A course of SIBO antibiotics is often one of the first recommendations from any gastroenterologist to treat SIBO.

This is because antibiotics are one of the quickest and most effective treatment options available for people suffering from SIBO or IBS.

But, there are things you NEED to know before proceeding with one of these treatment options.

In this article, we will break down everything you need to know about SIBO antibiotics including:

  • How they work to treat SIBO and IBS
  • Which antibiotics are used and what it means if they don’t work
  • What Xifaxan is
  • What you need to know about the treatment protocols before you proceed, so you can have the best outcome

How Do Antibiotics Treat SIBO and IBS?

First of all, if you don’t understand the basics of small intestine bacterial overgrowth which is found in 60-80% of people with IBS, I would recommend reading this article.

Basically, antibiotics treat SIBO by killing the overgrowth of bacteria in the small intestine.

Antibiotics do this by either stopping bacteria from replicating or destroying them. The reason we want to kill bacteria is that people with SIBO have accumulated too many bacteria in their small intestine (there should be much less) which cause debilitating digestive symptoms such as gas, bloating, diarrhea, constipation, fatigue, and abnormal stools.

When you treat this imbalance of bacteria in the small intestine with specific antibiotics, you reduce the amount of gas being produced, which can reduce symptoms.

For some people just treating this bacterial overgrowth can solve the problem, but others will need to address other underlying causes which enabled this bacterial overgrowth in the first place. (We will touch upon prevention later)

Xifaxan for SIBO and IBSXifixan for IBS

While there are a few different antibiotics usually prescribed to treat SIBO and IBS, the most common antibiotic is Xifaxan (Rifaximin).

Xifaxan is a non-systemically absorbed rifamycin with antimicrobial activity against gram-positive and gram-negative aerobic and anaerobic organisms.1

Xifaxan is used to treat traveler’s diarrhea, hepatic encephalopathy, IBS/SIBO, and a few other bowel infections.2

The main difference between Xifaxan and other SIBO antibiotics is that it is very minimally absorbed throughout the body and works specifically in the gastrointestinal tract.

This means that you are less likely to have toxic or systemic side effects compared to other antibiotics.

Also, the solubility of the drug increases 100-fold in the presence of bile acids (which are delivered directly to the small intestine after eating), meaning that its antimicrobial effect is much greater in the small bowel than in the colon.3

More so, Xifaxan decreases mucosal inflammation which is likely another reason it helps IBS patients. 4 Because of these properties, Xifaxan is a top antibiotic chosen for SIBO treatment.

Xifaxan for IBS-D

Xifaxan has been studied and used in all subsets of IBS and SIBO patients including diarrhea, constipation, and mixed type patients. But, it’s important to understand that there are differences in the study results when Xifaxan is given under different protocols for diarrhea and constipation type patients. In this section, we will go over Xifaxan’s use in IBS and SIBO patients with diarrhea specifically.

Xifaxan is one of the best antibiotics for SIBO and IBS with diarrhea.

In a number of different studies, it has been shown that a 2-week course of Xifaxan at a dose of 550 mg 3 times per day provides significant relief of IBS/SIBO symptoms, such as bloating, abdominal pain, and loose or watery stools.

The only thing you need to keep in mind when using antibiotics is that relapse can occur after treatment, so it’s vital to take preventative measures and continue to improve your overall digestive function.

That being said, using Xifaxan for SIBO in patients who have diarrhea as a predominant symptom is usually a very effective option.

Xifaxan Dosages for Diarrhea

  • 1200 mg per day for 10 days with 5 g per day of partially hydrolyzed guar gum (source)
  • 1650 mg per day for 14 days (source)

Xifaxan for IBS and SIBO with Constipation

Xifaxan is also used in constipation cases but there has been different research findings and outcomes using it with constipation.

It’s important to note that usually Xifaxan is used alone only in people with diarrhea or mixed type symptoms, whereas it is used in combination with other medications in constipation-predominant cases.

Despite this, there is some evidence that Xifaxan alone can help some people with constipation, such as this study.

As with all medical treatments, each person has a unique body and using Xifaxan alone for constipation may not be helpful for everyone. But, it has been reported that using Xifaxan in combination with Neomycin (rather then either alone) for constipation can be much more effective.

In this study, patients who tested positive for methane on the SIBO breath test (which usually indicates constipation type symptoms) were split into 3 groups. One group got Xifaxan alone, one just Neomycin, and the last group a combination of Xifaxan and Neomycin.

This table shows the results:

PROTOCOL  DOSAGE METHANE ERADICATION
Rifaximin + Neomycin

1200 mg Rifaximin1000 mg Neomycin

10 days

87%
Neomycin Alone 1000 mg Neomycin10 days 33%
Rifaximin Alone 1200 mg Rifaximin10 days 28%

85% of patients getting combination treatment also noticed an improvement in their symptoms. These results show why Xifaxan alone is not the best option for those with constipation type symptoms;  Xifaxan and neomycin work synergistically to treat different organisms in the gut, improving overall symptoms.

Xifaxan Combo Dosages for Constipation

  • 1200 mg Rifaximin + 1000 mg Neomycin per day for 10 days (source)
  • 1650 mg Rifaximin for 14 days + 1000 mg Neomycin for 10 days

The Pros and Cons of Using Xifaxan for SIBO

sibo antibiotics pros and cons

There are pros and cons when deciding to use SIBO antibiotics like Xifaxan.

