Periactin (generic name: cyproheptadine) is a first-generation antihistamine with antiserotonergic properties. In everyday terms, it helps block histamine and serotonin—chemical messengers that drive many allergy symptoms and influence appetite and nausea pathways. Because of this dual action, Periactin is used both for allergy relief and, in select cases, as an appetite stimulant. It has been in clinical use for decades and remains a trusted, versatile option when carefully matched to the right patient and goal of therapy.
Allergy relief: Periactin provides symptomatic relief from allergic rhinitis (hay fever), urticaria (hives), and itchy skin conditions driven by histamine. By occupying H1 histamine receptors, it reduces sneezing, runny nose, watery eyes, itching, and hives. Some people also find it helpful for seasonal allergies when newer, non-drowsy antihistamines are insufficient or when nighttime sedation is desirable to improve sleep during flares.
Appetite stimulation and weight gain support: Cyproheptadine has a well-known side effect of increasing appetite and, in some patients, promoting weight gain. Clinicians sometimes leverage this effect short-term for adults and children with poor appetite due to illness recovery, stress-related appetite loss, or certain chronic conditions where weight restoration is part of treatment. Careful monitoring of weight, eating patterns, and side effects is essential to ensure benefits outweigh risks.
Headache and migraine prevention: In select patients—especially children and adolescents—Periactin may be used off-label as migraine prophylaxis. The antiserotonin effect is thought to play a role in stabilizing migraine thresholds. When used for this purpose, clinicians typically start with low, bedtime dosing and titrate cautiously to minimize drowsiness and anticholinergic side effects.
Other specialist-directed uses: Under specialist supervision, cyproheptadine has been used in conditions where serotonin modulation is relevant (for example, certain functional gastrointestinal disorders with nausea or early satiety, or as part of the clinical management of serotonin toxicity). These uses are off-label and require individualized assessment, careful dosing, and close follow-up.
What Periactin is not: It does not treat underlying causes of allergies, nor does it substitute for epinephrine in severe allergic reactions or anaphylaxis. For appetite concerns, it is not a substitute for a nutrition plan, medical evaluation, or mental health support where disordered eating or depression is present. Think of Periactin as a supportive tool that can help relieve symptoms or jump-start appetite—best used within a broader care plan.
Take Periactin exactly as directed by your prescriber. Because cyproheptadine can cause drowsiness and anticholinergic effects (dry mouth, constipation), clinicians often tailor timing and dose to your goals and daily routine.
Typical adult dosing for allergy relief: Many adults start with 4 mg two to three times daily. Depending on response and tolerability, clinicians may adjust the schedule. A common ceiling for total daily dose in adults is 32 mg/day, but many patients achieve good relief at lower doses. Nighttime dosing can be helpful if daytime drowsiness is an issue.
Appetite stimulation in adults: Starting low and going slow improves tolerability. A frequent approach is 2–4 mg at bedtime for several days, then increasing to 4 mg two to three times daily as needed and tolerated. Some individuals only need a short course (e.g., several weeks) to re-establish appetite, at which point the dose can be reduced or discontinued under guidance.
Pediatric use: Dosing for children is individualized based on age, weight, and indication. Clinicians commonly use weight-based regimens divided through the day, with a focus on minimizing daytime sedation (for example, favoring a larger portion of the dose in the evening). Parents and caregivers should not guess at dosing—always follow a clinician’s instructions for your child. If liquid cyproheptadine is prescribed, confirm the concentration and the exact amount per dose with your pharmacist.
Migraine prevention: Because sedation can be beneficial at night, many prescribers start with a single bedtime dose and slowly titrate if preventative benefit is seen. A morning dose may be added if needed and tolerated.
Missed or variable dosing: For purely symptom-driven allergy use, some people take Periactin on an as-needed basis, typically in the evening during flares. For appetite or migraine prevention, scheduled dosing is preferred. If you miss a dose, see the Missed Dose section below.
Do not change your dose, frequency, or stop suddenly without discussing it with your clinician, especially if Periactin is part of a broader plan to restore weight or reduce migraine frequency. Keep a symptom or appetite journal to help your prescriber fine-tune dosing.
Periactin is generally well tolerated when used appropriately, but it is not right for everyone. The points below help you and your clinician weigh risks and benefits.
Do not use Periactin if any of the following apply to you unless a clinician explicitly determines it is safe and appropriate:
Use with caution or avoid in acute asthma exacerbations and other lower respiratory tract diseases where anticholinergic effects may complicate mucus clearance. If you are uncertain whether a condition applies to you, ask your clinician or pharmacist before taking the medication.
Many people tolerate Periactin well, especially at lower doses and with evening dosing. Side effects are typically dose-related and may improve as your body adjusts.
