The first strange thing about Xifaxan is the prescription itself.
One patient takes it before departing on a vacation abroad. Another takes it for two weeks due to IBS making breakfast before work nearly impossible. The third stays on it long term after being hospitalized with hepatic confusion.
Same drug, three very different tasks.
Xifaxan contains rifaximin, an antibiotic which mainly stays in the gut and is rarely absorbed into the bloodstream. That’s why nobody gives it for a chest infection or an infected wound. It works where it’s supposed to be: the intestines.
Why would an antibiotic help IBS?
Patients sometimes describe IBS-D as an occasional loose stool, but for those living with it the reality can be vastly more disruptive.
You eat lunch and immediately start scouting the nearest bathroom. A 30 minutes train trip ahead is a brave endeavor. Morning coffee is a gamble you eventually stop taking.
Gut bacteria seem to contribute to some cases of IBS with diarrhea, although they’re definitely not the whole story. Xifaxan changes their activity in the intestine, helping some patients reduce abdominal pain, bloating, urgency and diarrhea.
The usual treatment is 550 mg three times a day for 14 days, after which the tablets are gone.
This always surprises patients who were expecting something to be taken long term. The idea is that things will get better after the course has ended. If it doesn’t, the same treatment can be tried again (up to two more times) to see if a repeat has an effect.
Results are not always spectacular.
One patient goes from 5 urgent movements a day to 1 or 2 manageable ones. Another feels bloated less often, but still has diarrhea. Someone else swallows all 42 tablets and feels completely the same as before.
This does not necessarily mean the prescription was pointless. IBS has many different possible drivers, and a treatment targeting gut bacteria will leave stress, food intolerances and especially hypersensitive intestinal nerves unaffected.
It has a more limited use for traveler’s diarrhea
Xifaxan can treat traveler’s diarrhea due to certain strains of E. coli. The usual treatment is 200 mg three times a day for 3 days.
The important word here is certain.
It’s not a good choice when the diarrhea comes with fever or blood in the stool, as these symptoms suggest an invasive type of infection. A drug that mostly stays in the guts may not be enough, and severe pain or vomiting require a doctor’s attention anyway. The same applies to persistent diarrhea which does not improve after 24 to 48 hours.
And no, it doesn’t act as a preventative measure for every holiday. Using antibiotics when they are not needed only encourages resistance, and a new side effect may turn up where none were expected.
Liver specialists have an entirely different reason to prescribe Xifaxan
When the liver is severely damaged, it may no longer be able to clear ammonia and other toxins from the blood. They can accumulate in the brain and cause hepatic encephalopathy.
It rarely announces itself in a dramatic way. The patient may sleep through an entire afternoon, become forgetful, have trouble following a conversation or suddenly act out of character. In many cases it’s the family that notices first.
Bacteria in the intestine are partly responsible for producing ammonia. Xifaxan modulates their activity in the gut, reducing the chance of another episode.
In this case, the usual dose is 550 mg twice a day (often for much longer than an IBS course). Many patients also take lactulose to help clear excess ammonia: the two drugs work in different ways and are often prescribed together.
Someone who takes Xifaxan to prevent hepatic encephalopathy should never stop because they feel well. Being clear-headed is in fact the reason they are on the medication in the first place.
Any new signs of confusion in a cirrhotic patient must be investigated, as constipation, infection, dehydration or internal bleeding can be the precipitating factors.
How does it feel to be taking Xifaxan?
Usually very benign.
It can be taken with or without food. Nausea is a common complaint when treating IBS with it. Headache, stomach discomfort, dizziness, constipation or change in bowel habits have been reported as well.
It may be challenging to determine whether a side effect is caused by Xifaxan, when the original diagnosis already involves abdominal pain and diarrhea.
An allergic reaction is also possible, especially in someone who has had one to another member of the rifamycin antibiotics. Swelling of the face/throat, difficulty breathing, hives or a severe rash require emergency intervention.
There is also the ubiquitous warning about C. difficile associated diarrhea that comes with every antibiotic. Persistent watery movement, fever or cramps during or after treatment should not be considered to be “the IBS coming back”.
Inform the prescriber if you take cyclosporine or warfarin. Cyclosporine increases the absorption of rifaximin, while patients on warfarin may need extra INR tests. Pregnancy and severe hepatic impairment also require a thorough discussion before starting treatment.
What should you expect from Xifaxan? That depends on the prescription. With traveler’s diarrhea it should help fairly quickly. For IBS-D it may continue to improve things after the two-week course, or only mildly. In liver disease the best result is measured in the absence of another episode of hepatic encephalopathy.
