Could hydrogen sulfide (H2S) be driving some of your chronic floxing symptoms?  Evidently it is in a subset of individuals who are chronically floxed.

Table of ContentsHydrogen Sulfide


Chronic floxing is ridiculously heterogenous. Outside the single incident of a person taking the Fluoroquinolones (FQ’s) themselves, there is no single mechanism, and there is no single trajectory when it comes to floxing. The drug can wreak its damage in multiple ways and cause an untold number of problems.

I do consider one of my obligations to report possible connections that are literally stumbled upon as we navigate the dark corridors of FQAD.  Whether these connections are strong or weak, these bits of data give us more information that could help some people deal more positively with the symptoms they experience. Obviously, these connections will only apply to a sub-set of individuals and not a majority, but they can be significant for some.

I report this data for information only to spawn further investigation and maybe the impetus for discussions with your trusted medical provider.  Reading this article assumes that you agree with the obligatory disclaimer.

Hydrogen sulfide has emerged as an issue in some chronically floxed individuals.

The Gut

It seems that chronically floxed folks generally experience some degree of gut related symptoms that run the gamut from mild to severe. For example, alternating constipation, diarrhea, bloating and functional dyspepsia (where folks experience upper GI discomfort soon after meals), are some of the more common complaints. Also, many report mild gastrointestinal discomfort but not any significant pain or dysfunction.

The bio diversity of gut bacteria is now considered much more important than it was years ago.  As we know the FQ’s are atomic bombs to the human body and damage through several different avenues.  Like the atomic bomb dropped on Hiroshima, the FQ’s the damage by outright destroying the gut microbiome through depletion in the short term, and epigenetically altering the bacterial composition in the long term, which allows the symbiotic state to cease functioning effectively.

I know that all antibiotics (actually many pharmaceuticals and non-pharmaceuticals alike) can damage the microbiome.  What makes the FQ’s so insidious is that they damage the microbiome and also impact other gut functionality as well, such as affecting motility via mitochondrial dysfunction.  So, the FQ’s can deliver a one, two punch to the digestive tract.

The combination of strains of bacteria in the human gut are as unique as each person’s fingerprint and it appears that disruption in that population can have severe consequences in some individuals, even in small amounts.  In some, these minor disruptions seem to fly under the radar scope therefore not creating any suspicions.

Symbiotic Relationship

From my own personal research I have learned that there are about 1000 different strains of microflora that could end up populating your gut, give or take a few hundred. Most individuals areGut Bacteria inoculated with around 150 core strains (not including subspecies) of this larger.  The exact amounts differ slightly depending on which expert you follow but you get the idea. This inoculation of bacteria primarily occurs during the birthing process.

This bacterial cocktail become unique to you over time and some experts believe these colonies of ‘probiotics’ become about as unique as your fingerprints.  It is theorized that this adaptation happens when DNA in the bacteria mutate to link to the environment in your colon.  More simply, they adapt to you in order to survive by providing you with nutrients that in-turn insure their survival in a true symbiotic relationship.

Viewing our gut microbiome this way, one can understand how devastating antibiotic use, especially FQ usage, can be to the overall health of an individual. Also using this perspective, one can see that, even though some bacteria are considered good ‘probiotics’, they may not be ‘good’ for you as they lack the history of being ‘seeded’ by mother and then subsequently mutating to your environment.

Enter Hydrogen Sulfide

Human gut microbes perform many metabolic functions that our own bodies cannot carry out.  They assist with the breakdown of food and their associated by-products contribute to our health. Danger Hydrogen SulfideMost gut microbes are present within the large bowel but in many individuals, due to motility problems or other factors, these colonies of bacteria can become overgrown and move up the digestive tract.  In this scenario, even good bacteria can behave bad. The overgrowth of bacteria in the gut inevitably leads to an overproduction of by-products which can become toxic in certain doses.   One of these by-products is Hydrogen Sulfide or H2S.

H2S, like many things, is produced by normal cells and is involved in regulation of blood pressure, neuro-transmission, muscle relaxation and levels of inflammation.  Internally produced H2S plays a role in regulating blood pressure, body temperature, vascular smooth muscle, cardiac function, blood flow to the brain, and is an important modulator of the hypothalamus-pituitary-adrenal axis.

