Cancer is a major cause of mortality around the world, representing about 13% of deaths on the planet. Among the available cancer treatments, chemotherapy is most frequently utilized compared to other treatments such as surgery and radiotherapy. Many dietary antioxidants have proven to effectively prevent oxidative stress, which has been noted in many disease pathogeneses, including cancer. However, during chemotherapy or radiotherapy treatment of cancer patients, antioxidants are used as an adjuvant treatment. The use of a proof-based technique is advised in determining the supplements most suited to cancer patients. Though there are numerous opinions about the dangers and advantages of antioxidants, it is reasonable to conclude that side effects caused by antioxidants, for now, remain unclear for patients during cancer treatment, aside from smokers during radiotherapy. In this report, details of the effectiveness of antioxidants on cancer treatment aiding in the reduction of cancer therapy side effects are discussed.