Although all Chinese materia medica (CMM) come from nature, CMM interventions have therapeutic effects and adverse effects (AEs). Normally, AEs in randomized controlled trial (RCT) with traditional Chinese medicine (TCM) could be divided into five types as follows: 1) AEs under proper TCM principles and guidelines, such as the toxicity (acute and chronic) and allergy; 2) AEs due to improper usage without following TCM principles, involving without following the TCM therapeutic principles, over-dosage, improper processing and preparation methods, improper formula strategy, etc; 3) AEs due to contamination in CMM, such as heavy metal and pesticides contaminations in Chinese herbal medicine interventions, and intentional or unintentional contamination with drug(s); 4) AEs due to replacement of CMMs; 5) AEs due to drug-herb interaction. AEs of TCM should be treated properly. Overestimation or underestimation about AEs of TCM intervention will bring a wrong message to patients and health care providers. In order to give readers a more comprehensive understanding about the safety issue of study intervention, Consolidated Standards of Reporting Trials (CONSORT) for TCM should involve the background information on side effects of each CMM constituents and/or the study intervention, specific outcome assessment on AEs, the details of reported AEs and the interpretation of the AEs occurrence in a structural RCT report.

Key words: traditional Chinese medicine, Chinese herbal drugs, clinical research, randomized controlled trials, evidence-based medicine