In the ‘normal’ person H2S is cleared quite efficiently, being broken down by enzymatic activity and released through the lungs.

However, when the mitochondria are poorly functioning, as they are in many chronically floxed folks, H2S can become quite toxic.

When in excess (what constitutes excess H2S can be quite arbitrary depending on the individual) H2S acts as a mitochondrial poison inhibiting many enzymes involved in oxidative phosphorylation, affecting the levels of mitochondria of energy by reduction of ATP (source).

Dr. Sarah Myhill, MD says that besides hitting the mitochondria (mito’s) very hard, excess H2S also interferes with oxygen transport in red blood cells, inhibits immune cells such as CD8, T cells, and Natural Killer cells, impacts the hypothalamic-pituitary-adrenal axis, and possible affects levels of glutathione.

As I have pointed out before, the FQ’s target and damage mitochondria via Topoisomerase disruption. Mitochondria themselves resemble bacteria in many ways and some scientists believe these organelles descended from ancient eukaryotic sulfur-using microbes. Many chronic floxies that I know are poster children for mitochondrial dysfunction/disease, so it is no surprise that H2S could be very toxic to those with poorly functioning mito’s.

Dave, Aren’t We Talking About SIBO?

That is a good question.  Yes, but we are looking at it in a more specific scope.  According to studies, SIBO is a very heterogeneous syndrome.  In other words, it can have very broad symptoms and implications (source). In our case SIBO, caused by floxing and compounded on a mitochondrial dysfunction backdrop, is pretty complex. A while back I wrote and article about SIBO, you can find it here.  There is a lot of good information to be found on SIBO, but the opinions on causation and treatment can be very complex.  Anyway, more than likely the reason for the excessive H2SWhat is Floxing? production is SIBO caused by dysmotility, microbiome disruption, or both.

A healthy body has several different ways of preventing SIBO. Chris Kresser M.S. L.Ac, functional medicine expert, states that these include gastric acid secretion (maintaining an acidic environment), waves of bowel wall muscular activity, immunoglobulins in the intestinal fluid, and a valve that normally allows the flow of contents into the large bowel but prevents them from refluxing back into the small bowel. (This is called the ileocecal valve because it’s located between the ileum, or terminal end of the small intestine, and the cecum, a pouch forming the first part of the large bowel.)

When functioning normally the small bowel plays an important role in digesting food and absorbing nutrients. It is also an important part of the immune system, containing an impressive network of lymphoid cells (cells of the immune system that help fight infections and regulate the immune system).

As I mentioned earlier, the normal (beneficial) bacteria that are an essential part of the healthy small bowel also perform important functions. These beneficial microorganisms help protect against bad (i.e. pathogenic) bacteria and yeast that are ingested. They help the body absorb nutrients, and also produce several nutrients (such as short chain fatty acids) (it also appears that the fatty acid metabolism is somehow targeted by FQ’s I will write an article on this in the future) and vitamins like folate and vitamin K. These bacteria help maintain the normal muscular activity of the small bowel, which creates waves that move the intestinal contents, like food, through the gut.

There are many ways that this complex system gets disrupted or damaged by FQ’s.  To be blunt, sometimes this is permanent damage that will require periodic or even ongoing treatment.  I will briefly touch on this towards the end of the article.

How to Get Tested for SIBO (Or Should I?)

Breath Testing: Breath testing is a non-invasive test that is used fairly frequently as a way to diagnose or rule out SIBO. The test works by testing for the presence of hydrogen or methane in the breath at specific intervals after a person drinks a liquid containing a sugar solution, such as glucose or lactulose.  Many gastroenterologists can do this testing in their offices. 

Despite its wide use, concerns about the validity of breath tests for SIBO have been raised. One of the biggest concerns is the fact that the test yields too many false positive results, particularly for people who have a rapid transit time of food through the digestive system, or false negative results, most likely in people who have gastroparesis (slow emptying of the stomach). In addition, there is no consensus on the best protocols for performing the test, nor is there a consensus on exactly what amounts of gas present in the breath constitutes a positive test result. Nevertheless, the simplicity and safety of the test are the primary reasons why this is the most popular way to test for SIBO.

