Herbal Products and Dietary Supplements in Radiation Oncology: Evidence, Safety, and Practical Patient Counseling

Studies show that patients with cancer use herbal products more often than the general population. Lowering the risk of disease recurrence, symptom control, and improving quality of life are often the reasons cited for such use. However, a major concern is that few patients communicate with their oncology providers about such use. Although herbal products are perceived as natural and safe, they can lead to adverse effects and interact with prescription medications, including cancer treatments. Herb-drug interactions can render some treatments less effective or potentiate adverse effects of others. Therefore, patient-physician communication is critical to guide safe and appropriate use of herbal products and to minimize potential harm. The About Herbs website, developed and maintained by the Integrative Medicine and Wellness Service at Memorial Sloan Kettering Cancer Center, contains up-to-date, evidence-based information on purported uses, adverse effects and herb-drug interactions for 317 and growing number of herbs, vitamins, and other dietary supplements. The 5 most frequently accessed entries in 2025 were ashwagandha, Boswellia, active hexose correlated compound, reishi mushroom, and turmeric. In this article, we describe their uses and current evidence of effectiveness in oncology settings including radiation treatment.