Cyproheptadine (/ˌsaɪproʊˈhɛptədiːn/[4][5]), sold under the brand name Periactin or Peritol, is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties.

Starting at
| 4-(5H-dibenzo [a,d]cyclohepten-5-ylidene)-1-methylpiperidine hydrochloride |
| Trade names | Periactin |
| AHFS/Drugs.com | monograph |
| MedlinePlus | a682541 |
| Licence data | US Daily Med:link |
| Pregnancy category |
AU: A US: B (No risk in non-human studies) |
| Legal status |
AU: S3 (Pharmacist only) CA: OTC UK: OTC |
| Routes of administration |
Oral |
| Protein binding | 96 to 99% |
| Metabolism | Hepatic[1][2] |
| Biological half-life | 8.6 hours[3] |
| Excretion | Faecal (2-20%; 34% of this as unchanged drug) and renal (40%; none as unchanged drug)[1][2] |
| CAS Number | 129-03-3 969-33-5 (hydrochloride) |
| ATC code | R06AX02 |
| PubChem | CID: 2913 |
| IUPHAR/BPS | 277 |
| DrugBank | DB00434 |
| ChemSpider | 2810 |
| UNII | 2YHB6175DO |
| KEGG | D07765 |
| ChEBI | CHEBI:4046 |
| ChEMBL | CHEMBL516 |
| Formula | C21H21N |
| Molecular mass | 287.398 g/mol |
| SMILES[show] | |
| InChI[show] | |