I have heard of folks who cannot afford to get the lactulose testing. There are reportedly home test kits for this but I do not have any feedback on the bad or good regarding these.

Jejunal aspiration: More invasive, but considered more accurate for diagnosing SIBO than the breath test, is a test called “jejunal aspiration.” This procedure takes place during an upper endoscopy procedure and requires that a sample of fluid be taken from the middle section of your small intestine. The sample is then cultured and evaluated for the presence of bacteria.Jejunal aspiration is not generally used. Its downsides are that it is costly, time-consuming, and while generally considered safe, still carries more risks than a breath test.

Medication Trial:  A fairly common way, and the most used, was for a medical practitioner (naturopath, functional, or traditional) to assess the presence of SIBO via consultation and symptom review and experiment with a therapeutic trial  of an agreed upon treatment regimen.  Obviously, some sort of symptom relief would therefore suggest that SIBO was present.

I have interacted with several floxies over the years who have not had any outward signs of digestive issues but had to have an antibiotic or other antimicrobial for other health reasons and reported a lessening in some of their non-digestive floxing symptoms.  Although antibiotics (natural and synthetic) can have other effects in the body such as anti-inflammatory mechanisms, one could argue that H2S was driving symptoms in a stealth manner without them knowing about it.

Testing is controversial.  I, personally, had a lactulose breath test several years ago and failed it miserably.   Some have had symptoms but passed the lactulose test and still responded well to some form of treatment.

How is This Affecting Some Chronic Floxies?

I collect real world data on floxing from sufferers. I have done this for many years. Over time patterns seemingly appear amongst groups of individuals.  In one such pattern, some chronic floxies are finding that their unpleasant symptoms are being exacerbated by H2S.  Some of the more pronounce symptoms commonly reported are:

More commonly:

  • Chronic Fatigue (And it can get severe)
  • Tired but wired feeling (seen frequently with chronic fatigue)
  • Post exertional malaise and weakness
  • Cognitive difficulties (brain fog), interestingly in particular some people have reported aphasia (dysphasia) like symptoms
  • Breathing difficulties (air hunger with normal SpO2 and cardiac function)
  • Achalasia and other digestive tract motility issues
  • Abdominal, arm, and leg weakness

A Little Less

  • Myalgia
  • Palpitations
  • Neuropathy exacerbation
  • “Tweaked” Nervous system ( Increase in tinnitus, insomnia, etc…)
  • Weight loss and symptoms related to vitamin deficiencies (malabsorption)

General mention but not common to all:  Photophobia, Dizziness, specific pain complexes (such as chest, arms, shoulders, or hips). This is not an all-inclusive symptom list as symptoms can vary.


Interestingly, and I wouldn’t completely hang my hat on this, but I am also noticing a loose correlation between severity of symptoms in floxies who have certain single nucleotide polymorphismsGenetics (SNPs) when exposed to and overabundance of H2S.  From 23andMe data those with more homozygous SNP’s in the ATP, COX, and NDUF sections seem to have more severe fatigue symptoms than others.  H2S at toxic levels inhibits cytochrome c oxidase, a key component of the mitochondria respiratory complex IV (source).  Also, CBS mutations may also play a role in some. Again, this is a loose correlation and more data needs to be extrapolated to hang our hats on specific genes, but there is enough of an occurrence to warrant a mention and point to an investigative follow up if you suspect H2S as a culprit.

So, in retrospect, it appears that in some chronically floxed folks the gut is producing too much H2S and driving negative symptoms.   In most floxies who were affected by this, their mitochondria are believed to be moderately to severely dysfunctional. In some of the floxies the corresponding gut symptoms were very noticeable and on others hardly at all.  What is remarkable here is that there is no ‘one size fits all’ symptom pattern for excessive H2S production and buildup. There are many unknowns about H2S, including the amount of gut H2S the normal person can tolerate.  Some folks had severe symptoms while other had mild symptoms, but all were helped to some degree or another by bringing the H2S under control.

