Limitations
The main limitation in this study was related to determining scientific names of herbal medicines because some of the herbal medicines with one common name have several scientific names which are different in therapeutic properties. For this issue, the herbalists selected the prevalent species of herbal medicines in our country (Iran). The other limitation was underestimation of herbal medicines which patients used. Because they used some herbal medicines but did not remember the name of them due to recall bias. The other limitation of this study is related to the design of the study. As this was a cross-sectional study, we could not confirm the causation of the predictor variables with the potential herb-drug interaction as the outcome.