The pandemic of Coronavirus Disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2), represents an unprecedented threat to health and the world economy. According to the scientific background and preliminary clinical trials, ozone therapy (OT) may help as complementary therapy in prophylaxis, treatment, and in the recovery of convalescents. During the COVID-19 pandemic, the number of registered clinical trials using OT on COVID-19 represented an increment of 36% compared to the total number of previously recorded clinical studies. At present, papers that report an intervention in COVID-19 patients total 25. Four trials have been done in prophylaxis, there are 3 manuscripts enrolled convalescents, and there is 1 meta-analysis. Manuscripts with outcomes, indexed in the MedLine database, represent 73%. The most widely used routes of administration for the intervention in COVID-19 patients are ozonated saline solution and major autohemotherapy. Preliminary results are encouraging, indicating that OT reduces inflammation indices, decreases the time of assisted respiration, decreases C-reactive protein, improves oxygen saturation, could decrease mortality, and makes polymerase chain reaction tests negative in shorter periods. When trained medical doctors follow the correct protocols and use certified devices, the improvements that have been reported allow the patients to recover more quickly. However, it is considered that larger clinical studies are needed.