Rifaximin: Uses, Dosing, Side Effects, and Practical Tips
Rifaximin is an antibiotic you take by mouth that mostly stays in the gut. Doctors prescribe it for traveler's diarrhea, hepatic encephalopathy prevention, and some cases of IBS with diarrhea (IBS‑D). Because it works locally in the intestines, it often has fewer systemic side effects than many other antibiotics.
How it helps: for traveler's diarrhea rifaximin cuts the duration of symptoms and can stop bacteria that cause watery diarrhea. For hepatic encephalopathy, studies show regular rifaximin lowers the risk of repeat episodes and hospital visits. In IBS‑D, short courses can reduce bloating, urgency, and loose stools for weeks in many people.
Common dosing and what to expect
Typical doses vary by condition. For traveler's diarrhea the usual adult dose is 200 mg three times daily for three days. For hepatic encephalopathy prevention doctors often use 550 mg twice daily long term. For IBS‑D the usual plan is 550 mg three times daily for 14 days, sometimes repeated if symptoms return. Always follow your doctor’s instructions — these are general examples, not a prescription.
Rifaximin starts working in a few days for diarrhea. For IBS‑D you may not notice full benefit until after the course ends. If symptoms persist or worsen after treatment, contact your healthcare provider.
Side effects, warnings, and interactions
Common side effects include nausea, stomach pain, gas, and headache. Serious allergic reactions are rare but possible — stop the drug and seek help if you get hives, swelling, or trouble breathing. Because rifaximin acts mostly in the gut, it has low blood levels and fewer drug interactions, but it can interact with certain medicines like cyclosporine and some anticoagulants. Tell your doctor about all medicines and supplements you take.
A warning: rifaximin can change gut bacteria. In rare cases this allows overgrowth of resistant organisms or Clostridioides difficile, which causes severe diarrhea. If you develop heavy diarrhea, fever, or black stool after treatment, get medical attention quickly.
Can you buy it online? Some reputable pharmacies supply rifaximin with a prescription. Be cautious with websites selling antibiotics without prescriptions — they might sell counterfeit or unsafe products. If buying online, choose a verified pharmacy, check for pharmacist contact, and confirm prescriptions are required.
Practical tips: take rifaximin with or without food the way your doctor tells you. Finish the full course even if you feel better. Store it in a dry, cool place out of reach of children. If you miss a dose, take it when you remember unless it’s near the next dose — then skip it and continue the schedule.
If you have liver disease, especially severe liver problems, talk to your doctor before starting rifaximin. For pregnant or breastfeeding people, discuss risks and benefits with your healthcare provider.
Questions for your prescriber: What dose and length should I use for my condition? Are there cheaper or generic options? What side effects should I watch for? Getting clear answers will help you use rifaximin safely and effectively.
Stay informed.
