The prevalence and predictors of herb-drug interactions among Iranian cancer patients during chemotherapy courses

BACKGROUND: The concurrent usage of herbal medicines with conventional therapies is an important concern in cancer treatment which can lead to unexpected consequences like herb-drug interactions. This study aimed to determine the prevalence of potential herb-drug interactions and to predict factors associated with herb-drug interactions for cancer patients. METHODS: This cross-sectional study was conducted among a convenience sample of 315 cancer patients referring to the oncology clinics of Kerman city in 2018. Data were collected via comprehensive face-to-face interviews and medical chart reviews. A drug interaction checker was used to determine herb-drug interactions. The information of patients was compared based on herb-drug interactions using bivariable logistic regression models, and predictors were determined by the multivariable logistic regression model. All analyses were performed by Stata software version 16. RESULTS: Of 262 patients (83.2% of the patients) who used herbal medicines, 209 patients [79.8% (95% Confidence Intervals (CI): 75.2 – 85.1)] had potential herb-drug interactions. Chamomile was the most popular herbal medicine (n = 163, 78.0%), and minor and moderate herb-drug interactions were caused by green tea (n = 34, 16.3%) and peppermint (n = 78, 37.5%). The number of chemotherapeutic agents (OR: 1.92, 95% CI: 1.43–2.58; P-value < 0.0001) and the experienced of pain during chemotherapy courses (OR = 2.22, 95%CI:1.00–4.94; P-value = 0.04) were some of the predictors of herb-drug interactions among cancer patients. CONCLUSION: Herbal medicine use during chemotherapy was found prevalent among cancer patients; of them, the experience of potential herb-drug interactions was highly frequent. Oncologists and clinical pharmacologists are recommended to take into account challenges associated with herb-drug interactions in their routine practices, particularly during chemotherapy among these patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12906-023-03869-1.