Peritol

Selected form

Cyproheptadine

Method of action: Antiallergic, Antiserotonin

Treatment option: Allergic Reactions, Allergic Conjunctivitis, Anaphylaxis, Angioedema, Vasomotor Rhinitis, Dermatographia, Hives, Cold, Rhinitis, Pink Eye

Medically reviewed

Marina Burgos

Last updated on 10/01/2026

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Peritol

Property	Description
Active ingredient	Cyproheptadine hydrochloride
Form	Tablets, Oral Solution, Syrup
Pharmacological class	First-generation Antihistamine
General purpose	Alleviating symptoms of allergic reactions
Origin	Synthetic organic compound

What Type of Medicine is Peritol and What Does it Contain?

Peritol, a recognized trade name, is a pharmaceutical preparation containing Cyproheptadine hydrochloride, which is officially classified as a first-generation antihistamine. This compound, a synthetic organic compound, functions primarily as a potent histamine H₁ receptor antagonist. It is a single-component product formulated for oral administration, and is available to patients in solid preparations such as tablets and as a liquid oral solution or syrup.

The core of the medication is the Cyproheptadine entity itself. The final presentation includes either solid excipients for the tablets or an aqueous or syrup base for the liquid forms, which facilitates ease of use, particularly for the pediatric target audience. The Cyproheptadine 4 mg tablet was not withdrawn from sale for reasons of safety or effectiveness, allowing for generic versions to be approved.

What is the General Purpose of Peritol's Action?

The general purpose of Peritol is to provide symptomatic relief by influencing several key neurochemical pathways, specifically acting as a dual histamine H₁ receptor antagonist and a serotonin antagonist. The drug's mechanism against histamine works to alleviate the immediate physical symptoms associated with allergic reactions, such as generalized itching and localized swelling.

Its pharmacological distinction lies in its significant interaction with the serotonin system (5-HT₂ receptors), which is integral to its broader use profile compared to newer antihistamines. This characteristic dual antagonism is clinically recognized as beneficial for a wider range of conditions, extending beyond typical allergy treatment to include issues where the antiserotonergic activity is desired. This dual action contributes to overall symptomatic relief and is relevant to conditions involving specific vascular responses, often alongside an associated sedative effect.

Regulatory References

What side effects are possible with Peritol?

Possible side effects and safety information

The safety profile of Cyproheptadine is defined by reactions grouped into several System-Organ Classes (SOCs), as detailed in regulatory documents. The most frequently reported adverse reaction is drowsiness (somnolence), which is classified as Common in official labeling. This effect is often described as transient, with patients potentially no longer experiencing it after the initial three or four days of continuous administration.

Adverse effects are documented across various systems, including the Nervous System (dizziness, disturbed coordination, confusion, excitation), Gastrointestinal System (dry mouth, increased appetite, nausea, vomiting), and Hepatobiliary System.

Serious Adverse Reactions and Safety Constraints

The regulatory profile explicitly documents a range of serious adverse reactions, including:

Hepatic Failure and Jaundice (Hepatobiliary Disorders)
Blood Disorders such as Agranulocytosis and Hemolytic Anemia
Anaphylactic Shock and Convulsions

The medicine is officially subject to several contraindications. It is restricted from use in patients with conditions such as angle-closure glaucoma, stenosing peptic ulcer, and symptomatic prostatic hypertrophy. Caution is required in patients with pre-existing conditions like cardiovascular disease or hyperthyroidism.

Population-Specific Safety Considerations

Official labeling contains specific constraints for certain populations:

The medicine is Contraindicated in newborn or premature infants and in nursing mothers.
Safety and effectiveness are not established for pediatric patients under the age of two.
Older adults (geriatric patients) are noted to be more susceptible to adverse reactions such as dizziness, sedation, and hypotension.

Overdose and Emergency Response

Overdose Manifestations

Official regulatory documentation on Cyproheptadine (Peritol) overdosage outlines a serious clinical profile. Documented manifestations may involve the central nervous system (CNS), presenting as deep CNS depression or, paradoxically, as agitation, confusion, tremor, hallucinations, and seizures (convulsions). Signs consistent with anticholinergic toxicity are listed, including fixed and dilated pupils, dry mouth, and flushed skin. Cardiovascular complications may include tachycardia (rapid heartbeat) and irregular heart rhythm, alongside documented outcomes such as low blood pressure and urinary retention.

