Dr Pimentel SIBO IBS Drugs

SIBO Expert Dr. Pimentel on Drugs for SIBO and IBS

In my last post, I recapped Cedars-Sinai SIBO expert Dr. Mark Pimentel’s Twitter chat on food and diet related questions on IBS and SIBO. Now, I’ll recap his answers to questions about drugs for SIBO and IBS and explain to  you what’s new and surprising in the world of SIBO and IBS drugs.

Drugs for IBS generally attempt to just treat the symptoms without solving the root cause. Doctors or patients often use Imodium or Pepto Bismol, or prescription drugs like tricyclic antidepressants, to treat IBS-D by slowing down the digestive system. For IBS-C, patients and doctors use drugs that cause more water to enter the digestive tract, like magnesium, or use laxatives, which irritate the digestive system.

For SIBO, treatment with drugs usually consists of antibiotics (pharmaceutic or herbal) followed by a prokinetic to stimulate the migrating motor complex’s cleansing waves. This protocol is what I followed when treating my SIBO.

Let’s see what Dr. Pimentel had to say about drugs for SIBO and IBS in the Cedars IBS Chat on Twitter last month.

You need antibiotics to fully treat SIBO.

Often times I see people say that a low FODMAP diet is all you need to treat SIBO. While a low FODMAP diet helps alleviate many SIBO symptoms, it won’t treat the underlying problem. This tweet addresses a similar issue: can you just take laxatives and treat the symptoms of SIBO? Will this be enough to cure it?

The answer, as I suspected, is no. It’s interesting to me that laxatives actually do help reduce methane. Presumably this is because getting things moving through your gut instead of letting fermenting in your digestive tract reduces the food for the bacteria. Less food for bacteria = less bacteria.

Dr. Pimentel then states what I suspected: that you really do need to get rid of all the bacteria with antibiotics instead of just reducing them through laxatives. I suspect this same reason is why it doesn’t’ work to do a low FODMAP diet without using antibiotics first. The diet helps by giving the bacteria less food, but ultimately, we need a stronger method to get rid of the bacteria first. That’s what the antibiotics are for.

Speaking of Antibiotics and the Low FODMAP diet, do not combine the two!

This tweet has since been removed but from the response it seems that it asked why a course of antibiotics might not work. It seems pretty common in SIBO treatment that a course of antibiotics fails. Many people have to take multiple antibiotic courses to eradicate their SIBO. For others, it doesn’t seem to work at all.

Often on the SIBO groups I’m a part of, I see people asking whether they should start a low FODMAP diet while on antibiotics. The answer, as always, is NO!

As Dr. Pimentel notes, the bacteria go into survival mode when they do not have enough food. This makes them harder to kill. Instead, you need to feed them with lots of nice yummy FODMAP containing foods. When the bacteria are well fed and replicating is when the antibiotic is most effective.

So remember…if you’re on an antibiotic (at least a pharmaceutical one) then wait until after you’re done to start your low FODMAP diet.

It’s unclear what drugs treat Hydrogen Sulfide, a new SIBO gas.

Hydrogen sulfide in SIBO is not something I knew about until very recently. A standard breath test for SIBO tests for methane or hydrogen. However, sometimes people will have negative breath tests and still have symptoms.

A 2016 study showed that the culprit in those cases might be a gas called hydrogen sulfide. Like methane and hydrogen, bacteria that overpopulate the intestine in SIBO can give off hydrogen sulfide. But there is no widely available, standard breath test yet for hydrogen sulfide.

Unfortunately, it seems like even the expert, Dr. Pimentel, doesn’t have a good answer yet for how to treat hydrogen sulfide. That’s disappointing, but hopefully something that researchers are studying. It would be useful to have more antibiotics or other drugs for SIBO and IBS that attack a wider range of bacteria and symptoms. Perhaps studying hydrogen sulfide will lead to that.

