Connect
Borderline SIBO/IMO? Two GIs disagree on rifaximin + neomycin
Hi all,
I’m trying to understand whether my lactulose breath test really looks like SIBO/IMO, or whether it looks more like a borderline/late rise. I have received two different gastroenterology opinions (one advising for rifaximin + neomycin, while the other one being completely against it) and I’m unsure how to proceed.
In short, I’ve been sick for about 6 months with nausea, poor appetite, weakness, bloating + gas. There have been days where I was so weak I could barely get out of bed. I ended up at urgent care and the ER a few times, but mostly received IV fluids and Zofran/Reglan for nausea.
Low-FODMAP plus gluten-free has helped a lot, but I’m still not feeling normal. I still get episodes if I try new foods, even small amounts of foods that should theoretically be safe.
My fructose breath test was called positive:
Fructose breath test
0 min: H2 2 ppm, CH4 7 ppm
60 min: H2 15 ppm, CH4 15 ppm
120 min: H2 27 ppm, CH4 19 ppm
180 min: H2 32 ppm, CH4 21 ppm
My lactulose breath test is what confuses me:
Lactulose breath test
0 min: H2 3 ppm, CH4 7 ppm
20 min: H2 2 ppm, CH4 6 ppm
40 min: H2 2 ppm, CH4 7 ppm
60 min: H2 2 ppm, CH4 5 ppm
80 min: H2 5 ppm, CH4 7 ppm
100 min: H2 18 ppm, CH4 11 ppm
120 min: H2 33 ppm, CH4 13 ppm
140 min: H2 42 ppm, CH4 15 ppm
160 min: H2 47 ppm, CH4 14 ppm
180 min: H2 55 ppm, CH4 15 ppm
So methane starts at 7 ppm and crosses 10 ppm only at 100 minutes. Hydrogen stays low until about 100 minutes, then rises later.
One gastroenterologist prescribed rifaximin plus neomycin for 14 days for SIBO/IMO.
Another gastroenterologist strongly disagrees. GI2 thinks this may be more of a post-antibiotic dysbiosis/permeability/malabsorption situation, because I had several antibiotic courses shortly before this started, and she thinks more antibiotics could make me worse.
For context, from Aug 2025 to Jan 2026 I had ceftriaxone/Rocephin IM plus 7 days of doxycycline for urethral/urinary symptoms, then 7 days of cephalexin/Keflex for the same thing, then 10 days of amoxicillin after one urgent care center labeled my throat symptoms as strep throat. I was also given topical mupirocin and clotrimazole. My gut symptoms started around Dec 2025, when I was also under a very large amount of stress.
GI2 wants me to first rule out celiac properly with EGD plus duodenal biopsies, then maybe MR enterography if needed.
Other relevant context: colonoscopy with terminal ileum and random biopsies was normal. Fecal calprotectin was elevated at 310.8. Stool analysis showed muscle fibers, starch granules and fat droplets, leading my endocrinologist to think it might be pancreatic. But my fecal elastase is >800. Celiac is not fully ruled out because I’ve been gluten-free, but HLA DQ2/DQ8 is positive. CRP/ESR were normal. MR abdomen/MRCP did not show obstruction, stones or bile duct dilation.
My stool pattern used to be one bowel movement every 1 to 3 days, lately improved to every day. Stool is usually light brown, stickier than normal, and forms soft blobs. I’m usually not clearly constipated and I don’t usually have diarrhea, unless I eat something my gut doesn’t tolerate. Then I feel nauseated for a few days, get diarrhea, and slowly improve again.
With all of this in mind, does this lactulose test look like true SIBO/IMO to you, or more like a late/colonic rise? Would you take rifaximin plus neomycin with this result, or would you work up celiac/small bowel inflammation first?
Like
Helpful
HugInterested in more discussions like this? Go to the Digestive Health Support Group.