When to Seek Immediate Medical Help

The regulatory guidance mandates that immediate medical attention must be sought for any suspected overdose due to the potential for severe and life-threatening outcomes. Overdose carries the serious risk of progressing to respiratory arrest, cardiac arrest, and death. Emergency services should be contacted immediately if an individual collapses, experiences a seizure, has trouble breathing, or cannot be awakened.

Supportive Management and Population Notes

Management described in official documents is symptomatic and supportive. Procedures may include gastric lavage and the administration of activated charcoal to reduce drug exposure. Continuous monitoring of vital signs and an electrocardiogram (ECG) are often required. Infants and young children are explicitly noted in regulatory documents as a population with increased vulnerability, with a higher risk of severe outcomes including paradoxical excitation, convulsions, and CNS arrest.

Therapeutic Uses of Peritol

The medication's therapeutic application is relevant in clinical settings that involve acute or unstable symptom patterns. It generally plays a role in managing symptoms that create noticeable physiological strain and interference with daily functioning across three primary areas.

Main Therapeutic Areas

The medication may be commonly used to help with symptom clusters that may become intense or disruptive in conditions presenting with systemic or localized discomfort, including pruritus (generalized itching), hives (urticaria), allergic rhinitis, and conjunctivitis. A distinct application is relevant for easing symptoms of recurrent vascular head pain syndromes, such as migraines, and is applied in addressing appetite stimulation in specific clinical situations. The overall benefit contributes to maintaining a sense of stability when symptoms are more noticeable, relevant when supportive symptom management is appropriate.

“This symptomatic assistance contributes to improved comfort during periods of heightened symptoms.”

Key Application: Appetite Support

The medication is commonly used to help with appetite stimulation and may assist with maintaining functional stability related to nutritional intake in specific clinical situations where symptoms lead to functional strain.

Eligibility and Restrictions for Use

Eligibility Map: Who Can and Cannot Use Peritol — Official Regulatory Information

The eligibility profile for Peritol (Cyproheptadine hydrochloride) is strictly defined by regulatory documents, distinguishing between approved populations, populations requiring caution, and those who are expressly contraindicated.

Contraindicated Populations

Use is strictly prohibited for newborn or premature infants, nursing mothers, and elderly, debilitated patients. The medicine is also contraindicated in patients with specific comorbidities, including angle-closure glaucoma, stenosing peptic ulcer, bladder neck obstruction, and those receiving concurrent Monoamine Oxidase (MAO) Inhibitor therapy.

Age-Related Eligibility and Restrictions

Safety and effectiveness are established for use in adults and pediatric patients aged 2 years and older. However, use in children below the age of two has not been established. Geriatric patients (65 years and older) should use the medicine cautiously, and use is contraindicated if the patient is debilitated.

Restricted or Conditional Use

Regulatory labels require caution when administering Peritol to patients with a history of bronchial asthma, hyperthyroidism, or cardiovascular disease (including hypertension). For pregnant patients, the FDA classifies the drug as Category B; use is restricted to when it is clearly needed. Patients with renal impairment may require reduced doses and monitoring.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official regulatory profile for Cyproheptadine hydrochloride (e.g., Peritol) details specific pharmacodynamic interactions and absolute contraindications that structure its safe use. These restrictions are based on the additive effects when co-administered with certain drug classes.

Formal Interaction Restrictions

Interaction Type	Interacting Substance/Class	Official Constraint	Regulatory Basis
Contraindicated Combination	Monoamine Oxidase Inhibitors (MAOIs)	Co-administration is formally prohibited due to the risk of prolonged and intensified anticholinergic effects.	FDA / EMA SmPC
Additive CNS Effects	CNS Depressants (e.g., barbiturates, hypnotics, tranquilizers, opioid agonists)	Use is restricted due to additive effects, resulting in increased sedation and drowsiness.	Government Labels
Substance Interaction	Alcohol (Ethanol)	Formally documented to intensify nervous system side effects and impair alertness due to its CNS depressant properties.	Government Labels

Population-Specific Constraint

The medication is contraindicated for use in elderly or debilitated patients. This restriction is based on the heightened susceptibility of this population to the adverse outcomes resulting from the drug's interaction profile, particularly pronounced sedation and hypotension.