Here is a list of both sides, so you can make the best decision possible

Pros:

  • Works quickly when effective
  • Protocols have been researched thoroughly
  • One of the strongest treatment options
  • Xifaxan is a non-absorbable antibiotic so it doesn’t cause as many systemic side effects
  • Xifaxan can reduce mucosal inflammation

Cons:

  • Xifaxan is very expensive, without insurance it usually costs around $1,500
  • Xifaxan can still cause negative side effects (though it doesn’t happen as often since it acts mostly in the gut)
  • You can still relapse after a successful treatment if there is a stubborn underlying cause 
  • Xifaxan isn’t as effective in constipation cases and needs to be combined with Neomycin

Relapse Rates After SIBO Antibiotic Therapy

sibo antibiotic relapse rates

I think it’s important to touch on the relapse rates after using antibiotics for SIBO. This helps you make the decision whether to try natural treatments initially or go straight to antibiotics, especially if you have to do multiple courses.

I think you will find that in the long run, it’s important to incorporate a mostly natural strategy, only using pharmaceuticals when your symptoms are very severe.

In this study, the aim was to investigate SIBO recurrence in patients after successful antibiotic treatment. They took 80 patients treated with Xifaxan and reassessed them 3, 6, and 9 months after their breath tests normalized. The results are informative and very important for people who use antibiotics to understand.

The Results:

  • 3 months after successful antibiotic treatment 10 patients (10/80 or 12.6%) tested positive for SIBO again indicating relapse
  • 6 months after successful antibiotic treatment 22 patients (22/80 or 27.5%) tested positive for SIBO
  • 9 months after successful antibiotic treatment 35 patients (35/80 or 43.7%) tested positive for SIBO

They also showed that being older, having your appendix out, and chronically using proton pump inhibitors (like Prilosec) increased the chance of relapse. This means that if you have other health issues that are affecting your gut function you will be more likely to relapse and become a chronic SIBO patient.

This study is very important to understand; it shows that while antibiotics can definitely help a lot, they are only one helpful tool in the overall treatment strategy, and not a magic cure. In reality, many people deal with relapse and have to find a combination of strategies to help maintain their symptom relief while preventing recurrence.

Why Does SIBO Relapse?

This is a great question to ask any doctor or researcher who studies SIBO or IBS. There are many hypotheses right now but no final conclusion. Whoever figures out the solution to the relapse problem will be a rock-star! As mentioned above, SIBO is often a chronic condition, and like the study above showed, recurrence can occur even after a successful course of antibiotics.

It is thought the main reason recurrence occurs is that there is an underlying problem with gut function or the migrating motor complex (MMC).

Some patients who develop bacterial overgrowth have abnormal MMC, meaning that the waves that normally cleanse their small intestine are not effective. Therefore, they do not clear the bacteria and undigested materials as well as other people.

When these small intestine cleansing waves are damaged, it allows bacteria to accumulate, causing SIBO symptoms.

Some of the main prevention strategies which help SIBO patients are:

  • Eating a healthy lower carbohydrate diet
  • Prokinetic agents (natural or pharmaceutical)
  • Fixing other issues that decrease gut motility
  • Reducing stress and making healthy life changes (high stress can decrease motility)

What Does it Mean if SIBO Antibiotics Don’t Work?

While antibiotics are usually very effective for SIBO (at least in the short term), for others, they may not work at all or for only a very short period of time.

This can be very frustrating. So, what does this mean?

This can mean a few things:

  • The SIBO antibiotic protocol was not appropriate for your specific gut bacteria
  • You need an additional course of antibiotics or an elemental diet to treat your stubborn microbes
  • You have developed antibiotic resistance, meaning the bacteria are not affected by the antibiotics
  • You don’t really have SIBO, but instead a different type of gut dysbiosis or health issue
  • If you relapse very quickly, you may need to focus on figuring out any underlying causes that may be contributing

Can You Treat SIBO Without Antibiotics?

yes, you can treat sibo without antibiotics

This is an important question many people ask after looking at the SIBO antibiotic relapse rates, side effects, and the cost of purchasing Xifaxan. Yes, you can definitely treat SIBO without antibiotics and in many cases, this may be a better strategy over the long term.

When you realize that most people will relapse after a successful course of antibiotics it makes sense to consider treating SIBO naturally and taking a more gradual approach.

There are a few treatment options that you might find to be effective:

Remember that while some treatments work for others, they may not be the best for you. Everyone has a different health history and underlying causes contributing to their issues. It’s best to consult with a doctor for specialized advice.

Concluding Thoughts on SIBO Antibiotics

If you’re thinking about taking SIBO antibiotics like Xifaxan, know that they can work effectively and quickly. However, a course of Xifaxan is very expensive and you may still have side effects. Also, remember that there is a chance you may relapse once you stop taking the antibiotics.

If you are someone who is dealing with a stubborn case of SIBO- and willing to spend the money on Xifaxan- it can be a good option. On the other hand, if you don’t want to spend as much money and want to take a gentler long-term approach, using a natural treatment protocol may be your best bet. Using herbal antibiotics, the elemental diet or long-term diet changes can be just as effective as antibiotics.

If you want to review all the different treatment strategies used for SIBO before making a decision see this overview.

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