Tecovirimat (also known as TPOXX or ST-246) is a small-molecule antiviral drug with the chemical name rel-N-[(3aR,4R,4aR,5aS,6S,6aS)-3,3a,4,4a,5,5a,6,6a-octahydro-1,3-dioxo-4,6-ethenocycloprop[f]isoindol-2(1H)-yl]-4-(trifluoromethyl)benzamide. It is a white to off-white crystalline powder. Tecovirimat is specifically designed as an inhibitor of the orthopoxvirus VP37 envelope wrapping protein. This mechanism of action prevents the formation of extracellular enveloped virions, which are essential for cell-to-cell and long-range dissemination of the virus within a host. Its primary and most significant application is for the treatment of human smallpox disease caused by variola virus. It is also indicated for the treatment of complications from vaccinia virus infection following vaccination against smallpox. Due to its targeted activity against orthopoxviruses, it represents a critical medical countermeasure for potential bioterrorism threats involving smallpox. The drug was approved by the U.S. FDA in 2018 and is stockpiled by governments for emergency use. It is available in both oral capsule and intravenous formulations.