PURPOSE: This study aimed to assess the use of complementary and integrative medicine among cancer patients in Turkey for managing fatigue and to examine the moderating effect of disease duration on the relationship between fatigue levels and patients' attitudes toward complementary and integrative medicine. METHODS: A cross-sectional study was conducted with 231 cancer patients recruited from a chemotherapy center in western Turkey. Participants completed sociodemographic forms, the Holistic Complementary and Alternative Medicine Questionnaire, and the Visual Analog Scale for Fatigue. Data were analyzed using linear regression and moderation analysis. RESULTS: Among the participants, 38.5% reported using complementary and integrative medicine to manage fatigue, with biologically based treatments such as vitamin supplements and herbal tea being the most common. Regression analysis showed that younger age (p <
0.05), longer disease duration (p = 0.005), absence of complementary and integrative medicine-related complications (p <
0.001), and higher fatigue levels (p <
0.001) were significant predictors of positive attitudes toward complementary and integrative medicine. Additionally, disease duration moderated the relationship between fatigue levels and attitudes toward complementary and integrative medicine, with longer disease duration strengthening the association (B = - 0.269, SE = 0.078, p = 0.001). CONCLUSION: The findings suggest that fatigue and prolonged disease duration significantly influence cancer patients' attitudes toward complementary and integrative medicine. Given the increasing use of complementary and integrative medicine, healthcare professionals should provide evidence-based guidance to ensure its safe and effective use. Future research should explore the long-term effects of complementary and integrative medicine on cancer-related fatigue. RELEVANCE TO CLINICAL PRACTICE: This study highlights the importance of addressing cancer-related fatigue and recognizing the growing use of complementary and integrative medicine among cancer patients. PATIENT OR PUBLIC CONTRIBUTION: Patients were invited to complete questionnaires. Investigators explained the study's objectives and content and addressed any concerns raised during data collection.