Rifaximin

Generic name: rifaximin
Brand name: Xifaxan
Dosage form: oral tablet (200 mg; 550 mg)
Drug class: Miscellaneous antibiotics

Medically reviewed by A Ras MD.

What is rifaximin used for?

Rifaximin is used to treat diarrhea. It is used to prevent brain problems caused by very bad liver disease. Rifaximin is also used to treat irritable bowel syndrome. Rifaximin may be given to you for other reasons.

Description

XIFAXAN tablets contain rifaximin, a non-aminoglycoside semi-synthetic, nonsystemic antibiotic derived from rifamycin SV. Rifaximin is a structural analog of rifampin. The chemical name for rifaximin is (2S,16Z,18E,20S,21S,22R,23R,24R,25S,26S,27S,28E)-5,6,21,23,25-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-á]-benzimidazole-1,15(2H)-dione,25-acetate. The empirical formula is C43H51N3O11 and its molecular weight is 785.9. The chemical structure is represented below:

XIFAXAN tablets for oral administration are film-coated and contain 200 mg or 550 mg of rifaximin.

Inactive ingredients:

Each 200 mg tablet contains colloidal silicon dioxide, disodium edetate, glycerol palmitostearate, hypromellose, microcrystalline cellulose, propylene glycol, red iron oxide, sodium starch glycolate, talc, and titanium dioxide.

Each 550 mg tablet contains colloidal silicon dioxide, glycerol palmitostearate, microcrystalline cellulose, polyethylene glycol/macrogol, polyvinyl alcohol, red iron oxide, sodium starch glycolate, talc, and titanium dioxide.

Before taking rifaximin, tell your doctor:

If you are allergic to rifaximin; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
If you have diarrhea along with fever or blood in the stool.

This is not a list of all drugs or health problems that interact with rifaximin.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take rifaximin with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take rifaximin?

Tell all of your health care providers that you take rifaximin. This includes your doctors, nurses, pharmacists, and dentists.
Do not use longer than you have been told. A second infection may happen.
If you are taking rifaximin for travelers’ diarrhea, call your doctor right away if diarrhea lasts more than 24 to 48 hours or gets worse.
Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using rifaximin while you are pregnant.
Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

How is rifaximin best taken?

Use rifaximin as ordered by your doctor. Read all information given to you. Follow all instructions closely.

Keep taking rifaximin as you have been told by your doctor or other health care provider, even if you feel well.
Take with or without food.

What do I do if I miss a dose?

Take a missed dose as soon as you think about it.
If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
Do not take 2 doses at the same time or extra doses.

What are the side effects of rifaximin that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
Swelling in the arms or legs.
Swelling of belly.
Feeling very tired or weak.
Shortness of breath.
Low mood (depression).
Fever.
Diarrhea is common with antibiotics. Rarely, a severe form called C diff–associated diarrhea (CDAD) may happen. Sometimes, this has led to a deadly bowel problem (colitis). CDAD may happen during or a few months after taking antibiotics. Call your doctor right away if you have stomach pain, cramps, or very loose, watery, or bloody stools. Check with your doctor before treating diarrhea.

What are some other side effects of rifaximin?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

Headache.
Dizziness.
Belly pain.
Upset stomach.
Feeling tired or weak.
Muscle spasm.
Nose or throat irritation.
Joint pain.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out rifaximin?

Store at room temperature.
Store in a dry place. Do not store in a bathroom.
Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.