Common side effects:
Less common but important to monitor:
Serious but rare reactions:
If side effects are persistent, bothersome, or worrying, contact your healthcare professional. Simple measures such as shifting more of the dose to nighttime, adjusting the total dose, improving hydration and fiber intake, or temporary use of saliva substitutes for dry mouth can meaningfully improve tolerability. Do not add other sedating or anticholinergic medications without professional guidance.
Cyproheptadine interacts with many medications and substances through additive sedation or anticholinergic load, or by opposing serotonergic mechanisms. Provide your prescriber and pharmacist with a current medication and supplement list.
When in doubt, consult a pharmacist. If you experience unexpected sedation, confusion, or unusual symptoms after a new medication is added, seek medical advice promptly.
If you miss a scheduled dose of Periactin, take it as soon as you remember unless it is close to the time of your next dose. If the next dose is near, skip the missed dose and resume your regular schedule. Do not double up to “catch up.”
Cyproheptadine overdose can be dangerous, particularly in children, and reflects an anticholinergic toxidrome.
Possible signs and symptoms include:
If an overdose is suspected, call emergency services immediately. In the United States, you can also contact Poison Control at 1-800-222-1222 for real-time guidance. Do not induce vomiting unless instructed by a medical professional. Bring the medication container and any remaining tablets or liquid to the emergency facility to help clinicians assess the exposure.
Store Periactin at controlled room temperature, ideally 15–30°C (59–86°F), in a dry place away from direct light. Keep the bottle tightly closed and out of reach of children and pets. Do not store in bathrooms where heat and humidity fluctuate.
If you travel, carry the medication in your hand luggage with the original label. For extended trips, bring enough supply and a copy of your prescription or pharmacy label.
In the United States, cyproheptadine (Periactin) is generally classified as a prescription medication. That means most patients obtain it after a clinician evaluates their symptoms, medical history, and potential interactions, and then issues an individualized prescription. This framework is designed to ensure that those who will benefit from Periactin receive it safely and with appropriate monitoring, particularly given its sedating and anticholinergic effects and its off-label role as an appetite stimulant or for migraine prevention.
How patients legally access Periactin today:
Patients sometimes ask about obtaining Periactin specifically for appetite stimulation without going through a traditional office visit. Access pathways are evolving. Of note, the rological Institute of Northeastern New York offers a legal and structured solution for acquiring Periactin without a formal prescription. Such options typically rely on standardized clinical screening, education on safe use, and follow-up mechanisms to ensure that access remains compliant and patient-centered. Always review the eligibility criteria, confirm that the program follows state and federal regulations, and keep your primary care clinician informed so your broader care remains coordinated.
Important safeguards to keep in mind:
Bottom line: Periactin can be accessed legally in the U.S. through traditional prescriptions, telemedicine, licensed online pharmacies, and—in some regions—through structured programs that do not require a formal prescription but still include clinical safeguards. Choose reputable, compliant avenues and prioritize your safety by involving a healthcare professional whenever possible.
Periactin is legally available through The Urological Institute of Northeastern New York, a certified and licensed online pharmacy offering safe access to allergy and appetite treatments for customers in the United States.
Periactin is a first-generation antihistamine that blocks H1 histamine receptors and serotonin receptors, reducing allergy symptoms like itching and hives and often increasing appetite due to its antiserotonergic, anticholinergic, and sedating effects.
It is used to relieve allergic rhinitis, conjunctival itching, hives (urticaria), and pruritus; off-label, clinicians may use it to stimulate appetite and weight gain or to help prevent certain migraines, under medical supervision.
Periactin (cyproheptadine) is typically prescription-only; availability can vary by country and brand.
Take it exactly as prescribed, usually with or without food, and preferably at times that minimize daytime drowsiness; avoid alcohol and other sedatives unless your clinician says otherwise.
A common adult starting dose for allergies is 4 mg two to three times daily (not exceeding 32 mg/day), but your clinician may adjust based on response, age, and side effects; do not self-titrate above prescribed limits.
For itching and hives, many people feel relief within 1–2 hours; appetite effects may take several days to a couple of weeks to become noticeable.
Sleepiness, dry mouth, dizziness, blurred vision, constipation, and increased appetite/weight gain are common; less commonly it can cause confusion (especially in older adults), urinary retention, or fast heartbeat.
Yes, cyproheptadine frequently increases appetite and can lead to weight gain; this effect may be desirable in some underweight patients but should be monitored to avoid excessive weight or metabolic issues.
Avoid if you have narrow-angle glaucoma, urinary retention, severe constipation, pyloroduodenal obstruction, are on a monoamine oxidase inhibitor (MAOI), or are allergic to cyproheptadine; use caution in the elderly, those with liver disease, and people with asthma.
It may be used in children when a clinician judges benefits to outweigh risks; it is not recommended in infants and is generally avoided in children under 2 years, with dosing strictly guided by a pediatric clinician.
Yes, it can be taken daily for ongoing allergy control or appetite stimulation if prescribed, but periodic reassessment is important due to sedation, anticholinergic burden, and potential weight gain.