No mandatory timing separation requirements, such as administering doses X hours apart, are documented in official regulatory labeling for co-administration with other medicines.

Mechanism of Action

Peritol, which is cyproheptadine, functions primarily as a non-selective antagonist at multiple central and peripheral receptors. Its dominant mechanistic actions involve competitive antagonism at histamine H1 receptors and serotonin receptors, specifically the 5-HT2 A and 5-HT2 C subtypes, with the 5-HT2 A receptor being a primary target.

At the H1 receptor, its binding prevents endogenous histamine from activating the receptor. Similarly, in the central nervous system and peripheral tissues, its binding to the 5-HT2 A and 5-HT2 C receptors blocks the signaling cascade normally initiated by serotonin. This dual antagonistic action results in a broad systemic modulation. Furthermore, cyproheptadine exhibits ancillary antagonistic activity at muscarinic acetylcholine receptors and a non-specific inhibitory effect on calcium influx across cell membranes. The resulting physiological consequences include the blunting of histamine- and serotonin-mediated neuronal and cellular responses, leading to altered neurotransmitter balance and decreased smooth muscle contraction and vascular permeability.

Dosage and Administration Information

The administration of Cyproheptadine hydrochloride (Peritol) follows established administration principles, focusing on the route, precise dosing, and scheduling. The medication is a single-component product administered solely via the oral route, available as both 4 mg tablets and an oral solution or syrup (2 mg/5 mL). It may be taken with or without food.

Administration Principles and Dosing Regimens

Usage involves taking the total daily dose in divided amounts throughout the day, typically two or three times, as a single administration provides a therapeutic effect lasting approximately four to six hours. This divided schedule is essential for maintaining symptomatic control.

Population	Typical Starting Dose	Maximum Daily Dose (Do Not Exceed)
Adults	4 mg three times a day (TID)	32 mg
Children (7–14 years)	4 mg two or three times a day	16 mg
Children (2–6 years)	2 mg two or three times a day	12 mg

The dosage is always individualized based on patient needs and response, starting at a lower dose and adjusting as necessary. However, the stated maximum limits must be observed. For the liquid formulation, use a special calibrated measuring device to ensure dosage accuracy, as household spoons are imprecise. Dosing is not established for children under two years of age. Older adults are advised to start treatment at the low end of the dosing range due to potential increased sensitivity.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Peritol

This section provides an overview of the types of official research that have studied Cyproheptadine (Peritol), what was observed in these studies, and the aspects of the evidence that remain uncertain, according to scientific and regulatory sources.

Evidence for Use in Allergic Conditions

This section will summarize research that has studied the medicine in conditions characterized by fluctuating or episodic manifestations, such as generalized pruritus (itching), hives (urticaria), and allergic rhinitis. Official authorization for Cyproheptadine was evaluated based on historical clinical data and early controlled trials. This body of research was studied to explore outcomes related to physical discomfort during periods of heightened symptom activity.

Research describes patterns observed in how symptoms evolved in the observed populations, which included both adults and pediatric patients. However, the majority of the foundational research is older, which means its design may differ from the Randomized Controlled Trials (RCTs) conducted today. Comparative evidence against modern, second-generation antihistamines is lacking in recent high-quality trials, and the evidence provides limited insight into long-term outcomes for patients with chronic allergic conditions.

Evidence for Use in Appetite Stimulation and Support

Cyproheptadine was evaluated in research exploring outcomes related to appetite stimulation and support for weight gain, particularly in specific pediatric populations with feeding difficulties or outcomes related to undernourishment. This research primarily involved RCTs and systematic reviews.

Studies focused on physical measurements, such as changes in weight gain and changes in appetite. Some trials reported measurements of change in weight compared to a placebo during the short time intervals of the studies. Long-term effects are not fully established, as follow-up durations were limited (typically to a few months), and the maintenance of weight gain is not consistently tracked.

Research Gaps and Uncertainties

While the historical evidence is substantial for its use in allergic conditions, several research limitation frames are evident across the studies. Comparative evidence is lacking against current standard-of-care treatments for many indications. Sample sizes were modest in many of the key nutritional trials.

