Tecovirimat, sold under the brand name Tpoxx among others,[6] is an antiviral medication with activity against orthopoxviruses such as smallpox and mpox.

[16] Antimicrobial resistance to tecovirimat was described in vitro in cowpox virus during treatment already in 2005, prior to licensure.

[17][19] Originally researched by the National Institute of Allergy and Infectious Diseases, the drug was owned by Viropharma and discovered in collaboration with scientists at the United States Army Medical Research Institute of Infectious Diseases.

[21][failed verification] As of 2008, it was permitted for phase II trials by the U.S. Food and Drug Administration (FDA).

[26][27] In November 2021, the Committee for Medicinal Products for Human Use of the European Medicines Agency recommended to grant SIGA Technologies Netherlands B.V a marketing authorization under exceptional circumstances for tecovirimat, intended to treat orthopoxvirus disease (smallpox, mpox, cowpox, and vaccinia complications) in adults and in children who weigh at least 13 kilograms (29 lb)[28] Tecovirimat was approved for medical use in the European Union in January 2022.

[5][29][30] In December 2021, Health Canada approved oral tecovirimat for the treatment of smallpox in people weighing at least 13 kilograms (29 lb).

[1][31] As of August 2022, Tpoxx was available in the US only through the Strategic National Stockpile as a Centers for Disease Control and Prevention investigational new drug.