Periactin (cyproheptadine) is a first-generation H1 antihistamine. It blocks histamine at H1 receptors, which helps reduce classic allergy symptoms like sneezing, watery eyes, itching, and hives (urticaria). Because it also has anticholinergic effects, it can dry up secretions but may cause drowsiness and dry mouth. Clinicians often consider Periactin when antihistamines with less sedation haven’t provided adequate relief or when its additional properties are desirable for a specific patient’s needs.
Beyond allergies, Periactin’s unique anti-serotonin activity enables several off-label uses. It’s frequently used as an appetite stimulant to encourage weight gain in select patients (for example, those with poor appetite due to chronic illness) when diet, counseling, and other measures are insufficient—always with clinician oversight. Pediatric neurologists sometimes use cyproheptadine for migraine prevention in children. In acute hospital care, its serotonin-blocking action can be helpful as part of a physician-directed treatment plan for serotonin syndrome. These uses are off-label in the U.S., so discussion with a licensed clinician is essential to ensure benefits outweigh risks.
All dosing should be individualized by a clinician. For allergic conditions in adults, a typical starting regimen is 4 mg by mouth three times daily, with many patients responding to 12–20 mg/day in divided doses. Some adults may need up to 32 mg/day, but dose increases should be cautious due to sedation and anticholinergic effects. For children 7–14 years, 4 mg two to three times daily is common (maximum 16 mg/day). For children 2–6 years, 2 mg two to three times daily is typical (maximum 12 mg/day). Periactin is not recommended for infants. Always follow the dose your clinician prescribes.
For appetite stimulation and weight gain, clinicians generally start low and titrate slowly to balance benefit with tolerability. Many begin at 2 mg two or three times daily in younger/lower-weight patients or 4 mg twice daily in adolescents/adults, adjusting after several days to weeks. Some clinicians recommend taking a larger portion of the daily dose in the evening to reduce daytime drowsiness. Cycles of use (for example, several weeks on, then a break) are sometimes used to minimize tolerance and side effects; this should be guided by your clinician and individualized for your goals and response.
Migraine prophylaxis dosing in pediatrics often falls within the same ranges used for allergies, titrated carefully by weight and response. For any indication, take Periactin with or without food at roughly the same times each day. Do not exceed the prescribed maximum daily dose. If you experience troubling drowsiness, dry mouth, blurred vision, constipation, or mood/behavior changes, contact your clinician—dose adjustments, timing changes, or a gradual taper may be appropriate.
Sedation is common with Periactin, particularly when starting or increasing the dose. Avoid driving, operating machinery, or risky activities until you know how you respond. Alcohol and other central nervous system (CNS) depressants (like benzodiazepines, sleep aids, or opioids) can intensify drowsiness and should be avoided or minimized under medical advice. Because cyproheptadine has anticholinergic effects, it can cause dry mouth, constipation, urinary retention, and blurred vision—caution is warranted in older adults, who are particularly sensitive. Hydration, fiber, and saliva substitutes may help some side effects; ask your clinician for strategies tailored to you.
Use caution if you have asthma (drying of secretions can be problematic for some), cardiovascular disease (potential for tachycardia or hypotension), liver dysfunction, or glaucoma. Photosensitivity may occur; consider sun protection. If Periactin is being considered for appetite stimulation, ensure that reversible causes of low appetite (e.g., untreated depression, medications, thyroid issues, gastrointestinal problems) are addressed. For anyone with a history of disordered eating, Periactin should only be used within a comprehensive, clinician-supervised care plan. During pregnancy and breastfeeding, discuss risks and benefits carefully; safer alternatives may be preferred depending on the indication.
Periactin is contraindicated in newborn or premature infants; patients with narrow-angle (angle-closure) glaucoma; those with bladder neck obstruction, symptomatic prostatic hypertrophy, or urinary retention; and patients with stenosing peptic ulcer, pyloroduodenal obstruction, or acute asthma exacerbations. It is generally contraindicated with monoamine oxidase inhibitors (MAOIs) due to potentiation of anticholinergic and CNS effects. Hypersensitivity to cyproheptadine or any component is an absolute contraindication. Always provide your full medical and medication history to your clinician before starting therapy.
Common side effects include drowsiness, dizziness, dry mouth, blurred vision, constipation, and increased appetite/weight gain. Some people experience paradoxical CNS stimulation (especially children), restlessness, or irritability. Less common effects include nausea, vomiting, headache, confusion (notably in older adults), palpitations, hypotension, and photosensitivity. Very rare events such as hepatic dysfunction, blood dyscrasias, or severe hypersensitivity have been reported. Seek urgent care for signs of severe allergic reaction (facial swelling, difficulty breathing), severe confusion, hallucinations, inability to urinate, fainting, or seizure. If side effects are persistent or bothersome, contact your clinician—small dose changes or taking more at night often improves tolerability.
