This paper is well structured and easy to understand. The introduction was logical and explained background information clearly. Moreover, a vast amount of data was collected in a wide range of time period. However, I believe the study could be more interesting and reliable if the authors collected the data by themselves, not from secondary organisations.

Title, abstract, and references: The title of the study summarises the study purpose. The abstract clearly shows the aim of the study and the conclusion from the study. The references used in this study are relevant and ranged from 1968 to 2015.

Introduction/background: The introduction is concise and rational. It explains why its topic is important and why this study has to be done. The introduction explains reasons for the use of antibiotic prophylaxis and reports the updated guidelines that encourages to reduce the antibiotics prescription, which differs to the previous guidelines.

Methods: Overall, the methods are well explained and specified the time frame for each drug and its use. Furthermore, the data was collected from two UK government health organisations, however, the data was limited to cases which voluntarily reported by health professionals in UK and not all cases were reported.

Data and results: Results were presented clearly for each antibiotics, which are amoxicillin and clindamycin. It included the number of prescriptions for each drugs and adverse reaction cases of each drugs. It was logical and easy to understand through several graphs.

Discussion and conclusions: Discussion was well-structured by dividing into each drugs and antibiotics in general. By sectioning into three, it was easy to read and helped reader's understanding. Authors discussed the limitations of the study as well as suggestions for the future studies, which enhances the paper's credibility. Overall, discussion is well structured and written.