Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties.

Clinical data
Trade namesPeriactin, others
License data
  • AU: A
  • US: B (No risk in non-human studies)
    Routes of
    ATC code
    Legal status
    Legal status
    Pharmacokinetic data
    Protein binding96 to 99%
    MetabolismHepatic.[2][3] Mostly CYP3A4 mediated.
    Elimination half-life8.6 hours[4]
    ExcretionFaecal (2-20%; 34% of this as unchanged drug) and renal (40%; none as unchanged drug)[2][3]
    CAS Number
    PubChem CID
    CompTox Dashboard (EPA)
    ECHA InfoCard100.004.482
    Chemical and physical data
    Molar mass287.398 g/mol g·mol−1
    3D model (JSmol)

    It was patented in 1959 and came into medical use in 1961.[5]

    Medical uses

    • Cyproheptadine is used to treat allergic reactions (specifically hay fever).[6] The evidence for its use for this purpose indicates its effectiveness but second generation antihistamines such as ketotifen and loratadine have shown equal results with fewer side effects.[7]
    • It is also used as a preventive treatment against migraine. In a 2013 study the frequency of migraine was dramatically reduced in patients within 7 to 10 days after starting treatment. The average frequency of migraine attacks in these patients before administration was 8.7 times per month, this was decreased to 3.1 times per month at 3 months after the start of treatment.[7][8] This use is on the label in the UK and some other countries.
    • It is also used off-label in the treatment of cyclical vomiting syndrome in infants; the only evidence for this use comes from retrospective studies.[9]
    • Cyproheptadine is sometimes used off-label to improve akathisia in people on antipsychotic medications.[10]
    • It used off-label to treat various dermatological conditions, including psychogenic itch[11] drug-induced hyperhidrosis (excessive sweating),[12] and prevention of blister formation for some people with epidermolysis bullosa simplex.[13]
    • One of the effects of the drug is increased appetite and weight gain, which has led to its use (off-label in the USA) for this purpose in children who are wasting as well as people with cystic fibrosis.[14][15] The evidence for the efficacy in light of other side effects is weak.[7][16]
    • It is also used off-label in the management of moderate to severe cases of serotonin syndrome, a complex of symptoms associated with the use of serotonergic drugs, such as selective serotonin reuptake inhibitors and monoamine oxidase inhibitors), and in cases of high levels of serotonin in the blood resulting from a serotonin-producing carcinoid tumor.[17][18]

    Adverse effects

    Adverse effects include:[2][3]

    • Sedation and sleepiness (often transient)
    • Dizziness
    • Disturbed coordination
    • Confusion
    • Restlessness
    • Excitation
    • Nervousness
    • Tremor
    • Irritability
    • Insomnia
    • Paresthesias
    • Neuritis
    • Convulsions
    • Euphoria
    • Hallucinations
    • Hysteria
    • Faintness
    • Allergic manifestation of rash and edema
    • Diaphoresis
    • Urticaria
    • Photosensitivity
    • Acute labyrinthitis
    • Diplopia (seeing double)
    • Vertigo
    • Tinnitus
    • Hypotension (low blood pressure)
    • Palpitation
    • Extrasystoles
    • Anaphylactic shock
    • Hemolytic anemia
    • Blood dyscrasias such as leukopenia, agranulocytosis and thrombocytopenia
    • Cholestasis
    • Hepatic (liver) side effects such as:
    - Hepatitis
    - Jaundice
    - Hepatic failure[19]
    - Hepatic function abnormality
    - Blurred vision
    - Constipation
    - Xerostomia (dry mouth)
    - Tachycardia (high heart rate)
    - Urinary retention
    - Difficulty passing urine
    - Nasal congestion
    - Nasal or throat dryness
    • Urinary frequency
    • Early menses
    • Thickening of bronchial secretions
    • Tightness of chest and wheezing
    • Fatigue
    • Chills
    • Headache
    • Increased appetite
    • Weight gain


    Gastric decontamination measures such as activated charcoal are sometimes recommended in cases of overdose. The symptoms are usually indicative of CNS depression (or conversely CNS stimulation in some) and excess anticholinergic side effects. The LD50 in mice is 123 mg/kg and 295 mg/kg in rats.[2][3]



    SiteKi (nM)ActionSpeciesRef
    Values are Ki (nM). The smaller the value,
    the more strongly the drug binds to the site.
    The ↓ and ↑ indicate antagonist and
    agonist type actions respectively.

