Rifaximin (Xifaxan) is an antibiotic that is typically used to treat traveller’s diarrhea and hepatic encephalopathy. It is also sometimes used in Irritable Bowel Syndrome to combat bloating and flatulence. Rifaximin may also be useful in treating small intestinal bacterial overgrowth. It is generally low in side effects and very little of the drug is absorbed into the bloodstream.
Mechanism of Action for M.E.
There exist several potential mechanisms by which Rifaximin may help ME patients. The primary mechanism of action theory involves Small Intestinal Bacterial Overgrowth (SIBO.) SIBO is caused when the healthy bacteria that grow in our large intestine make their way to our small intestine. This can result in a range of gastrointestinal symptoms.
In this study by Dr. Pimentel, a lactulose breath test was used to test for SIBO.
3/15 (20%) of controls tested positive for SIBO,
93/111 (84%) of those with IBS tested positive for SIBO,
42/42 (100%) of those with Fibromyalgia tested positive for SIBO.
Interestingly, the degree of somatic pain felt by the Fibromyalgia patients, “correlated significantly” with the amount of hydrogen seen on the lactulose breath test. Previous studies have linked the amount of hydrogen on the lactulose breath test with the amount of SIBO.
Another study mentioned that SIBO is often associated with higher levels of intestinal permeability. This study therefore examined Fibromyalgia patients for intestinal permeability and found that they experienced significantly higher levels of it than the control group.
Rifaximin may also benefit ME patients as it balances the gut flora. In vitro, Rifaximin inhibited 90% of the 536 strains of anaerobic bacteria tested in this study.
It should also be mentioned that Restless Leg Syndrome (RLS) patient’s who tested positive to SIBO found symptomatic improvement in this study.
Some ME patients take Rifaximin with the sole purpose of treating IBS. This meta-analysis concluded that there is “accumulating evidence” indicating that Rifaximin is beneficial to IBS patients.
Rifaximin for which ME Patients?
Some ME/Fibromyalgia patients get a hydrogen breath test performed prior to commencing SIBO treatment while others have the philosophy that they will test positive anyway hence testing is fruitless. Anecdotally, some ME patients with no gastrointestinal symptoms seem to improve on Rifaximin. There is also anecdotal evidence indicating that some ME patients’ symptoms improve whilst on the drug and return upon completing the course of Rifaximin. This is perhaps due to the SIBO numbers not being completely wiped out whilst on the drug and flourishing again when the Rifaximin is discontinued. A number of these patients continue to take Rifaximin intermittently or long term. The main symptoms Rifaximin seems to improve in ME patients include; gastrointestinal symptoms, fatigue and cognitive impairment. Anecdotally, a reasonable number of ME patients have benefited from Rifaximin for at least some period of time.
Usage amongst ME/CFS Specialists
Dr. De Meirleir uses Rifaximin on patients based on test results, including this dysbiosis test. He sometimes combines it with other antibiotics depending on test results and recommends the Rifaximin be followed by a 23 day course of the probiotic VSL#3
Dr. Teitelbaum believes that all ME/CFS patients be at least tested for SIBO. He writes about his theories of SIBO here.
Dr. Peterson seems to prescribe Rifaximin to a number of his patients with some taking the probiotic VSL#3 after the Rifaximin course.
Dr. Myhill recommends Rifaximin to some patients. Although she has a different dosing strategy to most, involving 200mg 3x a day for 3 days followed by a maintenance dose of 200mg daily. She also incorporates a hydrogen sulphide urine test to monitor progress. She elaborates on this here.
Several studies have indicated that the risk of developing antibiotic resistance to Rifaximin is low, especially when used for around 2 weeks, several times per year. Long term use of Rifaximin increases the possibility of building resistance to the drug.
Rifaximin is generally well tolerated and low in side effects. In a traveller’s diarrhea study, only 0.4% of patients had to discontinue Rifaximin due to side effects. In general, the most common side effects of Rifaximin tend to be gastrointestinal and include; nausea, flatulence and ascites. Other frequent side effects include; dizziness, fatigue and peripheral edema.
There is a slight discrepancy regarding Rifaximin dosage for ME patients. Some specialists recommend 400mg 3x a day for 7-10 days. Others recommend 550mg 2x a day for 8 days. As mentioned above, Dr. Myhill recommends a lower dose while others recommend a higher dose of 550mg 3x a day for 14 days.
Rifaximin can be very expensive. A US patient with ME reportedly spent $800 on a 2 week supply, fortunately for them, the Rifaximin was effective. Only some insurance companies cover the drug. The high cost of this treatment has caused many in the ME community to purchase this drug from one of many online pharmacies.
Many specialists specifically recommend the probiotic VSL#3 to be taken after finishing the Rifaximin course. This probiotic is expensive and is most effective when it remains in a cold environment. It is therefore commonly shipped either refrigerated or with an ice-pack.
My Experience with Rifaximin
I obtained Rifaximin from an Australian compounding pharmacy for a relatively cheap price. When starting most treatments, I like to start out with a low dose. The nature of Rifaximin meant that I started out at the maximum dose of a 550mg capsule, 3x a day and I continued with this dosing structure for my entire 2 week trial. Beginning on the 20th of October 2014, I took 1 capsule with breakfast, 1 with lunch and 1 with dinner. When I had ceased my 2 week course of Rifaximin, I commenced taking the probiotic VSL#3.
Ultimately, I didn’t gain any significant benefit from the Rifaximin treatment. I should stipulate that I do have gastrointestinal symptoms however these are much milder than many of my other symptoms. I experienced more vivid dreams while taking Rifaximin and I continue to experience these dreams of clarity, several days after stopping the antibiotic. I only realised post hoc, that dream vividness can be a side effect of Rifaximin. These clear dreams are in no way negative and as not much happens during my waking hours, it is nice to be ‘alive’ during the night. I also believe my Restless Leg Syndrome may have dissipated slightly while taking the Rifaximin although I am not confident of definitively drawing a cause-and-effect link in my case. I didn’t notice any negative side effects while taking the Rifaximin.