The rapid global spread and significant mortality associated with the coronavirus disease (COVID-19) caused by SARS-CoV-2 viral infection has spurred an urgent race to find effective treatments. Repurposing existing drugs is a particularly attractive approach as pharmacokinetic and safety data already exist, thus development can leapfrog straight to clinical trials of efficacy, generating results far more quickly than de novo drug development. This review summarizes the state of play for the principle drugs identified as candidates to be repurposed for treating COVID-19 grouped by broad mechanism of action: antiviral, immune enhancing, and anti-inflammatory or immunomodulatory. Patient selection, particularly with regard to disease stage, is likely to be key. To date only dexamethasone and remedesivir have been shown to be effective, but several other promising candidates are in trials.