In the meantime, the takeaway is that if you have a negative breath test but still have symptoms, you may have SIBO with hydrogen sulfide producing bacteria. One potential treatment idea would be to try an Elemental Diet. That way, you don’t have to wonder if you have the “right” antibiotic to kill the bacteria because you are starving all of them, presumably.

Rifaximin doesn’t cause bacterial resistance.

You know how I mentioned earlier that it’s very common to need multiple courses of antibiotics? Back to that theme.

Antibiotic resistance happens when bacteria adapt and change after encountering an antibiotic. They change so the next time you take the antibiotic, the bacteria can resist it and continue thriving. Sadly for us this means the antibiotics stop working.

Many times I’ve heard from SIBO patients who say their doctor treated them with Flagyl, Cipro, or some other antibiotic that is not Rifaximin. I’m skeptical of the success of those because Rifaximin is specifically absorbed in the small intestine, unlike other antibiotics. That Rifaximin doesn’t cause antibiotic resistance confirms another good reason to use it as a first line treatment for SIBO.

Bottom line: if your doctor prescribes you an antibiotic other than Rifaximin as the first attempt at SIBO treatment, ask him/her why. Insurances often require prior authorization for Rifaximin, so be prepared to tell your doctor why Rifaximin is superior if he/she does not already know. Not all drugs for SIBO and IBS are created equal!

What the heck is the diarrhea drug Ondansetron?

I will say it’s pretty rare when there are drugs for SIBO and IBS that I haven’t heard of. This is one such case though!

IBS and SIBO often manifest in diarrhea (mine included!). I thought I heard of pretty much all the drugs used to cope with diarrhea. That includes tricyclic antidepressants, antispasmodics, imodium (which is an opiate). But I hadn’t heard of this drug that Dr. Pimentel mentions, called Ondansetron. The brand name is Zofran.

Doctors generally prescribe Ondansetron to alleviate vomiting and nausea caused by chemotherapy. Chemotherapy drugs cause the body to release serotonin cells in the small intestine, which stimulate the vomiting reflex. By blocking this serotonin, Ondansetron prevents vomiting. Instead of swallowing the drug, it’s dissolved on the tongue.

Studies have shown that Ondansetron can improve diarrhea for IBS patients. Personally, I wish my doctors had known about this drug back when I went literally years with just an IBS diagnosis. I found that tricyclic antidepressants didn’t change my symptoms, and imodium caused bloating and discomfort.

Have you tried Ondansetron for IBS? What was your experience? Let me know in the comments!

Magnesium: A-ok to take, but beware…

Magnesium can be a great supplement. It keeps the heart, bones, and teeth strong. It can help relieve stress and relax muscles. Unfortunately, it also draws water into the intestines which can cause diarrhea.

I once saw a naturopath who diagnosed me with a magnesium deficiency by testing my muscle reflexes. He prescribed me a magnesium supplement…which I definitely did not take because I wasn’t about to chance more diarrhea! But sometimes, we really do need more magnesium than we are getting through our diets.

I think the original questioner here wondered whether taking a prokinetic, which stimulates the migrating motor complex, would work at cross-purposes with taking magnesium. But prokinetics and magnesium work differently. Magnesium draws water into the intestines, which causes looser stools. A prokinetic causes more cleansing waves of the small intestine.

So magnesium and prokinetics don’t work the same way. As Dr. Pimentel says, one should not affect the other. Just make sure that when you take magnesium, you start with a low dose and work your way up to make sure you won’t wind up in the bathroom too much! That goes for whether you take it with a prokinetic or by itself.

That’s all for now on drugs for SIBO and IBS…

Well, I think that covered all the questions Dr. Pimentel answered about drugs for SIBO and IBS. Were there any questions I missed, or anything you’re wondering about? Don’t forget to check out my post about what Dr. Pimentel had to say on food and diet, and leave me a note in the comments below!

