A significant number of prostate cancer patients use complementary alternative medicines (CAMs) as an adjunct to their conventional treatment. Examples of CAMs that are frequently used by prostate cancer patients include green tea extract, lycopene, and pomegranate fruit extract. In many cases there is little if any clinical study-based evidence to support the efficacy of CAMs in this setting, and, importantly, some CAMs can cause serious adverse effects when taken a high doses and/or have significant drug interactions. The latter is an important consideration in this patient group as most patients are older and take multiple medications in addition to their anti-cancer drugs. This review summaries prostate cancer patient clinical trial data that is available for CAMs which are commonly used by prostate cancer patients, and provides dose, dose form, adverse effect, and drug interaction data. Providing evidence-based guidance regarding CAMs to prostate cancer patients can potentially improve patient outcomes, including the avoidance of adverse effects and drug interactions which impact drug efficacy.