Fluoroquinolone antibiotics were the most commonly prescribed antibiotics in the United States from 1995 until 2016.

Fluoroquinolone antibiotics (herein referred to as FQ’s) include: ciprofloxacin (Cipro), norafloxacin (Noroxin), levofloxacin (Levaquin/ Quixin), gatifloxacin (Tequin), moxifloxacin (Avelox), and ofloxacin (Ocuflox/ Floxin/ Floxacin).

You might be prescribed FQ’s for: urinary tract infections, pneumonia, bronchitis, sinusitis, bronchitis, and/ or food poisoning.

If you or someone you love has taken even one cycle of these antibiotics, I urge you to keep reading as the resulting toxicity from FQ’s can be permanent. You will discover that some rare disorders can be attributed to FQ side effects, how FQ’s work, and what you can do if you are a victim of fluoroquinolone toxicity.

Doctor Gerard Guillory Presenting Fluoroquinolone Toxicity and My Family

I recently heavily researched FQ’s because two of my siblings suffer from EDS (Ehler’s Danlos Syndrome). EDS is a connective tissue disorder that causes overly flexible joints,

stretchy skin, and poor wound healing. My sister, Susan, became so weakened from her hypermobility EDS that she sought treatment overseas in Paris where she could receive better care.

On a phone call one afternoon, I listened to Susan describe her symptoms of joint pain, gas, bloating, diarrhea, and abdominal pain. That sounds like SIBO (Small Intestinal Bacterial Overgrowth), I told her. She shared this theory with her doctors in Paris and, to my surprise, they did not know what SIBO was. Susan then invited me to Paris to give a talk to a community of interested doctors about SIBO.

In preparation for that talk, I came across a podcast by Dr. Alena Guggenheim. In the podcast, Dr. Guggenheim discusses SIBO as it relates to other rare diseases like POTS (Postural Orthostatic Tachycardia Syndrome) and MCAS (Mast Cell Activation Syndrome). When I heard that, a light bulb went off.

A Doctor’s Hunch

Avid readers of our blog know that I believe M.D. should stand for “Medical Detective” and this is the perfect example. I started to connect some dots. POTS, SIBO, MCAS, and EDS were little heard of when I went to medical school over 30 years ago. But now we see them more and more. So, what could they all have in common? My hunch was fluoroquinolones.

I recalled how there is a well-documented theory that Cipro caused Gulf War Syndrome in many of our military personnel. These veterans were prescribed Cipro to protect them against Anthrax. They came back home complaining of chronic multi-system debilitating diseases like: fatigue, muscle pain, cognitive problems, rashes, and diarrhea.

What Makes Fluoroquinolones so Dangerous?

Fluoroquinolones exert their antibacterial effects by damaging bacterial DNA and preventing it from unwinding and duplicating. When bacterial DNA cannot replicate, they die off.

Bacterial DNA is similar to mitochondrial DNA. As you recall from middle school science class, mitochondria are tiny organelles within every cell of the human body that originated millions of years ago when bacteria merged with cells of higher organisms. Mitochondria are the power generators of the cells. If they are not working, you are more likely to be fatigued. If FQ’s damage bacterial DNA, they likely also damage mitochondrial DNA. Studies show that FQ’s cause mitochondrial dysfunction mammalian cells.

It has also been suggested that oxidative stress underlies the many side effects of fluoroquinolones. Fluoroquinolones reduce the activity of superoxide dismutase (SOD), which is one of the most important antioxidant enzymes in the body. Oxidative stress further disrupts mitochondrial function, damages cellular function, and could very well explain why fluoroquinolones are toxic to the liver, kidneys, heart, connective tissue, and nervous system.

A final consideration when it comes to the mechanisms of fluoroquinolone toxicity is the depletion of magnesium inside cells. Magnesium is required for more than 300 enzymes to work in the body, and it has been proposed that fluoroquinolone-induced magnesium deficiency may be why these antibiotics trigger the onset of insulin resistance and type 2 diabetes in some people.

