In the UK they dont bother testing you for SIBO any more.They stopped doing the breath test.I responded to antibiotics but a question is that does IBS cause SIBO or SIBO cause IBS. My symptoms came back quickly when I stopped the antibiotics.I took 1200mg of Xifaxan for 10 days several months ago. I was not tested for SIBO first, and it did not seem to help my symptoms. In addition, I did not tolerate this drug well at all. I got horrible cramping and burning pain which peaked on day 8, much much worse than my "usual" IBS pains and cramping. Also, while my stools are generally pretty regular (mild IBS-A), this made me horribly constipated, and it took a full two months to resume normal function without the help of Miralax.I would not take this drug without a positive test for SIBO.