Purpose: This study aimed to determine the efficacy and safety of Oncoxin as an antitumoral supplement, and to describe its mechanism of action. Methods: We performed this scoping review according to the recommendations of the Joanna Briggs Institute and included patients older than 18 years-old who have any kind of tumor and receive Oncoxin as a supplement. We focused on the efficacy in terms of antitumoral properties, quality of life and survival, safety in terms of adverse events, and the mechanism of action. We did not limit for language or setting. We searched MEDLINE (Pubmed), EMBASE (Scopus), LILACS, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to nowadays. Results: We found a promising increment of survival when taking Oncoxin as a supplementary treatment. Additionally, the quality of life increased in terms of Karnofsky and EORTC scales. Regarding the mechanism of action, studies suggest it modifies inflammatory mediators’ expression, as evidenced by the reduction of COX-2, IL-1β, IL-6, TNF-α, IL-1β, IL-12, and IFN-γ. Besides, it promotes an arrest in the progression of cells from G1 into S, along with an increase in p27 and a decrease in cyclin D1 and pRb. Conclusions: We found promising complementary effects of Oncoxin to the standard treatment of cancer patients in diverse scenarios, with putative robust mechanisms of action. In addition to clinically relevant impacts verified in clinical trials, as well as it decreases the levels of pro-inflammatory cytokines, it can also decrease cytokines with antitumor activity such as IFN-γ, which should be further explored in larger trials and the long term.