Connect
Are you seeing both doctors simultaneously or is one a second opinion? If you put more than one doctor together you’ll often get differing results. Have you spoken to one of the 2 and asked for an explanation? You might also consider seeking the help of a nutritionist for diet. I successfully beat SIBO last year and am doing fine now. I still check my foods with FODMAP app though and I’m cautious with some food items.
-
Like -
Helpful -
Hug
4 ReactionsDid you end up taking rifaximin plus neomycin for 14 days, and the FODMAP diet? Do you have to stay with a pretty strict FODMAP diet?
I am suffering, again, with SIBO- off and on for years. I've just seen an allopathic doctor for years now- gastroenterologist. I did find a Functional Medicine doctor that I will be seeing in July. I sure appreciate a success story right about now.
Thanks!
-
Like -
Helpful -
Hug
3 Reactions@jenatsky Hi there - I've been diagnosed with SIBO. Interested to know what you did to beat the SIBO. Do you eat solely what's on the FODMAP app?
Hi, @wendyt2018 - really sorry to hear you are suffering with SIBO. What symptoms are bothering you the most right now?
@percy62 I was on an antibiotic for a few weeks to kill the bug. I’ve never felt GI docs were very good at given diet instructions so I opted for a nutritionist and I paid out of pocket. Yes I followed the FODMAP diet religiously using the FODMAP app to check what I was buying. It helped preventing me from throwing away food. My wife joined with me eating the same things I did since I do all the cooking anyway. With the nutritionist help I slowly brought back offending foods keeping a food and symptom journal. I also purchased products made by Gourmend that don’t have onion or garlic or at least the parts of the plants we cannot eat. I’m back eating normally now after about 9 months but I still don’t eat garlic or onion from the bulb in any form, only the plant tops that are made by Gourmend as a spice. They also have beef and chicken bone broth without onion or garlic. It’s certainly a journey and a relief to finally find out what the problem was.
-
Like -
Helpful -
Hug
2 ReactionsThank you and I appreciate you getting back to me. What were your symptoms when you ate something you shouldn't and how long did it take to show up after you ate it. I'm lactose intolerant as well. When you say your back to eating normally do you mean you're pretty much off the FODMAP other than the onion & garlic? Do you have follow up breath tests at all?
-
Like -
Helpful -
Hug
1 Reaction@jenatsky thanks for your very thorough reply. I strongly recommend anyone investigating Cibo purchase the FODMAP app from Monash University for $7.99. It helped me to avoid throwing out food, as well as allowing me to eat some of the forbidden foods e.g. I could have 2 asparagus spears, but no more. Since I have all or nothing black or white, thinking, this app helped me to moderate my food intake.
-
Like -
Helpful -
Hug
1 ReactionI too was diagnosed with IMO back in December 2025 but my issues extend to fecal body odor, suspected TMAU, severe osteoporosis, and currently at 80 lb weight. From what I read on IMO, I am inclined to believe what your GI2 said that taking antibiotics can make you worse. IMO is not bacteria but proliferation of archaea in our gut. Antibiotics are meant to kill bacteria. That is why methane SIBO was re-classified as IMO and not part of SIBO where the B stands for Bacteria. Wasn't there an explicit diagnosis by the dr who interpreted the breath test results? Mine stated that results were consistent with IMO. If it's IMO, maybe you could explore antimicrobials making sure there is no maltodextrin (Allimax Pro has maltodextrin in it) or fillers or preservatives. Yes, no doubt stress wreaks havoc to our guts! Took neomycin for 10 days which resulted in ER on Christmas Day because of severe dizziness as dr ignored my low weight and mild hearing loss (which was a red flag on the prescription insert ). You should also ask pharmacist for clarification or explanation of any medication that you plan to take because sometimes they will give you a different perspective from what the dr tells you. I can't offer any solutions for you because I am still challenged at this time. What I will do for you is to pray for your healing! I believe in miracles!
-
Like -
Helpful -
Hug
1 Reaction