I've been treating SIBO for ~6 weeks after a positive lactulose breath test. My results showed the classic 'twin peak': 0ppm baseline, first peak @42ppm hydrogen and second peak 64ppm hydrogen. Methane started at 3ppm and fluctuated between 0 and 6ppm. I had been low FODMAP for years and very low carb (keto) for 4x months prior, so although still clearly SIBO positive I suspect my results were attenuated by diet somewhat. Certainly ignoring the very restrictive diet led to completely intolerable symptoms.
First 10x days was Rifaxamin & Garlic Plus. I was told this was to target hydrogen producing bacteria, with the garlic there to control any methane producing bacteria overgrowth. Garlic was in place of metronidazole, as my methane levels were borderline so deemed perhaps not worth the risk of systemic antiobiotic treatment.
Zero side effects, my bowel movements improved immediately and towards the end of the course I was feeling really quite energetic indeed. I had been on a gradual upward trajectory since starting the keto diet but this did seem to give me a good shove in the right direction. For the first time in months I went the full 10 days without any Pompholyx eczema breakouts or stomach reactions from eating, I had more in the tank and didn't suffer usual migraines after pushing it.
Following the 10x day course I started Candibactin AR (Oregano Oil), Candibactin BR, N-acetylcysteine (biofilm disrupter) & Garlic Plus. I brought them in gradually: low dose and 1x at a time. I immediately had sustained gut and skin reactions and felt fatigued with more migraines. I took ~1 week to reach full dose (4x AR, 6x BR, 3x NAC, 3x Garlic p-day), by this time feeling of ill health had increased and I was experiencing full-on stomach pain & nausea, worsened POTS/OI symptoms and fatigue significant enough to cause me to sleep during the daytime. Thankfully these significant problems lasted 4-5 days and abated, leaving me with just the slightly reduced energy and tolerable skin/gut reactions again.
My naturopath didn't use the term herx or die-off, but considered it the result of the herbs working. She advised that herbs work along the entire gut, unlike Rifaxamin which primarily targets small intestine, and that it was probably the result of the herbs inhibiting con-current yeast/pathogens in the large intestine too. I was very close to pulling the plug on them as I felt incredibly rotten! But will now continue for the full 2 month course.