30 comments

  1. Rifaximin is neither affordable nor permited for treating IBS and/or SIBO in Australia. I’de like to use Erythromycin at a dose of 250mg bid, 7-10 days. Clearance and prokinetic in one. I would appreciate Dr Pimentels’ response indicating clinical advantage/disadvantage if possible please.

  2. Hi Margaret, low dose erythromycin is used solely as a prokinetic, at very low doses (I cut a pill into quarters that each end up being around 62mg I believe). At that low dose, I’ve been told, it doesn’t act as an antibiotic because it’s so small–only acts as a prokinetic at that dose. I have never heard of Erythromycin being used short term in larger doses as an antibiotic for clearing the bacteria in SIBO, so I don’t believe it’s used for that, probably because it isn’t effective at that. If you can’t get Rifaximin, I might suggest looking into herbal antibiotics, some of which have also been studied for SIBO and found as effective as Rifaximin. You can read more about those here: https://sibosense.blog/2018/06/17/all-about-treating-sibo-with-herbal-antibiotics/

    Best of luck!

  3. To me, my worst symptom is terrible breath from SIBO. I don’t see many people speak about that problem. I’ve been on two courses of antibiotic so far. Is this a common symptom.

    1. Hmm, I haven’t really heard that as a common symptom. Maybe ask your doctor? Sorry, I don’t have any advice about this one!

    2. Yes I agree!!!! bad breath is a symptom that I struggle with as well. I have reoccurring SIBO and when my numbers were in the normal range I notice a significant change in my breath issues. I use an organic peppermint oil breath spray and I am very self contentious about standing close to people to talk. Having a major impact on my social life and I agree should be acknowledged as we need a support system while working through the affects of SIBO on our lives.

      1. I would recommend using the mouthwash brand Therabreath. Best mouthwash for bad breath and halistosis. Helped me with my breath within a few uses!

  4. All Dr.pimentel is talking about here is DIAREA!!! I wish I had diarea !!!!–I have IBS CONSTIPATION !!!–he says only that it is harder to treat ..so why nobody is adressing us IBS-C sufferers ? wwe are in pain and need too and even more so !!!!btw–Neomicyn (mentioned many times together with Rifaximin for IBS-C ) is OTOTOXIC !!!=toxic for the inner ear !!! it can cause hearring loss–I am a proffetional musician–so for me it is absolutly no option

    1. The common advice is to start afterwards. You want to just eat normally while on antibiotics as apparently when the bacteria are feeding and replicating is when the antibiotic is most effective. Seems counterintuitive but this is how it is!

  5. Hi Emily, Thank you very Much for your Blog it is of great help. I have being diagnosed with IBS- Constipation. After I was prescribed PPI for 5 years due to Acid Reflux My Doctor decided to take me out of this medication. After two years having Digestive issues and motility issues I was diagnosed wit IBS-C. I was prescribed Rifaximin for 10 days but now thanks to your Blog and discovering Dr Pimentel and not feeling totally well ( clearly the bacteria is still producing a lot of Methane Gas ) I am wondering if I should go in a second round Of Rifaximina and Neomycin Antibiotics? Do you Know if Neomycin has more side effects or dangers for the Bowls walls? I was diagnosed with IBS at Mount Sinai in NYC through a Colonoscopy and a Gastroscopia not the breathtest. Do you think the Breath Test is fundamental? My diagnosed was for Constipation as they could see not a lot of bowel movements and Constiapation on the digestive track They said they did not need the breath test. Thank you for your Help. Best Wishes, Maria.

    1. Hi Maria, I would ask them why they think you do not need a breath test and how they have ruled out SIBO without a breath test. To my knowledge (I am not a doctor), constipation is not a diagnosis in and of itself really – it describes a symptoms. But the cause of the constipation is what you’ll want to address. However, it sounds like if you’ve been prescribed Rifaximin they are at least trying to treat it. I would ask about Neomycin as well, as that is the antibiotic which has been shown to be effective for constipation when combined with Rifaximin. Good luck!

