
• Offers flexible dosing with both oral tablet and liquid formulations for varied patient needs

Common use

Periactin is clinically indicated for the management of allergic conditions including perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, mild uncomplicated allergic skin manifestations of urticaria and angioedema, and amelioration of allergic reactions to blood or plasma. Beyond its labeled indications, it is extensively used off-label for appetite stimulation in cases of malnutrition, cachexia associated with chronic diseases, failure to thrive in children, and eating disorders. Some neurologists also prescribe it for migraine prophylaxis and for the management of serotonin syndrome.

Dosage and direction

Adults: The typical dosage for allergic conditions is 4 mg three times daily, not to exceed 0.5 mg/kg/day. For appetite stimulation,起始剂量通常为4 mg daily, gradually titrated upward based on response and tolerance. Pediatric patients (2–6 years): 2 mg two or three times daily, not to exceed 12 mg in 24 hours. Pediatric patients (7–14 years): 4 mg two or three times daily, not to exceed 16 mg in 24 hours. Administration with food may minimize potential gastrointestinal upset. Dosage should be individualized based on therapeutic response and emergence of side effects.

Precautions

Patients should be cautioned about potential drowsiness and advised to avoid driving or operating machinery until their response is known. Use with caution in elderly patients due to increased susceptibility to dizziness, sedation, and anticholinergic effects. Those with hypertension, cardiovascular disease, hyperthyroidism, increased intraocular pressure, or prostatic hypertrophy require careful monitoring. May cause excitability in pediatric patients. Abrupt discontinuation after prolonged use should be avoided.

Contraindications

Periactin is contraindicated in patients with known hypersensitivity to cyproheptadine or other antihistamines of similar chemical structure. Should not be used in neonates or premature infants. Contraindicated in patients with narrow-angle glaucoma, bladder neck obstruction, stenosing peptic ulcer, pyloroduodenal obstruction, and symptomatic prostatic hypertrophy. Not recommended for use during asthma attacks. Concurrent use with monoamine oxidase inhibitors (MAOIs) is contraindicated.

Possible side effect

Common adverse reactions include drowsiness, dizziness, dry mouth/nose/throat, headache, and increased appetite. Less frequently reported effects include nausea, abdominal upset, restlessness, excitation (especially in children), blurred vision, diplopia, hypotension, palpitations, and photosensitivity. Rare but serious side effects may include seizures, hematological abnormalities, and anaphylactic reactions. Anticholinergic effects may include urinary retention and constipation.

Drug interaction

Periaptin may potentiate CNS depression when used with alcohol, barbiturates, hypnotics, anxiolytics, or other sedating medications. MAO inhibitors prolong and intensify anticholinergic effects. May counteract the effects of epinephrine. Serotonergic drugs (SSRIs, SNRIs, triptans) may interact through pharmacodynamic opposition. Anticholinergic drugs may produce additive effects.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. In that case, skip the missed dose and resume the regular dosing schedule. Do not double doses to make up for a missed dose.

Overdose

Symptoms may range from CNS depression (sedation, coma, respiratory depression) to paradoxical CNS stimulation (hallucinations, convulsions). Anticholinergic effects include dilated pupils, flushed face, hyperthermia, and gastrointestinal symptoms. Treatment is supportive and symptomatic. There is no specific antidote. Hemodialysis is not effective. Physostigmine may be considered in severe cases under careful monitoring.

Storage

Store at controlled room temperature (20°–25°C or 68°–77°F) in a tight, light-resistant container. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging. The syrup formulation should not be frozen.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Periactin is a prescription medication that should be used only under the supervision of a qualified healthcare professional. Individual response to medication may vary. Always consult with your physician for proper diagnosis and treatment recommendations. Do not initiate or discontinue medication without professional guidance.

Reviews

Clinical studies demonstrate Periactin’s efficacy in allergy management with 70-80% of patients experiencing significant symptom reduction. In appetite stimulation studies, weight gain of 1-2 kg per month has been observed in underweight patients. Patient reviews frequently note improved quality of life through better allergy control and successful weight restoration, though many report sedation as a significant side effect. Healthcare providers appreciate its dual functionality but emphasize careful patient selection and monitoring due to its side effect profile.