Avoid combining Periactin with MAO inhibitors (such as phenelzine, tranylcypromine, selegiline, linezolid, or methylene blue) due to risk of heightened anticholinergic/CNS effects. Alcohol, opioids, benzodiazepines, sedative-hypnotics, and other CNS depressants can add to drowsiness and impair coordination. Additive anticholinergic effects may occur with tricyclic antidepressants, antipsychotics, bladder antimuscarinics, antihistamines, and certain antiemetics. While cyproheptadine can be used by clinicians in serotonin syndrome, do not self-treat; interaction management with serotonergic drugs (SSRIs/SNRIs, triptans, tramadol, etc.) should be guided by a professional. Always review all prescription and over-the-counter drugs, supplements, and herbals with your clinician or pharmacist before starting Periactin.
If you miss a dose, take it when you remember unless it’s close to your next scheduled dose. If it’s near the next dose, skip the missed dose—do not double up. Return to your regular dosing schedule. If you miss doses frequently, consider setting reminders or discussing once-daily evening dosing with your clinician if appropriate for your indication and side-effect profile.
Overdose can cause pronounced anticholinergic toxicity: extreme drowsiness or paradoxical agitation, hallucinations, dilated pupils, flushed skin, fever, dry mucous membranes, rapid heart rate, high blood pressure or hypotension, tremor, seizures, and potentially life-threatening complications. Children are particularly vulnerable. If an overdose is suspected, call your local poison control center immediately (in the U.S., 1-800-222-1222) and seek emergency care. Do not induce vomiting unless directed by medical professionals. Supportive management in a medical setting is often required.
Store Periactin at room temperature (generally 20–25°C or 68–77°F), away from excess heat, moisture, and light. Keep in the original, tightly closed container. Do not use after the expiration date. Keep out of reach of children and pets.
Across public Reddit discussions, themes commonly include strong appetite increases within days to a couple of weeks, noticeable weight gain when paired with adequate calories and protein, and significant drowsiness—especially at the start or with daytime dosing. Many users describe shifting most of the dose to the evening to reduce daytime grogginess. Some note mood changes or irritability, while others report better sleep. A recurring topic is “tolerance”: a sense that appetite effects may lessen over time, leading some to use breaks or adjust dosing with clinician guidance. For migraines, several parents mention reduced frequency or intensity, balanced against sedation. Note: The above reflects aggregated themes from public conversations rather than verbatim quotes, and individual responses vary widely.
Patient reviews on consumer health sites like WebMD frequently highlight trade-offs: many report meaningful appetite stimulation and weight gain when supervised by a clinician, but sedation, dry mouth, and constipation are common drawbacks. Some users say the medication helped control hives or seasonal allergy symptoms that weren’t fully managed with non-drowsy antihistamines. Others caution that benefits can plateau, leading to dose adjustments or discontinuation. The overall takeaway from these self-reports is that cyproheptadine can be effective for select goals, but careful dosing, monitoring, and realistic expectations are crucial. This summary is a synthesis of typical patient feedback, not direct quotes, and should not substitute for medical advice.
In the United States, Periactin (cyproheptadine) is a prescription-only medication. It is not legal—or safe—to purchase true prescription antihistamines from websites that promise “no prescription” sales. Legitimate access requires evaluation by a licensed clinician who determines whether Periactin is appropriate for your condition, reviews your medications for interactions, and provides dosing and monitoring guidance. Many patients obtain Periactin through primary care, allergy, neurology, or pediatrics practices, or via reputable telehealth services that include a medical review and, if appropriate, an electronically issued prescription to a licensed pharmacy.
PATMOS EmergiClinic provides a structured, lawful pathway to explore Periactin by connecting you with licensed clinicians for a convenient evaluation. If Periactin is appropriate, a valid prescription can be issued and routed to a pharmacy—often without the need for an in-person visit. This approach preserves safety, meets regulatory requirements, and helps you avoid counterfeit or unsafe products. If Periactin isn’t right for you, a clinician can recommend alternatives and a comprehensive plan tailored to your goals, whether that’s allergy control, migraine prevention, or responsible appetite support.
Periactin is a first-generation antihistamine that blocks H1 histamine receptors to relieve allergy symptoms like itching, sneezing, and hives. It also antagonizes serotonin (5-HT2) and has anticholinergic effects, which explains its appetite-stimulating properties and use in certain migraine protocols.
It is approved for allergic conditions such as allergic rhinitis, urticaria (hives), and pruritus. Off-label, clinicians may use it to stimulate appetite in underweight patients, for pediatric migraine prevention, and as an adjunct in serotonin syndrome under specialist care.
Yes. By blocking serotonin and histamine, Periactin can increase appetite and promote weight gain in some people. It’s typically used short term with monitoring of weight, nutrition, and metabolic health.
Allergy relief usually starts within 30–60 minutes and lasts about 4–6 hours per dose. Appetite effects may emerge within several days to a few weeks and persist while the medication is continued.