Probiotics, Good or Bad?

That’s a good question. Over the years I have talked to many floxies that cannot take probiotics for one reason or another.  It appears that in some floxies probiotics drive an increase in H2S production and make their symptoms worse or it may drive some of their negative symptoms even without them knowing it.  This is because high levels of H2S are caused by an intestinal overgrowth (SIBO) of gram positive D/L lactate-producing bacteria.  So, for those plagued by H2S over abundance, strains of Lactobacillus bacteria, which are frequently found in those cheap and group packaged probiotic preparations (even expensive ones), could exacerbate lactic acid production and thus an over production of H2S as well.

It is important to note that not all Lactobacillus strains produce the undesirable D-Lactate.  For example, the Lactobacillus GG has been researched thoroughly and does not produce D-Lactate.  Unfortunately, many strains of the Lactobacillus family have not been thoroughly researched to determine their pros or cons when it comes to H2S production.  That is why I avoid those broad-spectrum “acidophilus” probiotics, especially the ones that are packaged with prebiotics.

How are People Treating This?

This is another area of wide opinion.  What we are basically looking at is primarily treating the SIBO.  However as we talked about above, SIBO is neither easy to quantify nor treat.  Treatments for SIBO run the gamut from diet, targeted probiotics, acids, enzymes, and antibiotics. The controversial part is whether some people, or most,  have crossed the point of no return so to speak and require continual or at the very least periodic treatment.   It appears that in most chronic floxing cases where the person is affected by H2S, some form of ongoing treatment or adaptation may be necessary.

There are experts that believe once the microbiome is damaged or obliterated beyond a certain point it cannot be repaired.  So, at what point do you cross the Rubicon to reach point of no return?  This, obviously, is an individual threshold that would largely depend on what type of damage/dysfunction is driving the dysmotility in the digestive tract.

In my particular case I am beyond the point of no return.  I have come to terms with the realization and work to maintain my gut continuously.  In my case I have neurological/mitochondrial and functional issues post floxing that cause motility problems and in-turn predispose me to SIBO.  Since I cannot correct the underlying pathogenic process that drives the dysmotility, I just do my best to maintain it.

Let’s briefly look at some of ways some floxies are treating this.


One thing that may be successful in mild cases is changing to a FODMAP diet.  FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, which are short chain carbohydrates and sugar alcohols that are poorly absorbed by the body, resulting in abdominal pain and bloating.

These carbs and sugars feed the bacteria in the small intestine that produce H2S.  Some folks have had a great reduction in symptoms by following the FODMAP diet. Things that should be avoided on a low-FODMAP diet are some vegetables and fruits, beans, lentils, wheat, dairy products with lactose, high fructose corn syrup, and artificial sweeteners.

Some folks try the FODMAP Diet for a while to see what symptoms abate.  Some have found that their digestive symptoms get better and their energy improves.  Others have found that digestive symptoms improve but fatigue does not.  The latter would probably indicate a more aggressive treatment is needed.   It is important to note that a FODMAP diet will not cure dysmotility but instead favors bacteria in the gut that do not produce H2S as a byproduct.

You get more information about the FODMAP diet here.

The FODMAP diet along with probiotics seemed to help those suffering from milder symptoms, while some others felt relief from a Stoneage diet. Personally, for me, I have found the FODMAP diet easier to follow post floxing than the Stoneage diet.

Another diet that has been reported to have limited success is an intermittent fasting diet.  I have no experience with this diet, but you can find more information here.


Some of the individuals that I have interacted with that have had success improving their symptoms using probiotics usually go strain-specific and avoid common probiotic groupings.  There are some exceptions to this, that I will point out.   The idea behind treating H2S and SIBO with probiotics is to populate the small intestine with strains that do not produce lactic acid and subsequently H2S.  This easier said than done.  Sometimes finding strain specific or single strain probiotics is difficult and expensive.  Often, probiotics are packaged with prebiotics which can be a big no-no for some people (I explain this shortly, below).  Plus there is a plethora or (mis)information floating around out there pro and con about various probiotics.  Even though there is a lot of hype, there does seem to be some evidence that suggests probiotics can be beneficial for some individuals in changing their microbiome.

