Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties. It was patented in 1959 and came into medical use in 1961. Medical uses Cyproheptadine is used to treat allergic reactions (specifically hay fever). 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. 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. 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. Cyproheptadine is sometimes used off-label to improve akathisia in people on antipsychotic medications. It is used off-label to treat various dermatological conditions, including psychogenic itch drug-induced hyperhidrosis (excessive sweating), and prevention of blister formation for some people with epidermolysis bullosa simplex. 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. 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. Cyproheptadine has sedative effects and can be used to treat insomnia similarly to other centrally-acting antihistamines. The recommended dose for this use is 4 to 8 mg. Adverse effects Adverse effects include: 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