A common adult regimen is 4 mg two to three times daily, with some patients titrated to a maximum of 32 mg/day if tolerated and needed. Start low, increase gradually, and follow your prescriber’s instructions.
Dosing is individualized by age and weight. Common ranges include 2–6 years: 2 mg two to three times daily (max 12 mg/day); 7–14 years: 4 mg two to three times daily (max 16 mg/day). Always use pediatric dosing under clinician guidance.
Drowsiness, dry mouth, dizziness, constipation, blurred vision, and increased appetite/weight gain are common. Less common but important effects include confusion (especially in older adults), urinary retention, fast heartbeat, and paradoxical excitation in children.
Avoid in newborns/premature infants, during use of MAO inhibitors or within 14 days of stopping an MAOI, in narrow-angle glaucoma, urinary retention, or pyloroduodenal obstruction. Use great caution in older adults, people with dementia, those with prostate enlargement, and those prone to anticholinergic side effects.
Use in pregnancy only if benefits clearly outweigh risks; discuss with your obstetric provider. Periactin may reduce milk production and can cause sedation in a nursing infant, so it’s generally not preferred during breastfeeding.
Yes. Alcohol, benzodiazepines, opioids, sleep aids, and other sedatives can increase drowsiness and impair coordination. MAO inhibitors are contraindicated. Other anticholinergics raise the risk of dry mouth, constipation, and urinary retention. It can blunt serotonergic effects of some antidepressants; consult your prescriber.
Not until you know how it affects you. Periactin commonly causes drowsiness and slowed reaction time; avoid driving or hazardous tasks if you feel sedated or dizzy.
Yes, it is used off-label, especially in children, for migraine prevention due to its antiserotonergic action. It is not a rescue medication for acute attacks; benefits typically appear after consistent daily use.
Follow your prescriber’s dose and schedule; many take it with meals or in the evening to leverage sedation at bedtime. Track weight, appetite, and dietary intake, and pair with a nutrition plan for healthy weight gain.
Take it when you remember unless it’s close to your next dose. If so, skip the missed dose. Do not double up.
Keep at room temperature in a dry place away from light and moisture, and out of reach of children and pets.
Both are first-generation antihistamines that work quickly but cause sedation. Periactin also blocks serotonin and is more associated with appetite stimulation and weight gain, whereas diphenhydramine is often used as a short-term sleep aid; neither is ideal for daily, long-term allergy control due to side effects.
Both relieve pruritus; hydroxyzine is commonly chosen for severe itching and can also help anxiety. Periactin may be preferred if appetite stimulation is desired, but it often causes daytime sedation; hydroxyzine can be similarly sedating.
Chlorpheniramine tends to be less sedating than many first-generation antihistamines, though it can still cause drowsiness. Periactin is typically more sedating and more anticholinergic, with a higher likelihood of increasing appetite and weight.
Both are sedating first-generation antihistamines with anticholinergic properties. Promethazine has stronger anti-nausea effects and carries specific safety concerns (including a boxed warning for respiratory depression in young children), while Periactin is more noted for appetite stimulation and migraine prevention uses.
Doxylamine is a go-to OTC sleep aid and a component of pregnancy nausea regimens (with vitamin B6). Periactin can cause sleepiness but isn’t primarily used for insomnia; it may be considered if appetite stimulation or migraine prevention is also needed.
Loratadine is a second-generation, minimally sedating antihistamine suited for daily, long-term allergy control. Periactin works but is more sedating and anticholinergic, making it less ideal for routine daytime use unless other clinical goals (like appetite) are present.
Cetirizine provides strong antihistamine effect with mild-to-moderate drowsiness in some people and is convenient once daily. Periactin is more sedating, requires multiple daily doses, and is often reserved for cases where appetite stimulation or specific off-label uses are intended.
Fexofenadine is essentially non-sedating at recommended doses and is better for daytime allergy control. Periactin is sedating and anticholinergic; it may be chosen for nighttime itching or appetite purposes, not for clear-headed daytime activities.
Both can help hives; levocetirizine is a potent, once-daily, low-sedation choice with good data for chronic urticaria. Periactin can help hives but is more likely to cause sedation and weight gain, so it’s usually not first-line for chronic daily use.
Azelastine delivers antihistamine directly to the nose with rapid relief and minimal systemic sedation. Periactin works systemically but causes more whole-body side effects; azelastine may be preferred for targeted nasal symptoms, especially in the daytime.
Ketotifen is an antihistamine with mast-cell stabilizing properties, widely used as an eye drop for allergic conjunctivitis and, in some regions, as an oral agent that can be sedating and increase appetite. Periactin is more strongly antiserotonergic and more commonly used for appetite stimulation and pediatric migraine prevention.
Meclizine is typically preferred for motion sickness due to its specific vestibular action and once-daily dosing. Periactin may help with nausea in some settings but is not a first-line motion sickness agent and is more often used for allergies, appetite, or migraine prevention.