Rifaximin – What It Is and When You Might Need It

Rifaximin is an oral antibiotic that stays mostly in the gut. Because it isn’t absorbed into the bloodstream, it works well for infections that affect the intestines. Doctors often prescribe it for traveler's diarrhea caused by Escherichia coli, for certain cases of irritable bowel syndrome with diarrhea (IBS‑D), and for preventing recurrence of hepatic encephalopathy.

If your doctor mentioned Rifaximin, they probably want to target a bacterial problem without exposing the rest of your body to the drug. That means fewer systemic side effects, but you still need to follow the dosing schedule exactly.

How Rifaximin Works

Rifaximin stops bacteria from making proteins they need to grow. By binding to the bacterial RNA polymerase, it blocks the production of new proteins, which kills the bacteria or stops them from multiplying. Since it concentrates in the intestines, it can clear the infection right where it lives.

Because it stays in the gut, it doesn’t affect most other organs. This also means it has a lower risk of causing liver or kidney problems compared with some other antibiotics.

When to Take Rifaximin Safely

Typical adult doses for traveler's diarrhea are 550 mg three times a day for three days. For IBS‑D, the usual course is 550 mg twice daily for 14 days. Always take the pills with a full glass of water and try to keep a consistent schedule.

If you miss a dose, take it as soon as you remember—unless it’s almost time for the next dose. In that case, skip the missed pill and continue as normal. Don’t double‑up because higher doses can increase side effects.

Common side effects include mild nausea, headache, and a temporary increase in stomach gas. Most people feel better within a few days. If you notice severe diarrhea, vomiting, or a rash, call your doctor right away.

Rifaximin can interact with some drugs that affect gut bacteria, such as other antibiotics or certain probiotics. It also reduces the effectiveness of oral contraceptives in rare cases, so use a backup method if you’re on birth control.

Pregnant or breastfeeding women should only use Rifaximin if the doctor says the benefits outweigh the risks. There isn’t enough data to say it’s completely safe, so discuss any concerns before starting.

Store the medication at room temperature, away from moisture and heat. Keep it out of reach of children, and don’t share it with anyone else—even if they have similar symptoms.

In short, Rifaximin is a gut‑focused antibiotic that can clear certain infections quickly and with fewer systemic side effects. Follow the prescribed dose, watch for any unusual reactions, and talk to your doctor about any other meds you’re taking. Doing so helps you get the most benefit while staying safe.