  6. Since you asked, I took ondansetron for several months for extreme nausea, lost 55 pounds, and still don’t have a diagnosis. I have chronic diarrhea (40 years). The digestive doc I went to knew nothing of any of the diagnoses or tests that Dr. Pimentel talks about. Never mentioned SIBO or IBS. The ondansetron only worked somewhat (on it I wasn’t suicidal). Otherwise, the nausea made me want to die. And the diarrhea got so bad I didn’t leave the house for 4 months, black water sometimes lasting all night. My stool is still black but solid. I am also diabetic so I’m very careful about what I eat. . I take many supplements, a low carb diet, no starches, sugars, dairy, grains, only berries for fruit. I am presently taking daily ozone treatments (rectal) which have apparently eased the diarrhea (only 1 day in the last 14) which is monumental to me. I’m still hoping for a definitive diagnosis and someone to treat.

    1. Interesting, I haven’t heard of ondansetron before. I would see if you can find another doctor who is more current on their research. It’s pretty well established that SIBO is a biological disease process at this point, in my opinion there’s no excuse for gastroenterologists not being at least aware of it. It must be challenging to manage both the diabetes and your digestive problems. I am sorry and hope that you find a doctor who is more willing to educate him/herself and help you!

  7. Hi, Bob here. I’d be interested if any chronic SIBO patients tried high-dose Vitamin C, as mentioned by Dr. Tom Levy, M.D. and if so, what were their results? I’d be esp. interested if anyone did the Vitamin C flush (orally taking enough until you have basically clear water coming out the back end) during a full moon, when parasites are known to be active? Likewise interested if enemas or colonics helped anyone?
    https://www.peakenergy.com/articles/nh20140311/Reversing-disease-with-the-'multi-C'-protocol/

    1. Hi Bob, I’ve never heard of high-dose vitamin C as a treatment for SIBO, and it’s unclear to me by what mechanism that would either kill bacteria, and/or stimulate the migrating motor complex. I don’t see any mention of either of those in the link you sent. I would be very skeptical of any regime proposed by this Dr. Levy, who, from a quick peruse of his website, does not accept the overwhelming and conclusive medical/scientific data confirming that vaccines do not cause autism, and that vitamin c can completely cure most bacterial and viral infections, which is patently untrue. He also cites no sources for most of his assertions. So, be skeptical is my advice. As for vitamin C dosage, my research suggests that 2,000mg is the upper limit dosage. Also, there is no scientific evidence I can find suggesting that parasites are affected by the moon phases. Hope this helps.

    1. I answered my own question on one of your other posts: low dose erythromycin, LDN, Iberogast and prucalopride. If you can think of any others (besides Zelnorm), I’d love to know them. I’ve failed with all of these and I’m in a bad way. Thanks!

  8. How does one treat SIBO with antimicrobials in a case with demonstrated risk of C. Diff infection? 8 months had passed since initial treatment of C diff prior to treatment of SIBO with Rifaximin 10 day course. Resulted in recurrent C Diff infection despite Rifaximin ‘only being active in small intestine’ which is clearly not the case.

  9. Hi, I am waiting for a SIBO breath test from my GI. I have had very weird inflammation issues for a long time. I had bad acne before that. Primarily problems on my face for a very long time and my nutritionist thought I had Candida and food sensitivities 3 years ago. I did a very strict diet and it seemed to be better. At the time, I did have gas and upset stomach at times but those symptoms improved after pretty much eliminating dairy, gluten and sugar (when possible). Well the last 7 months have been stressful and my facial inflammation was not great in the last few months but has gotten very bad (in the last 5 weeks) and cannot seem to get to the root of the problem. Like feeling like I have an infection under the skin with lots of pain. Have taken too much ibuprofen which showed redness on endoscopy. I was negative for H pylori. I had an endoscopy on Nov 2nd and my GI suggested doing the SIBO breath test last week. I am waiting for test. I don’t think its Candida this time but some type of bacteria. Can you have SIBO without any stomach issues? My main issue is facial inflammation but its not acne. Something is triggering it. I have ruled out so many other things. So, I have have been on a very strict diet since Thursday (for the last 6 days) and my symptoms are better. I have been taking Goldenseal. This is so very challenging as I am trying to get started on a course of action as my skin was so bad. My strict diet seems to be helping but I am not sure if I am doing the right thing. Please comment on other symptoms besides stomach issues and let me know if anyone else has inflammation issues with SIBO. Thank you so much!