The FDA Acknowledges Fluoroquinolone Toxicity

FQ’s are so harmful that the FDA recently came up with its very own name for those impacted by its side effects. The amount of people who exhibited side effects like: tendinitis, tendon rupture, peripheral neuropathy, kidney damage, liver damage, gastrointestinal issues, and prostatitis were undeniable. The FDA finally established FADS (Fluoroquinolone-Associated Disability Syndrome) to acknowledge them

Now, at this point you might be wondering was Susan ever on an FQ? Yes. And, remember how I told you that two of my siblings suffer from EDS? My brother went through a cycle of FQ’s as well. Could it be a coincidence? There is still more to consider…

Fluoroquinolones and Complex Disorders

The list of devastating side effects from fluoroquinolone antibiotics is long. Fluoroquinolone toxicity manifests differently in every patient, and it is likely that many patients are labeled with other disorders without recognizing the role of the antibiotic.

As may be the case of my brother and sister, fluoroquinolone toxicity might be implicated in Ehlers-Danlos Syndrome, Postural Orthostatic Tachycardia Syndrome, and Mast Cell Activation Syndrome, to name a few.

Postural Orthostatic Tachycardia Syndrome (POTS) is a condition of disrupted blood flow, such that people experience a racing heart, dizziness, and other symptoms when standing up. POTS involves dysfunction of the autonomic nervous system, including the sympathetic and parasympathetic systems. The precise cause of POTS is not known, but it often develops after a viral illness, infection, hospitalization, trauma, or head injury. Fluoroquinolones cause neurotoxicity, and case reports often cite autonomic dysfunction as side effects. How many people with POTS were treated with these antibiotics before its onset?

Mast Cell Activation Syndrome (MCAS) is a condition that has only been recognized since 2007. It involves the excessive and inappropriate release of histamine from mast cells, leading to a wide range of baffling and often debilitating symptoms. Researchers think that MCAS might run in families, but they don’t know exactly why. It can develop at any age and usually comes on after an illness or stressor. Studies in animals show that fluoroquinolones trigger mast cells to release histamine. This video from the National Institutes of Health highlights a case of a man who developed MCAS after a case of food poisoning. Was he treated with fluoroquinolone antibiotics?

When it comes to Ehler’s Danlos Syndrome (EDS), it has been established that FQ’s are well known to cause tendon rupture, tendinitis, and other damage to the joints and connective tissue. However, EDS patients might be more susceptible to these side effects. There is no scientific evidence that fluoroquinolones cause EDS (it is thought to be inherited though there has not yet been a gene discovered for the 90% of EDS patients with the most common form – hypermobility type). It’s time to consider: how many people with EDS have been treated with quinolones?

Fluoroquinolones and SIBO

There is one more complex and increasingly common condition that deserves mention in relation to fluoroquinolone toxicity: small intestinal bacterial overgrowth (SIBO). SIBO is a condition marked by the excessive growth of bacteria in the small intestine. Symptoms include bloating, flatulence, abdominal pain, diarrhea or constipation, and whole-body symptoms like fatigue, mood changes, joint pain, and skin disorders.

There is a long list of potential causes of SIBO, many of which relate to an impaired mobility of the gastrointestinal tract. When the contents of the small intestine do not move through quickly enough, bacteria have more time to flourish. This is why autonomic nervous system dysfunction, opioid medications, and hypothyroid are associated with an increased risk of SIBO.

Nobody is talking about fluoroquinolone antibiotics causing SIBO, and I am not aware of any research studies on this subject. But here is what I think: we know that fluoroquinolone antibiotics damage the connective tissue and the nervous system. If they damage the enteric nervous system (the nerves that control the muscles of the intestinal tract), this could damage the migrating motor complex (the waves of contraction that push contents through the intestines), which would, in turn, slow down motility in the gut. We know that slowed gut motility allows for bacterial overgrowth and SIBO.

One of the highest profile thought leaders in SIBO research, Dr. Pimental of Cedars-Sinai Medical Center, claims that SIBO most often develops after a bout of food poisoning. I would add that FQ’s are commonly used to treat food poisoning. Does SIBO develop more frequently in patients who have had food poisoning and been treated with antibiotics? For me, that is one of the many burning and unanswered questions.