The evidence highlights what is known—and what is still uncertain. Findings were often mixed when comparing results, particularly regarding the use in vascular head pain. Long-term effects are not fully established across any of the main applications, meaning there is still a need for research exploring short-term symptom changes over extended periods.

Key Studies & References

Label: CYPROHEPTADINE HYDROCHLORIDE tablet - DailyMed - NIH

Frequently Asked Questions (FAQ)

Common questions about Peritol (FAQ)

Q: Are there any long-term risks associated with taking Peritol?

Official information indicates that long-term carcinogenic studies have not been performed with this medication. Research has primarily focused on short-term periods, and information on the long-term effects of continuous use remains limited in studies examining its therapeutic applications.

Q: Can I take Peritol if I am already taking an antidepressant?

Regulatory documents explicitly state that this medication is contraindicated (should not be used) if a patient is currently receiving Monoamine Oxidase Inhibitor (MAOI) therapy. The safety profile concerning interactions with other types of antidepressants, beyond MAOIs, is highly dependent on the specific drug, and this information is typically reviewed by a healthcare professional.

Q: What is the difference between Peritol and other antihistamines?

Peritol is classified as a first-generation antihistamine with a unique mechanism of action. According to official product information, it acts as both a histamine H1 receptor antagonist and a serotonin antagonist. This dual activity on two different signaling pathways is what distinguishes its pharmacological profile from many newer antihistamine drugs.

Q: Can Peritol affect my blood pressure?

Official adverse event reports mention effects such as hypotension (low blood pressure) and tachycardia (fast heart rate). Additionally, use with caution is advised for patients who have pre-existing high blood pressure (hypertension).

Q: What is the difference between Peritol tablets and syrup (if applicable)?

The drug is available in two main forms: a 4 mg tablet and an oral solution or syrup (e.g., 2 mg/5 mL). The liquid formulation is available as an alternative presentation for patients who may have difficulty swallowing tablets or for instances when a precise measurement of a smaller dose is necessary.

Q: Can Peritol cause a dry mouth or blurry vision?

According to official drug information, this medication may cause effects such as dry mouth, dizziness, or blurred vision. These types of effects are often associated with the drug's properties that affect certain nerve signals (known as anticholinergic activity).

Q: What organ processes Peritol in the body (e.g., liver or kidneys)?

Official pharmacokinetics data indicates that the drug is primarily processed (metabolized) by the liver. Following this process, the drug's byproducts (metabolites) are mostly eliminated in the urine and to a lesser extent through the feces.

Q: Is Peritol considered a prescription-only medicine?

In many regions, including the United States, the active ingredient Cyproheptadine is listed as a prescription-only medication. This means that a prescription or authorization from a licensed healthcare professional is typically required.

Q: What should I do if I notice a change in my vision while using Peritol?

The product information indicates that if a patient experiences vision problems (such as blurred vision), which are listed as serious side effects, the event should be reported to a healthcare professional.

Q: Does Peritol contain lactose or other common allergens?

Official labeling that lists inactive ingredients (excipients) confirms that the tablets contain lactose monohydrate. The presence of other common allergens depends on the specific formulation and may be verified on the official product labeling.

Q: What are the official regulatory approvals for Peritol?

The medication is officially indicated for a range of allergic conditions. These include symptoms of perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, and certain allergic skin manifestations such as hives (urticaria) and angioedema.

How should Peritol be stored and disposed of?

How to Store and Dispose of Peritol?

The storage and disposal instructions for Peritol (cyproheptadine hydrochloride) ensure product stability and safety, as outlined in regulatory documents.

Storage Conditions

Peritol must be stored at Controlled Room Temperature, which is generally defined as 20 C to 25 C (68 F to 77 F). The medication must be protected from freezing. Tablets should be kept in a well-closed container, and the syrup in a tight container. All forms of the medicine must be stored out of the sight and reach of children to prevent accidental ingestion.

Disposal Instructions

Unused or expired Peritol must not be thrown into household trash or wastewater. Disposal must follow local regulatory requirements for pharmaceutical waste. Returning the product to a pharmacy or using an official drug take-back program is the recommended method for safe disposal.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.