    1. I am an 82 year old man who discovered that I had a bad allergy (acne) to milk products at age 22. Completely eliminating milk products caused my acne to improve at least 80%. The key to your statement is: “pretty completely eliminating milk.” I did seem to tolerate yogurt. The last 2-3 years I cheated eating some ice cream and drinking eggnog in the holiday season. I stopped all that this January 2022. In July 2022, My Quintron H2 went up 30 points for H2 after lactose, when the diagnosis suggests a minimum of 15. It is hard to figure out what the culprits are sometimes. Even white fudge has milk in it (darn it). I am on xifaxin starting today. You say it is not acne, but you do not know if milk is your problem, unless you do a really careful study. Good luck!

    2. There is also a carbohydrate malabsorption breath test that can check for both lactose and fructose intolerances. But getting the SIBO test first is a good idea, because if it comes back positive you will want to clear that up first before doing the carbohydrate breath test.

  10. My question is if you have seen/heard of anyone having diarrhea after getting the CoVid vaccine? I got the J&J 2 weeks ago and have had intermittent diarrhea ever since. I am doing Low FODMAP and was diagnosed with H SIBO years ago. I am reluctant to take an anti diarrheal – this is getting old and I have a call into my Dr. wondering if I need a new dose of abx? I read that the actual virus can hit the intestinal tract pretty severely but cannot find any information about the vaccines.
    Thank you,
    Desperate in CO

    1. I have not heard this, I would definitely call your doctor about it. SIBO can wax and wane and so maybe you need another course of treatment? Just a guess. Good luck!

    2. Donna your question made me think of my issue – I have had IBS for 30 years but just after my first vaccination my stomach got really bloated (never really had that problem before). No one made any connection, even though I mention it. Still have no idea… STILL am too bloated after 2 years…

  11. Six months ago I got explosive diarrhea the day i was diagnosed positive for Covid. It calmed some but I still had many loose bowel movents every day for more than a month. At this point I have a loose BM after each meal. I also have bloating, nausea, gas, some stomach pain and a feeling of being too full but at the same time very hungry. During the daytime the symptoms are lite enough that I can deal with them but at night they are worse to incapacitating. A complication is that I have had GERD for years and started a year ago taking daily Pantoprazole. So I am wondering if Covid plus Pantoprazole are causing me to have something like SIBO. This is the first I have heard about SIBO so I would very much appreciate your comments.

  12. Curious if taking immodium keeps the bacteria in when you have diarrhea. I try to let it play out but eventually it gets to be too much and I have to take it. Does this make the SIBO worse?

  13. Interesting that the last comment was a year ago. I would like a reply for the latest comment about Immodium.

  14. Emily – I know this is an old thread but I wanted to clarify your non-use of Mg. Only certain forms of Mg cause constipation, like Mg citrate. When taking a laxative such as Milk of Magnesia, you are getting a very large dose of Mg citrate. Since this is poorly absorbed, the Mg is dumped to the intestines to intentionally cause loose stool.

    However if you take another form of Mg, one that is better absorbed, you will take a low dose and you will get the benefit of the Mg you need without a laxative effect. Consider Mg glycinate or bis-glycinate. Pure Encapsulations is a good Mg brand to try.

    Making too many assumptions based on too little knowledge can be harmful to your health. Please give yourself what you need to heal. If you look hard enough you will find good solutions.

Leave a Reply