Fluoroquinolones and Genetics

Fluoroquinolone antibiotics are metabolized by an enzyme in the liver called cytochrome P4501A2 (CYP1A2). CYP1A2 is a critical detoxification enzyme, required to metabolize at least 100 known prescription medications and environmental toxins. How active CYP1A2 is in any given person is highly dependent on genetics.

Some people have genetic variations (SNPs) that dramatically slow down the activity of the CYP1A2 enzyme. If you are one of these people, fluoroquinolone antibiotics will metabolize more slowly and build up to toxic levels more quickly. Most people do not know what genetic variations they carry, much less how those genetic variations might influence their ability to tolerate fluoroquinolone antibiotics. I am not aware of any studies that have looked at this, but it would be interesting to see how many people with fluoroquinolone-associated side effects also have genetic variations in CYP1A2.

Forging a Path to Recovery

Knowing that fluoroquinolones cause oxidative damage, mitochondrial dysfunction, and

mineral depletions at the cellular level can inform us of new strategies to support recovery. For example, a recently published case study showed that low-dose naltrexone (LDN) led to dramatic improvements in a woman with severe POTS, MCAS, and SIBO. Quercetin might hold promise in supporting mitochondrial and cellular health after taking fluoroquinolones. Because of the need for additional antioxidant, immune, and neurological support, I might consider cannabidiol (CBD) oil in some patients.

In doing research for this article, I found a local website with some great information called FloxieHope. There is also a Facebook group called Fluoroquinolone Toxicity Group. I am not affiliated with these pages.

I am proposing what might sound like a revolutionary idea—that the side effects of antibiotics like Cipro and Levaquin might be contributing to increased numbers of people with complex and debilitating disorders—disorders like EDS, POTS, MCAS, and SIBO. The FDA as mentioned earlier describes a new syndrome resulting from fluroquinolone toxicity. I am also proposing that the best way to help these people is to think outside the box and to consider nutritional and integrative approaches.

You will not find these theories in a medical textbook (yet), and my more conventional-minded colleagues might meet me with resistance. Still, I am proposing these ideas because I want to find the best way to help my patients. I see a considerable number of patients in my practice with SIBO, and I am increasingly aware of these other rare and complex conditions. If more research establishes a connection between flouroquinolone toxicity and these other disorders, I would suggest that these antibiotics be reserved for severe, life-threatening infections when there is no safer alternative. If we can get to the root cause of the problem, we can find treatments that can change people’s lives forever.

About The Care Group

At the Care Group PC, we promote optimum wellness by providing an individualized, functional medicine approach to address root causes rather than simply treating symptoms. We help patients with a wide range of issues including autoimmune/inflammatory disease, digestive disorders, hormone imbalances, and mood disorders.

Schedule an appointment today by calling 303.343.3121​

Correction: the original version of this article stated that fluoroquinolone antibiotics were “the most commonly prescribed antibiotics in the United States from 1995 until 2016.” In fact, they became the most commonly prescribed antibiotics between 1995 and 2002, were the most commonly prescribed antibiotics for uncomplicated urinary tract infections through 2011, and continued to be the most commonly prescribed antibiotics in hospitals through 2012. A 2017 CDC report states that fluoroquinolones and vancomycin continue to be the 2 most commonly prescribed in hospitals. We have updated the original statement to read that fluoroquinolone antibiotics were “some of the most commonly prescribed antibiotics between 1995 and 2016.”

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About The Care Group: We promote optimal wellness by providing an individualized, functional medicine approach to address root causes rather than simply treating symptoms. We help patients with a wide range of issues including autoimmune/ inflammatory disease, digestive disorders, hormone imbalances, and mood disorders. To learn more about our practice, click here.

About the Author: Dr. Gerard Guillory, MD is Board Certified in Internal Medicine and has published two books on Irritable Bowel Syndrome (IBS). In 1985, he opened The Care Group, PC. Today, his clinic is a Primary Care facility that is a hybrid of functional and traditional medicine treating patients with digestive disorders, autoimmune disease, and other conditions. You can learn more about Dr. Guillory here.