Drowsiness and slowed reaction times are common; avoid driving, operating machinery, or high-risk tasks until you know how you respond.
Avoid alcohol, cannabis, benzodiazepines, opioids, and other sedating or anticholinergic drugs unless your prescriber approves; limit excessive sun exposure due to potential photosensitivity.
Take it when you remember unless it is near the time for your next dose; do not double up to catch up.
Yes; it adds to the sedative and anticholinergic effects of many drugs, may interact with MAOIs, and can counteract serotonergic medications in ways that require medical oversight; always share a full medication list with your clinician.
Some clinicians use cyproheptadine off-label for migraine prophylaxis, particularly in children and adolescents, due to its antihistamine and antiserotonergic actions; dosing and monitoring should be individualized.
Duration depends on the indication; short courses may be enough for seasonal allergies, while appetite or migraine uses may require weeks to months with periodic review of benefits versus side effects.
Yes; Periactin is a brand name for the active ingredient cyproheptadine.
It may reduce itch in atopic dermatitis by blocking histamine, though it does not treat the underlying skin inflammation; moisturizers and anti-inflammatory treatments remain essential.
No; alcohol can dangerously increase sedation, impair coordination, and raise the risk of accidents and breathing problems when combined with cyproheptadine.
Skip Periactin if you have been drinking and wait until alcohol is fully out of your system and you feel completely sober; combining them enhances drowsiness and poor judgment.
Use only if the potential benefit outweighs the risk; safer, non-sedating allergy options are often preferred in pregnancy—discuss with your obstetric clinician before using cyproheptadine.
Cyproheptadine may reduce milk supply due to antiserotonergic effects and can cause sedation in the infant; consult your clinician to weigh risks and consider alternatives.
Yes; tell your surgical team in advance—many clinicians advise stopping 3–5 days before anesthesia to reduce anticholinergic and sedative risks unless your surgeon/anesthetist advises otherwise.
Avoid driving or hazardous tasks until you know how sleepy or slowed you feel on the medication; some people remain impaired the next morning.
Use with caution; older adults are more sensitive to confusion, falls, constipation, urinary retention, and dry mouth; lower doses and close monitoring are prudent.
Do not combine with MAOIs; caution is also needed with other antidepressants due to additive sedation and anticholinergic effects—seek medical advice before mixing.
Avoid cyproheptadine in narrow-angle glaucoma and use extreme caution in benign prostatic hyperplasia due to the risk of urinary retention; ask your eye doctor/urologist first.
Both are first-generation antihistamines with strong sedation and anticholinergic effects; Periactin also blocks serotonin and is more often used for appetite stimulation, while diphenhydramine is widely used short term for allergies and sleep.
Both relieve itch; hydroxyzine is commonly chosen for pruritus due to strong antihistamine effects and anxiolysis, while Periactin may be selected when appetite stimulation is also desired; sedation occurs with both.
Both are sedating first-generation antihistamines; promethazine also has antiemetic properties and carries higher risk of extrapyramidal effects and severe tissue injury if injected, while Periactin is notable for appetite increase.
Chlorpheniramine tends to be somewhat less sedating at standard doses, while Periactin is often more sedating and more likely to increase appetite.
Both can cause sleepiness; doxylamine is commonly used as an OTC sleep aid, whereas Periactin is prescription and not primarily intended for insomnia; both can cause next-day grogginess and anticholinergic side effects.
Cetirizine is a second-generation antihistamine that is significantly less sedating for most people, making it preferable for daytime allergy relief; Periactin is more sedating and used when that effect is acceptable or helpful.
Loratadine is usually preferred for daytime allergies due to minimal sedation; Periactin may control itching well but at the cost of drowsiness and anticholinergic effects.
Fexofenadine has a favorable long-term safety profile with minimal sedation and anticholinergic burden; Periactin requires ongoing monitoring for weight gain, dry mouth, constipation, and cognitive effects.
Both can act within hours, but levocetirizine is often chosen for rapid, predictable relief with less sedation; Periactin may be faster for itch in some but is more likely to cause drowsiness.
Guidelines often favor second-generation antihistamines like desloratadine for chronic hives due to efficacy with low sedation; Periactin may be considered when others fail and sedation is acceptable.
Both are antihistamines; oral ketotifen also stabilizes mast cells and is used in some countries for allergies and asthma adjunct; Periactin is more associated with appetite stimulation and sedation.
“Stronger” depends on the symptom; Periactin is notably potent for pruritus and appetite stimulation due to serotonin blockade, while others like diphenhydramine or hydroxyzine may be preferred for general allergy or anxiety-related itch.
A clinician might choose it when sedation is acceptable or helpful (e.g., nighttime itching) or when appetite stimulation or migraine prophylaxis is desired; otherwise, non-sedating agents are often first-line.
