From the Guidelines
Rifaximin is an oral antibiotic that should be used to treat traveler's diarrhea, hepatic encephalopathy, and irritable bowel syndrome with diarrhea (IBS-D) at specific dosages to minimize morbidity, mortality, and improve quality of life. For traveler's diarrhea caused by non-invasive E. coli, the standard dosage is 200 mg three times daily or 400 mg twice daily for 3 days, as supported by studies such as 1. For hepatic encephalopathy, rifaximin is prescribed at 550 mg twice daily to reduce the risk of recurrence, with evidence from recent studies like 1 showing its effectiveness in preventing recurrent HE and improving quality of life. For IBS-D, the typical dosage is 550 mg three times daily for 14 days. Rifaximin works by inhibiting bacterial RNA synthesis and is minimally absorbed from the gastrointestinal tract, allowing it to target intestinal bacteria while minimizing systemic effects, as noted in 1. This localized action makes it particularly effective for gut-related conditions and reduces the risk of developing antibiotic resistance. Common side effects include nausea, bloating, and headache, but the benefits of rifaximin in reducing morbidity and mortality, especially in conditions like hepatic encephalopathy, outweigh these risks, as seen in studies like 1. Patients should complete the full course of treatment even if symptoms improve before completion, and rifaximin should be taken with or without food, but consistent timing of doses helps maintain effective drug levels. Given the most recent and highest quality evidence, the use of rifaximin at the specified dosages is recommended for the treatment of traveler's diarrhea, hepatic encephalopathy, and IBS-D to improve patient outcomes 1.
Some key points to consider:
- Rifaximin's efficacy in treating traveler's diarrhea is well-documented, especially against non-invasive E. coli, as shown in 1.
- For hepatic encephalopathy, rifaximin has been shown to reduce the risk of recurrence and improve quality of life, making it a valuable treatment option, as supported by 1.
- The drug's minimal absorption and localized action in the gastrointestinal tract contribute to its effectiveness and safety profile, as discussed in 1.
- While side effects can occur, the benefits of rifaximin in reducing morbidity and mortality in targeted conditions make it a recommended treatment, as evidenced by recent studies like 1.
Overall, rifaximin is a valuable antibiotic for the treatment of specific gastrointestinal conditions, offering benefits in reducing morbidity, mortality, and improving quality of life when used appropriately 1.
From the FDA Drug Label
The efficacy of XIFAXAN given as 200 mg orally taken three times a day for 3 days was evaluated in 2 randomized, multi‑center, double-blind, placebo-controlled studies in adult subjects with travelers’ diarrhea.
XIFAXAN 550 mg orally administered three times a day for 7 days altered the pharmacokinetics of a single dose of an oral contraceptive containing 0. 025 mg of ethinyl estradiol (EE) and 0. 25 mg norgestimate (NGM).
Rifaximin has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections [see Indications and Usage (1. 1)]: Aerobic bacteria Gram-negative bacteria Escherichia coli (enterotoxigenic and enteroaggregative strains)
The uses of Rifaximin include:
- Travelers’ diarrhea
- Hepatic encephalopathy (HE)
- Irritable bowel syndrome with diarrhea (IBS-D)
The dosages of Rifaximin are:
- 200 mg orally taken three times a day for 3 days for travelers’ diarrhea
- 550 mg orally administered twice daily for hepatic encephalopathy
- 550 mg orally administered three times a day for 7 days for other conditions 2
From the Research
Uses of Rifaximin
- Rifaximin is used to treat various gastrointestinal and liver diseases, including:
- It is a broad-spectrum oral antibiotic with antimicrobial activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria 5
Dosages of Rifaximin
- The dosage of rifaximin varies depending on the condition being treated:
- For traveler's diarrhea, the recommended dosage is 600-1200 mg per day 3
- For hepatic encephalopathy, the recommended dosage is not specified in the provided studies, but it is mentioned that rifaximin is effective in improving neurologic signs and symptoms and reducing blood ammonia levels 4
- For irritable bowel syndrome, the dosage is not specified in the provided studies, but it is mentioned that rifaximin can reduce global IBS symptoms and improve bloating, abdominal pain, and stool consistency 6