The bad news is that, it appears that those who have seem to benefit from probiotics seem to have to use them almost continuously.  This is probably due to an underlying dysmotility issue which helps drive the SIBO and in-turn the H2S.  There is a chance, in some, that the gut may get properly re-seeded so to speak and continual probiotic inoculation may not be necessary.   Anyway, some strains that have been reported to be helpful are:

  • Lactobacillus GG
  • Lactobacillus Reuteri
  • Bifidobacteria infantis 35624
  • Lactobacillus plantarum 299V – Some folks have has success with the nonpedigree strain of L. plantarum
  • Bifidus Lactis
  • Bacillus Indicus (HU36TM)
  • Prescript Assist – This is one of the exceptions that I mentioned earlier. Prescript-Assist is a probiotic formula containing 29 different bacterial species. Unlike most probiotics, these bacterial species aren’t lactic acid bacteria. Instead, they represent soil-based bacteria. There is some controversy surround the use of soil-based probiotics.  This article is not designed to explore that controversy, so you would have to do your own research or consult a professional.
  • Saccharomyces boulardii – Not a probiotic in the traditional sense but instead a beneficial yeast. It fights off pathogenic strains of bacteria and some research shows it reduces inflammation.  It does not colonize the gut, so it needs to be taken continuously and with probiotics. There is some controversy surround the use of probiotic yeasts, but many have safely taken S. boulardii without any problems.  Again, this article is not designed to explore the controversy so do your own research or consult a professional.  Again, I do know several folks who have used this very successfully, especially with those suffering from IBS-D associated with their SIBO and H2S.
  • Kefir – This one is a conundrum. Interestingly kefir does not form D-Lactate according to some experts.  One would have to experiment with the various brands, types, etc…

Unfortunately, yogurt has a bad track record of producing high concentrations of D-Lactate.

Important note about prebiotics:  Many, not all, who I reacted with when writing this article had to avoid using probiotic brands that contained prebiotics such as FOS, MOS, or other integrated prebiotics.  Prebiotics, although good in certain circumstances, can feed the bad bacteria that are causing the H2S problems.  Evidently using too much prebiotic can hamper find that ‘sweet spot’ necessary to switch microbiome makeup. It is hard to find many probiotics, or even S. boulardii for that matter, that are free of prebiotics.  Because of this, I have integrated links to products that I am aware of. There may be more products out there sans the prebiotics you’ll just have to look hard for them.  If you find some, let me know and I will use the data to share with others.

Enzymes and Acids

Over the years I have received several reports of either suspected or documented pancreatic insufficiency.  In addition, pancreatic insufficiency is found to be increased as we age even in people without any known gastrointestinal disease or diabetes. Whether this is the case or not with a larger pool of floxies, some folks have been helped with the addition of digestive enzymes.  Digestive enzymes are essential for quick and efficient digestion of foods, so they cannot be fermented downstream and contribute to the H2S situation. There is a plethora of digestive enzymes on the market.  Personally, I have had pancreatic issues post floxing and I take digestive enzymes, one of my personal favorites can be found here or here.

Stomach acid is essential for sterilizing the stomach and upper gut.  This low stomach acid or hypochlorhydria can be caused by numerous factors, including antacids such as H2 Blockers, PPI’s and other pharmaceuticals and aging.  Since hydrochloric acid helps your body to break down, digest, and absorb nutrients, low acid can contribute to bacterial overgrowth.

I was always in a catch 22 situation post floxing.  For me floxing did something that started me having bouts of gastritis.  For a while I saw an alternative practitioner who told me my problem was due to low stomach acid and tried me on apple cider vinegar, betaine HCL, and other acid increasing techniques.  These treatments were abject failures causing me great distress. Later, I saw a gastroenterologist who, through testing, showed I was producing too much acid mainly due to gastroparesis which was caused by the mitochondrial dysfunction.  For me, my stomach was holding on to food too long thus overproducing acid.   I was forced to take something to lower the acid.

Nonetheless, some folks have been helped by taking supplements to help raise the level of stomach acid.  It is important to work with a professional on this one.

