Hi, There s no documented evidence of any harmful interactions between the antibiotic Xifaxan and Adderall. However, taking Adderall along with Zoloft or trazodone can increase the risk of a serious condition called the serotonin syndrome, which is characterized by confusion, hallucination, seizure, increased heart rate and blood pressure, fever, excessive sweating, muscle stiffness, tremor, incoordination, stomach cramp, nausea, vomiting, and diarrhea. In its severe form it may result in coma and even death. Hence it is not safe to take these medications together or ask his doctor for either dose reduction or to prescribe alternate effective medications. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Mohammed Taher Ali, General & Family Physician