Hello Lin, Thank you for asking at HCM. I went through your son s history and would like to make suggestions for him as follows: 1. Ibuprofen is a common cause of allergic reactions, however, it is not always a drug that may be causing allergic reactions. It is possible that some additives in the drug formulations which may be causing reactions. 2. To decide whether he is truly allergic to ibuprofen, your allergist will take history of each reaction in great detail, including which other drugs were given, whether ibuprofen brand were same or different, etc etc. This will help him to decide whether it is a true allergy or false allergy. 3. However, such self-limiting reactions (whether allergic or non-allergic) usually do not cause permanent damage, especially if he is completely normal between reactions. So at present, I would suggest you not to worry about such permanent damage. Unfortunately, there are no tests available identifying or ruling out such damage. 4. If he is allergic to ibuprofen, I would suggest him to avoid it in future. There are many other options available for fever/pain symptoms other than ibuprofen. 5. For diagnosis of ibuprofen allergy ( true allergy), your allergist might suggest him blood testing and skin testing, which should be interpreted by an experienced allergist-immunologist to decide whether he is truly allergic to ibuprofen. Hope above suggestions or information will be helpful to you. Should you have any further query, please feel free to ask at HCM. Wish your son the best of the health ahead. Thank you & Regards.