Natural Herbal Antimicrobials

When the problem is more severe, stubborn, or been present for a long time turning to a natural antimicrobial might be the next step.   It is my opinion that those who work with a knowledgeable functional health provider have a better overall chance of success when choose the right combo of natural antimicrobials.  There are a few studies that have shown that herbs can work just as effectively as pharmaceuticals for some(source).

Another observation is that, for some, success depends on the synergistic effect herbs have when used in combination with other herbs. This is because herbal antibiotics which are made from whole plants contain numerous different beneficial compounds instead of one isolated compound in regular antibiotics.  Also, herbal treatments usually need to be taken longer such as 4-5 weeks.

Some straight herbal treatments that have been used:

Below are combination formulas that have been proven effective for some. The dosage used was 2 caps twice a day for each product in one of the combination formulas.

There are other natural antimicrobials that need to be mentioned.  I am sure that I will miss some, these are just ones that people have mentioned to me or that I have tried myself:

MCT’s:  Medium chain triglycerides.  These are excellent as energy for some with impaired mitochondrial functioning.  The FQ’s are suspected to interfere and even damage genes involved with fatty acid oxidation.   Anyway, MCT’s have antimicrobial properties (source).

Olive Leaf Extract, (source).

Prescription Antibiotics, Seriously?

Despite our fear of ever using antibiotics again, many folks must for one reason or another. Ironically, several folks have mentioned to me that they feel a lot better when they took antibiotics for various reasons.   This phenomenon makes perfect sense if some of your post floxing symptoms are being exacerbated by an overgrowth of bacteria in your small intestine, since antibiotics are killing off the bacteria.

Let me throw in the caveat here that antibiotics require a prescription in the U.S. and many countries, so please consult your trusted medical professional for all decisions related to taking antibiotics.  Also, I am not advocating the use of antibiotics.  I do know several floxies that have purchased antibiotics and other pharmaceuticals without a prescription from here.  This is supplied as information only.  In addition, I believe tha this is a highly individual decision best left between you and your doctor.

I wish that I could say that individuals reported that only one course of antibiotics would cure them of this situation but alas that is not the case.   Antibiotics are a double-edged sword. For many they are the cause of the problem in the first place and although they can help some, antibiotics alone rarely cure SIBO in the long term.

It is possible that initial FQ antibiotic use in the first place, created a no-win scenario.

There are two antibiotics which are mainly used for treating SIBO: Rifaximin (Xifaxan) and Neomycin.  Note, that Neomycin is usually used with methane dominate bacterial species.  The reason these two are commonly used is because they are primarily non-systemic, meaning they mostly don’t get absorbed into the bloodstream and instead stay in the intestines, allowing them to kill bacteria residing in the intestines and not elsewhere.

Most floxies can tolerate Xifaxan according to reports, but I have had several reports of floxies not tolerating Neomycin.

Less frequently used is the systemic antibiotic Metronidazole (Flagyl).  Flagyl is sometimes chosen over Xifaxan because of the cost.  Flagyl has a so/so reputation for toleration at around 50%. It can cause some neurological symptoms via thiamine deficiency. I wrote an article about Antibiotic Use After FQ’s here.

Generally, doctors will prescribe these antibiotics for 10 to 14 day courses.

At, Dr. Siebecker (a leading expert on SIBO) gives these as some examples of SIBO dosage options. Keep in mind that there aren’t any established protocols for SIBO antibiotic dosages, so your doctor may prescribe something different1:

Rifaximin 1600mg daily x 10 days

Rifaximin 1200mg daily x 14 days

Rifaximin 1600mg daily + Neomycin 1000mg daily x 10 days

Rifaximin 1600mg daily + Metronidazole 750mg daily x 10 days

Oftentimes, a single round with one of these antibiotics doesn’t cure SIBO, especially in severe cases. When the first course doesn’t work, doctors will often prescribe another antibiotic or add another antibiotic to the treatment for another course.

