Periactin (cyproheptadine hydrochloride) is a versatile prescription medication with dual therapeutic applications, primarily recognized for its potent antihistaminic and appetite-stimulating properties. As a first-generation H1-receptor antagonist, it effectively mitigates allergic symptoms by blocking histamine release, while its serotonergic antagonism promotes hunger, making it a valuable option in clinical scenarios requiring weight gain support. Its well-established efficacy profile and decades of use position it as a reliable choice under appropriate medical supervision for both allergic conditions and cachexia-related concerns.

Features

• Active ingredient: Cyproheptadine hydrochloride
• Drug class: First-generation antihistamine, serotonin antagonist
• Available forms: 4 mg tablets, 2 mg/5 mL syrup
• Prescription status: Rx-only medication
• Mechanism: Dual H1-histamine and serotonin receptor blockade
• Onset of action: 30-60 minutes after administration
• Duration: 4-6 hours of therapeutic effect

Benefits

• Effectively reduces allergic symptoms including itching, hives, and rhinorrhea
• Promotes significant appetite stimulation in underweight patients
• Provides rapid relief from acute allergic reactions
• Demonstrates additional anti-serotonergic effects beneficial for certain conditions
• Offers flexible dosing options with both tablet and liquid formulations
• Established safety profile with extensive clinical history

Common use

Periactin is clinically indicated for the management of various allergic conditions including perennial and seasonal allergic rhinitis, allergic conjunctivitis, mild uncomplicated allergic skin manifestations of urticaria and angioedema, and amelioration of allergic reactions to blood or plasma. Additionally, it is prescribed off-label as an appetite stimulant in cases of weight loss related to chronic diseases, cachexia, or eating disorders. Some clinicians utilize its serotonin antagonism for managing serotonin syndrome or migraine prophylaxis, though these applications require specialized consideration.

Dosage and direction

For adults: The typical dosage for allergic conditions is 4 mg three times daily, not to exceed 0.5 mg/kg/day. For appetite stimulation, dosing typically begins at 4 mg three times daily and may be titrated based on response and tolerance. For elderly patients: Initiate with lower doses due to increased sensitivity to anticholinergic effects. Pediatric dosing: 0.25 mg/kg/day or 8 mg/m²/day divided into three or four doses, not to exceed 12 mg daily for children aged 2-6 years, or 16 mg daily for children aged 7-14 years. Administration should occur with food or milk to minimize gastrointestinal discomfort.

Precautions

Exercise caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, or bladder neck obstruction. Use with care in patients with hypertension, cardiovascular disease, or hyperthyroidism. May impair mental alertness; advise against operating machinery or driving until response is determined. Elderly patients may experience increased sensitivity to adverse effects including confusion, dizziness, and sedation. Monitor for signs of anticholinergic toxicity, especially in patients with reduced hepatic function.

Contraindications

Absolute contraindications include known hypersensitivity to cyproheptadine or other antihistamines of similar chemical structure, concomitant monoamine oxidase inhibitor therapy, neonatal or premature infants, and breastfeeding mothers. Additional contraindications include acute asthma attacks, lower respiratory tract symptoms, and patients with angle-closure glaucoma. Not recommended during pregnancy unless potential benefits outweigh risks (Pregnancy Category B).

Possible side effects

Common adverse reactions (≥1%) include drowsiness, dizziness, dry mouth/nose/throat, headache, appetite increase, weight gain, and gastrointestinal disturbances. Less frequent effects include confusion, restlessness, excitation, nervousness, insomnia, euphoria, blurred vision, diplopia, vertigo, tinnitus, palpitations, hypotension, thickening of bronchial secretions, urinary retention, and early menses. Rare but serious side effects include seizures, hematological abnormalities, and anaphylactic reactions.

Drug interaction

Significant interactions occur with CNS depressants (alcohol, barbiturates, opioids, sedatives) producing additive sedation. Monoamine oxidase inhibitors may prolong and intensify anticholinergic effects. Cyproheptadine may antagonize the effects of epinephrine and reverse the pressor effects. Concurrent use with anticholinergic agents may result in additive adverse effects. May interact with serotonergic drugs including SSRIs, SNRIs, and triptans. Monitor patients on hepatic enzyme-inducing or inhibiting drugs due to potential metabolic interactions.

Missed dose

If a dose is missed, administer as soon as remembered unless it is nearly time for the next scheduled dose. Do not double the dose to make up for the missed administration. Maintain regular dosing schedule; inconsistent dosing may reduce therapeutic efficacy particularly for appetite stimulation purposes. If multiple doses are missed, consult healthcare provider for dose readjustment rather than self-correcting with larger subsequent doses.

Overdose

Anticholinergic overdose manifestations may include CNS depression (sedation, coma) or stimulation (insomnia, hallucinations, convulsions), accompanied by dry mouth, fixed dilated pupils, flushing, gastrointestinal symptoms, and cardiovascular instability. In children, paradoxical excitation may occur. Treatment is supportive and symptomatic; activated charcoal may be administered if presented early. Physostigmine may be considered in severe cases with life-threatening symptoms under controlled settings. Maintain respiratory and cardiovascular support as needed.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) in original container with tight closure. Protect from light, moisture, and excessive heat. Keep syrup formulation from freezing. Dispense in light-resistant containers. Keep out of reach of children and pets. Do not use after expiration date printed on packaging. Properly discard any medication that appears discolored or shows signs of degradation.

Disclaimer

This information does not constitute medical advice and should not replace professional medical consultation. Periactin is a prescription medication requiring proper medical supervision. Individual response may vary based on patient-specific factors including age, renal/hepatic function, and concomitant medications. Healthcare providers should consider complete medical history before prescribing. Patients should report any adverse effects or concerns to their prescribing physician promptly.

Reviews

Clinical studies demonstrate Periactin’s efficacy in allergic conditions with 70-80% of patients experiencing significant symptom reduction. For appetite stimulation, multiple trials show mean weight gain of 2-4 kg over 4-8 weeks in cachexic patients. Patient reports frequently note improved quality of life through better allergy control and nutritional status. Some users report sedation as a limiting factor, while others appreciate the anxiolytic effects. Overall satisfaction rates range between 75-85% in post-marketing surveillance data when used according to appropriate indications and dosing guidelines.