Objectives Chemotherapy-related side effects (CRSE) are among the most distressing events cancer patients face. Some patients seek complementary and alternative medicines (CAM), increasing the risk of undesirable drug- CAM interactions. This study aims to identify the prevalence and type of CAM used for CRSE among cancer patients and patient’s disclosure of CAM use to their prescribers. Methods This was a questionnaire-based, cross-sectional study. Data was collected from cancer patients attending to three departments: surgical, medical and gynaecology at a local hospital in Malaysia. Ethical approval was obtained from the Medical Research Ethics Committee, Ministry of Health, Malaysia. Results A total of 273 patients were recruited. Prevalence of CAM used for CRSE management was 166 (60.8%). Of the CAM users, 144 (86.7%) were female, 102 (61.4%) were employed and 123 (74.1%) were married. Breast cancer patients were found to be the highest users of CAM (n=76; 45.8%). The top three CAM used by patients in managing CRSE were dietary supplements (n=166; 100%); herbal products (n=154; 92.8%) and traditional Malay therapy (n=147; 88.6%). About 83% (n=137) patients disclosed CAM use to their prescribers. Among these, 58 (42.3%) reported that their doctors encouraged the use, whereas 89 (65.0%) patients claimed their doctors disagreed the use of CAM. Conclusions Prescribers still have doubt in combining chemotherapy with CAM, hence patients use CAM discreetly. Increasing the awareness and understanding of CAM use are mandatory to distinguish its possible synergistic or adverse reactions with cancer patients.