    Cyproheptadine is a very potent antihistamine or antagonist of the H1 receptor. At higher concentrations, it also has anticholinergic, antiserotonergic, and antidopaminergic activities. Of the serotonin receptors, it is an especially potent antagonist of the 5-HT2 receptors, and this underlies its effectiveness in the treatment of serotonin syndrome.

    Cyproheptadine is known to be an antagonist or inverse agonist of all of the receptors listed in the adjacent table.[20]

    Cyproheptadine has weak antiandrogenic activity.[21]


    Cyproheptadine is well-absorbed following oral ingestion, with peak plasma levels occurring after 1 to 3 hours.[22] Its terminal half-life when taken orally is approximately 8 hours.[4]


    Cyproheptadine is a tricyclic benzocycloheptene and is closely related to pizotifen and ketotifen as well as to tricyclic antidepressants.


    Cyproheptadine was studied in one small trial as an adjunct in people with schizophrenia whose condition was stable and were on other medication; while attention and verbal fluency appeared to be improved, the study was too small to draw generalizations from.[23] It has also been studied as an adjuvant in two other trials in people with schizophrenia, around fifty people overall, and did not appear to have an effect.[24]

    There have been some trials to see if cyproheptadine could reduce sexual dysfunction caused by SSRI and antipsychotic medications.[25]

    Cyproheptadine has been studied for the treatment of posttraumatic stress disorder.[24]

    Veterinary use

    Cyproheptadine is used in cats as an appetite stimulant[26] and as an adjunct in the treatment of asthma.[27] Possible adverse effects include excitement and aggressive behavior.[28] The elimination half-life of cyproheptadine in cats is 12 hours.[27]

    Cyproheptadine is a second line treatment for pituitary pars intermedia dysfunction in horses.[29][30]


