Antivirals are a class of small molecules that function as inhibitors of one or more stages of a virus life cycle. Because of similarities between different virus replication mechanisms, some antivirals can be repurposed against various viral infections. Currently, most of the available antiviral drugs tested against SARS-CoV-2 are small molecules previously developed against SARS-CoV-1, MERS-CoV, or other RNA and DNA viruses.