Rifaximin 400 mg

Category- Allopathy

Medicine Highlights

Rifaximin Uses

Rifaximin 400 mg is an oral medicine belonging to the category of antibiotics and is used for the following indications: 

1. Inflammatory bowel syndrome associated with diarrhea 
2. Hepatic encephalopathy 
3. Traveler’s diarrhea 

Rifaximin side effects 

More Common  

1. Swelling in your hands or feet 
2. Nausea 
3. Headache, dizziness 
4. Tiredness 
5. Abnormal liver function tests. 

Less Common 

1. Watery diarrhea 
2. Diarrhea that does not go away 
3. Blood in your stool (poop) 
4. Severe stomach cramps 
5. Fever that starts after you start or finish the medicine  
6. Diarrhea that does not go away 
7. Blood in your stool (poop) 
8. Severe stomach cramps 
9. Fever that starts after you start or finish the medicine 

How Rifaximin works 

Sometimes, when your tummy hurts or you feel sick after eating or traveling, it can be because of too many harmful germs in your belly. These germs grow fast, make you feel bloated or give you diarrhea, and can even make your brain feel foggy if your liver is not working well.Rifaximin is like a superhero that stays in your belly and fights only bad germs. It stops them from building their families of villains known as harmful germ groups, so they shrink and go away. What’s cool is it doesn’t go into the rest of your body; it stays right where it’s needed most and helps your belly feel better.

Safety Measures and Warning 

Pregnancy

There are no studies supporting that rifaximin causes abnormalities in babies, but there are animal studies on rats and rabbits showing that rifaximin can cause facial, cardiac, eye, and spine-related developmental problems. So, it is not recommended for use during pregnancy.

Breastfeeding

There are no studies supporting that rifaximin passes through breast milk and can cause developmental issues. So, it is recommended to take the medicine only under the doctor’s prescription.

Kidney and Liver Problems

There are studies stating that patients can get mild to severe liver failure if they use this medicine in some individuals, so it is recommended to take the medicine under a doctor’s prescription only.

Rifaximin Interaction with Food Product 

Alcohol and smoking can simultaneously affect the drug’s action and can cause an increase or decrease in the drug’s action.

Rifaximin Interaction with Other Medicines  

Avoid taking Rifaximin 400 mg with the following medicines, as it may increase or decrease the desired effect, or in worse cases, it could be fatal:

Rifaximin Chemical Structure

IUPAC (International Union of Pure and Applied Chemistry)/ Chemical name

(2S,16Z,18E,20S,21S,22R,23R,24R,25S,26R,27S)-5,6,21,23,25-pentahydroxy-2-[4-(2-methylpropyl)imidazo[1,2-a]pyridin-2-yl]-1,3-dioxo-19,27-dimethoxy-13-[4-(methylamino)-3-oxobutyl]-11,28-dioxa-4-azatricyclo[22.3.1.0⁴,⁸]octacosa-16,18,20-trien-26-carboxylic acid

Intake routine/cycle

Daily dose

Take rifaximin exactly as your doctor recommends. The dose may change based on your condition and how well you respond. Do not take more than prescribed without consulting your doctor.

Missed Dose

If you forget to take your medicine, take the medication as soon as you remember. If it’s nearly time for your next dose, skip the missed one and continue with your regular schedule. Always consult the doctor before making any changes to your dosage. 

Overdose

Don’t take more than 2500 mg of rifaximin per day, as it may cause severe overdosing effects like diarrhea, kidney and liver damage, heart problems, and pancreatitis. If you face any of the severe effects, consult the doctor.

Storage

1. Store the medicine at room temperature 
2. Keep away from sunlight and moisture 
3. Keep out of reach of children 

Directions for use 

1. Take Rifaximin exactly as prescribed by your doctor, at the same time each day. 
2. Do not stop taking Rifaximin without your doctor’s approval, even if you feel better. 
3. If you forget to take Rifaximin, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose. 

Rifaximin Summary 

Rifaximin is a special type of antibiotic that works mostly in the intestines It is minimally absorbed into the bloodstream, making it safer for long-term use. Doctors prescribe it to treat traveler’s diarrhea, help people with irritable bowel syndrome diarrhea (IBS-D), and prevent brain-related problems in liver disease (hepatic encephalopathy). Some people may feel tired, experience rapid weight gain, stomach pain and bloating, and trouble breathing while lying down. People with severe liver issues, allergic reactions to similar drugs, or bloody diarrhea should avoid it. Rifaximin doesn’t interact heavily with food, but it can affect how certain medicines work, so always check with your doctor before combining it with others. Exceeding 2500 mg per day of rifaximin may trigger serious overdose effects, including liver and kidney damage, heart issues, and pancreatitis.

FAQ’s

Which class of medicine does rifaximin belong to?

Rifaximin belongs to the non-systemic gastrointestinal antibiotics used to treat travelers diarrhea and inflammatory bowel syndrome associated with diarrhea.

What are the side effects of rifaximin 400 mg tablet?

Some people while using rifaximin may feel tired, experience rapid weight gain, stomach pain and bloating, and have trouble breathing while lying down.

What is the brand name of rifaximin? 

Xifaxan is the most used brand name of the first rifaximin ever manufactured by salix pharmaceuticals USA.

What are the uses of rifaximin? 

Rifaximin is a special type of antibiotic that works mostly in the intestines without entering the bloodstream, making it safer for long-term use. Doctors prescribe it to treat traveler’s diarrhea, help people with irritable bowel syndrome diarrhea (IBS-D), and prevent brain-related problems in liver disease (hepatic encephalopathy) 

Reference 

1. Drugs.com. Rifaximin [Internet]. Drugs.com; 2025 Mar 17 [cited 2025 Jul 14]. Available from. 
2. Robertson KD, Nagalli S. Rifaximin [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 May 22 [cited 2025 Jul 14]. Available from. 
3. National Center for Biotechnology Information. PubChem Compound Summary for CID 6436173, Rifaximin [Internet]. Bethesda (MD): National Library of Medicine (US); [cited 2025 Jul 14]. Available from. 
4. Mayo Clinic. Rifaximin (oral route) [Internet]. Rochester (MN): Mayo Foundation for Medical Education and Research; [cited 2025 Jul 14]. Available from. 
5. WebMD. Xifaxan (rifaximin): Uses, Side Effects, Interactions, Pictures, Warnings, and Dosing [Internet]. WebMD LLC; 2024 Oct 8 [cited 2025 Jul 14]. Available from. 

Siva Krishna Adithya Bhumireddy

Siva Krishna Adithya Bhumireddy completed a Bachelor of Pharmacy from GIET School of Pharmacy, affiliated with Andhra University, and from his 3rd year of graduation, he was working as a freelance medical and publication writer. Having expertise in systematic reviews and clinical research. With his keen interest and skills in research and documentation practices, he also reviewed more than 150 manuscripts from international journals like Elsevier, Springer Nature, and Sage Journals, and all the manuscripts were indexed and appeared in PubMed, Scopus, and Web of Science databases, and he received honorary recognition letters and certificates from all of them. Siva Krishna Adithya also published a few systematic, narrative reviews and a few chapters of international expertise.