I have had mixed reports of success using antibiotics for SIBO (H2S Treatment) from floxies.  Reports range from a miracle cure to no help at all and several in between, where the antibiotic will help with some symptoms and not others. Some have had to take a non-systemic antibiotic like rifaximin, followed by a systemic antibiotic like a short dose of vancomycin. I think the reason for this has to due with gut permeability and the fact that some of the bacteria actually get deeper into the lining of the tissues surrounding the digestive tract.

Going Down the Rabbit Hole or Can We Recover?

Antibiotics are often used by both alternative and traditional doctors to treat SIBO. However, studies show that despite treatment with antibiotics, recurrence develops in almost half ofRabbit Hole all patients within one year. One study comparing treatment with rifaximin (the most commonly used antibiotic for SIBO) and botanical antimicrobials showed slightly better outcomes with the botanical protocol, but still with successful treatment in close to only half of all patients after one course of treatment.

Ironically, taking FQ’s in the first place was the trigger that started this mess for a lot of people.

Microbiology expert Jeroen Raes recently told listeners his Brussels TEDx talk on the subject of SIBO that “If you get a normal dose of broad-spectrum antibiotics, some of you will recover, in terms of gut flora, after a few weeks. For some of you, it will take months. For some of you it can take over a year for your gut flora to become ‘normal’ or to return to what it was again. And for some people, they never recover. They have permanently altered their gut flora.”

Keeping this in mind, I have contact with a lot of people that would suggest that the FQ’s do create a permanent case of dysbiosis in some. Either by permanently altered their gut flora or causing dysmotility via mitochondrial damage, neurological damage, dysautonomia, or a combination of several factors.

Furthermore, a lot of alternative medicine treatments that focus on addressing the underlying cause, or predisposing factor don’t work on floxed folks because the FQ’s caused a permanent situation.   I have found that many, not all, alternative practitioners are no better than their classical counterparts when it comes to understanding what the FQ’s can do to the human body.

Increasing Gut Motility or What Came First, the Chicken or the Egg?

There are many identified associations between SIBO and disease processes.  It would be safe to say that abnormalities in gut motility are probably the predominant driving force in H2S coupled with other factors on top, such as low acid, enzymatic insufficiency, and so on.

Did the FQ’s cause mitochondrial dysfunction or nerve damage which led to SIBO(H2S) over production?  Or, did the disruption of the microbiome cause the slow down then becoming reinforced via other factors?  Trying to figure out what comes first is like arguing the chicken or the egg scenario.

Either way, it seems safe to say that a slowdown is taking place.  Most individuals, who do not recover after a standard course of antibiotics, or botanical antimicrobial, or enzymes, or probiotics, may benefit from the addition of a prokinetic agent.  Prokinetics increase the muscular contractions of the small bowel. The migrating motor complex (MMC) is a cyclic and recurring pattern of motility that occurs in the stomach and small intestine.

Abnormal motility of the phase III “housekeeper” waves of the migrating motor complex in the small intestine may contribute to the development of SIBO in individuals with IBS (source).

Many practitioners recommended to take prokinetic agents immediately before going to sleep, since, while we sleep, our body is going through several detoxifying and repairing processes and this is also the time period where we experience the most MMC waves.

To be honest I do not have a lot of data on prokinetic agent use in floxies. Just a sparse handful of reports here and there.


Prokinetics fall into two categories:  Pharmaceutical and Natural

Pharmaceutical prokinetics include, Domperidone, Metoclopramide, Levosulpiride, Erythromycin, Tegaserod, Mosapride Citrate, Renzapride, and Prucalopride.

Pharmaceutical prokinetics can and do have many drawbacks.  First, and foremost is that most of them affect other parts of the body apart from the gut, acting act on chemicals that are important for regulating memory, mood, and behavior.  It is very imperative that you understand all the risks before using these drugs.   Of the drugs in this category domperidone has one of the lowest side effect profiles. Domperidone is widely available in every country in the world accept the U.S. which has more limited availability. In the United States domperidone is not yet FDA approved but it is currently available at select compounding pharmacies with a doctor’s prescription.

Natural prokinetics include, Ginger, Iberogast, Motilpro, Triphala, Rikkunshito, and Si Mo Tang.

It is important to realize that most natural and herbal medications are not regulated for purity and quality therefore it is imperative to buy quality products from a trusted proven source. This is only after you have equipped yourself with all the available information.