    1. "Cyproheptadine". Unabridged. Random House.
    2. "CYPROHEPTADINE HYDROCHLORIDE tablet [Boscogen, Inc.]" (PDF). DailyMed. Boscogen, Inc. November 2010. Retrieved 26 October 2013.
    3. "PRODUCT INFORMATION PERIACTIN® (cyproheptadine hydrochloride)" (PDF). Aspen Pharmacare Australia. Aspen Pharmacare Australia Pty Ltd. 17 November 2011. Archived from the original (PDF) on 29 October 2013. Retrieved 26 October 2013.
    4. Gunja N, Collins M, Graudins A (2004). "A comparison of the pharmacokinetics of oral and sublingual cyproheptadine". Journal of Toxicology. Clinical Toxicology. 42 (1): 79–83. doi:10.1081/clt-120028749. PMID 15083941.
    5. Fischer, Jnos; Ganellin, C. Robin (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 547. ISBN 9783527607495.
    6. MedlinePlus Drug Information: Cyproheptadine
    7. De Bruyne, P; Christiaens, T; Boussery, K; Mehuys, E; Van Winckel, M (January 2017). "Are antihistamines effective in children? A review of the evidence". Archives of Disease in Childhood. 102 (1): 56–60. doi:10.1136/archdischild-2015-310416. PMID 27335428.
    8. Saito, Y; Yamanaka, G; Shimomura, H; Shiraishi, K; Nakazawa, T; Kato, F; Shimizu-Motohashi, Y; Sasaki, M; Maegaki, Y (May 2017). "Reconsideration of the diagnosis and treatment of childhood migraine: A practical review of clinical experiences". Brain & Development. 39 (5): 386–394. doi:10.1016/j.braindev.2016.11.011. PMID 27993427.
    9. Salvatore, S; Barberi, S; Borrelli, O; Castellazzi, A; Di Mauro, D; Di Mauro, G; Doria, M; Francavilla, R; Landi, M; Martelli, A; Miniello, VL; Simeone, G; Verduci, E; Verga, C; Zanetti, MA; Staiano, A; SIPPS Working Group on, FGIDs. (16 July 2016). "Pharmacological interventions on early functional gastrointestinal disorders". Italian Journal of Pediatrics. 42 (1): 68. doi:10.1186/s13052-016-0272-5. PMC 4947301. PMID 27423188.
    10. Taylor, David; Paton, Carol; Kapur, Shitij (2015). The Maudsley Prescribing Guidelines in Psychiatry. John Wiley & Sons. p. 85. ISBN 9781118754573.
    11. Szepietowski, JC; Reszke, R (2016). Psychogenic Itch Management. Current Problems in Dermatology. 50. pp. 124–32. doi:10.1159/000446055. ISBN 978-3-318-05888-8. PMID 27578081.
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    13. Pfendner, Ellen G.; Bruckner, Anna L. (October 13, 2016). "Epidermolysis Bullosa Simplex". GeneReviews. PMID 20301543.
    14. Ciproheptadina, estimulante del apetito (Cyproheptadine, appetite stimulant)
    15. Bioplex NF
    16. Chinuck, R; Dewar, J; Baldwin, DR; Hendron, E (27 July 2014). "Appetite stimulants for people with cystic fibrosis". The Cochrane Database of Systematic Reviews (7): CD008190. doi:10.1002/14651858.CD008190.pub2. PMID 25064192.
    17. Rossi, S, ed. (2013). Australian Medicines Handbook (2013 ed.). Adelaide: The Australian Medicines Handbook Unit Trust. ISBN 978-0-9805790-9-3.
    18. Iqbal, MM; Basil, MJ; Kaplan, J; Iqbal, MT (November 2012). "Overview of serotonin syndrome". Annals of Clinical Psychiatry. 24 (4): 310–8. PMID 23145389.
    19. Chertoff, Jason (8 July 2014). "Cyproheptadine-Induced Acute Liver Failure". ACG Case Reports Journal. 1 (4): 212–213. doi:10.14309/crj.2014.56. PMC 4286888. PMID 25580444.
    20. Roth, BL; Driscol, J. "PDSP Ki Database". Psychoactive Drug Screening Program (PDSP). University of North Carolina at Chapel Hill and the United States National Institute of Mental Health. Retrieved 14 August 2017.
    21. Pucci E, Petraglia F (December 1997). "Treatment of androgen excess in females: yesterday, today and tomorrow". Gynecol. Endocrinol. 11 (6): 411–33. doi:10.3109/09513599709152569. PMID 9476091.
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    24. Dabaghzadeh, F; Khalili, H; Ghaeli, P; Dashti-Khavidaki, S (December 2012). "Potential benefits of cyproheptadine in HIV-positive patients under treatment with antiretroviral drugs including efavirenz". Expert Opinion on Pharmacotherapy. 13 (18): 2613–24. doi:10.1517/14656566.2012.742887. PMID 23140169.
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    27. Dowling PM (February 8, 2005). "Systemic Therapy of Airway Disease: Cyproheptadine". In Kahn CM, Line S, Aiello SE (eds.). The Merck Veterinary Manual (9th ed.). John Wiley & Sons. ISBN 978-0-911910-50-6. Retrieved on October 26, 2008.
    28. Dowling PM (February 8, 2005). "Drugs Affecting Appetite". In Kahn CM, Line S, Aiello SE (eds.). The Merck Veterinary Manual (9th ed.). John Wiley & Sons. ISBN 978-0-911910-50-6. Retrieved on October 26, 2008.
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