Also, while herbal formulas are generally safe, if you take prescribed medications, know that herbal supplements (especially in large doses) sometimes interact with your prescriptions causing other side effects. So, it would be wise to work under a doctor’s guidance.

To research these prokinetic substances in more depth you can follow this link here.

Cases Descriptions

Case #1

Bill, 58-year-old male, floxed for 12 years.  Bill suffers from the standard post FQ’s chronic floxing; some neuropathy, chronic fatigue, some digestive issues. His digestive issues began after floxing. And ranged from mild to moderate, mostly IBS-C with occasionally IBC-D, and he was using the Fodmap diet to control most of his digestive symptoms.  One day at the gastroenterologist’s office his doctor mentioned the lactulose test which Bill consented to take.  Bill failed the test miserably, showing an excess of H2S producing organisms.  Ironically, the doctor’s office wanted to start him on Cipro right away but obviously Bill said, “Hell no!”  Bill also refused Flagyl (Metronidazole) and instead he opted for a course of Xifaxan (Rifaximin) which luckily the insurance paid for after the doctor’s office jumped through some hoops documenting a FQ allergy.

Bill said the results of the Xifaxan were pretty astounding.  First thing that happened was that he got about a 20% increase in energy within a week of starting the xifaxan, which he said was a great improvement.  He also reported an improvement if brain fog and lessening of neuropathy symptoms and a moderate improvement in digestive issues.   Currently, he still watches what he eats and still follows the Fodmap Diet.  He takes 5-htp at bed to help with motility. Despite that, he still has to repeat the Xifaxan every six months or so, which my insurance covers with help from my Gastro doc.

Case #2

Gail, a 55-year-old woman floxed for 10 years.  Post floxing, she suffered from severe weakness and fatigue which included PEM and routine ‘crashing’ that would leave her bedridden or house bound. She had a history of gastrointestinal problems post floxing which included some mild diarrhea but severe constipation, non-specific abdominal pain, bloating, and gas. Certain carbs or sugars exacerbated her problems. She did have to have a cholecystectomy (gall bladder removal) post floxing. She was forced to have to use oral dicyclomine for an infection and noticed an improvement in her floxing symptoms, which initially puzzled her.  After discussing with her doctor her digestive symptoms, she received a lactulose test and results show H2S production.  She agreed to try a course of Flagyl (Metronidazole).

Gail initially got some stomach cramping and diarrhea from the Flagyl but decided to finish all the medication.  Amazingly, she reported a 50% reduction in fatigue and weakness.   Since the Flagyl she is eating a lower carb diet and uses Iberogast to help with motility.  She knows that she will probably have to use the Flagyl again in the future but is apprehensive about ever having to use antibiotics again.

Case #3

Lydia, a 38-year-old female was floxed for 6 years,   She described herself as moderately floxed and suffered from neuropathy, migraine headaches, fatigue, and digestive issues that included mild to moderate constipation and abdominal pain, both of which were intermittent, and self-limiting.  She sought help for her problems from a naturopath who determined from her symptoms that she had SIBO.

Lydia was prescribed a combination of oregano oil and Berberine.  She also used 5-htp and Ginger for motility.  Her treatment eased her digestive issues along with some of her fatigue and brain fog.

I want to thank the three floxies who allowed me to share their brief experiences.  I do have more and in the future I may add others experiences in correcting H2S as time permits.


It is very important to note, as mentioned earlier, that I have interacted with floxies who have not had any outward signs of digestive issues but had to have an antibiotic for other health reasons and reported a lessening in their floxing symptoms.  Although antibiotics can have other effects in the body such as anti-inflammatory mechanisms, one could argue that H2S was driving symptoms in a stealth manner without them knowing about it.

H2S can be quite detrimental to some individuals with mitochondrial disease/dysfunction brought about by the FQ’s.   Although this article covers a lot of information, I have barely touched the surface and did not cover areas such as attempting to heal the gut and the controversy surrounding L-Glutamine and floxies.  It is provided to be an impetus for further investigation or to spur conversations with your trusted medical provider.

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