Rifaximin (Xifaxan) - Uses, Dose, MOA, Side effects, Brands

Rifaximin binds to bacterial DNA-dependent RNA polymerase resulting in the inhibition of bacterial RNA synthesis. It is a gut-antiseptic that clears the intestines of bacterial overgrowth especially in patients with liver disease, malabsorption, IBS, and diabetes.

Rifaximin (Xifaxan) Uses (Indications):

  • Hepatic encephalopathy:

    • It is used in the reduction in the risk of overt hepatic encephalopathy recurrence in adults
  • Irritable bowel syndrome with diarrhea:

    • It is used to treat persons with IBS-D (irritable bowel syndrome with diarrhoea).
  • Traveler's diarrhea:

    • It is used to treat travellers' diarrhoea in adults and children under the age of 12 that is brought on by non-invasive strains of E. coli.
    •  Rifaximin should not be used in patients having diarrhea complicated by fever or blood in the stool or diarrhea caused by pathogens other than E. coli.
  • Off Label Usage of Rifaximin in Adults:

    • Recurrence of Clostridioides difficile infection.
    • Treatment of Overt hepatic encephalopathy episodes

Read: Linaclotide (Linzess) for IBS

Rifaximin (Xifaxan) Dose in Adults

Off label Dosage in the treatment of Clostridioides (formerly Clostridium) difficile infection (second or subsequent recurrence):

  • For 20 days, 400 mg orally, three times per day.
  • Give after a standard course of oral vancomycin

Rifaximin (Xifaxan) Dose in the treatment of Hepatic encephalopathy:

  • Reduction of overt hepatic encephalopathy recurrence:
    • 550 mg 2 times daily is given.

Rifaximin (Xifaxan) Off label dosage in the treatment of hepatic encephalopathy:

  • 400 mg is given every 8 hours for 5 to 10 days

Rifaximin (Xifaxan) Dose in the treatment of Irritable bowel syndrome with diarrhea (IBS-D):

  • Orally 550 mg 3 times daily is given for 14 days
  • It may be retreated up to 2 times with the same dosing regimen if symptoms recur.

Rifaximin (Xifaxan) Dose in the treatment of Traveler's diarrhea:

  • Orally 200 mg 3 times is given daily for 3 days

Rifaximin (Xifaxan) Dose in Children:

Rifaximin (Xifaxan) Dose in the treatment of Travelers' Diarrhea:

  • Consider alternative medication if symptoms persist or worsen after 24 to 48 hours of treatment.
  • Children 3 to 11 years:

    • 100 mg 4 times daily is given for up to 5 days has been used in 38 children (age range: 3 to 8 years) to treat infectious diarrhea
  • Children ≥12 years and Adolescents:

    • 200 mg 3 times is given daily for 3 days

Rifaximin dose in the treatment of Hepatic encephalopathy:

  • Adolescents ≥18 years:
    • For reduction of overt hepatic encephalopathy recurrence, the dose is  550 mg 2 times daily

Rifaximin (Xifaxan) Dosage in the treatment of Inflammatory bowel disease (IBD) (Crohn disease and ulcerative colitis):

  • Children ≥8 years and Adolescents:
    • Divided doses of 10 to 30 mg/kg/day are administered.
    • The daily dose cap is 1200 mg.

Rifaximin (Xifaxan) Dose in the treatment of small intestinal bacterial overgrowth (SIBO) (eg, irritable bowel syndrome [IBS] and chronic abdominal pain):

  • Children ≥3 years and Adolescents:
    • 200 mg 3 times daily is given,

Pregnancy Risk Factor: C

  • Studies on animal reproduction have revealed negative outcomes.
  • Due to rifaximin's minimal oral absorption in people with normal liver function, the exposure of the foetus to the drug is most likely minor.

Rifaximin use during breastfeeding:

  • If the drug is present in human milk is unknown.
  • According to the manufacturer breast-feeding during therapy is a decision that should be made after considering the risks to the infant as well as the benefits to the mother.
  • Due to the low oral absorption of rifaximin by patients with normal hepatic function it is unlikely that the infant will be exposed to it.

Rifaximin dose in Kidney disease:

  • The manufacturer's labelling does not mention dosage modifications (has not been studied).

Rifaximin dose in Liver disease:

  • No dosage adjustment required.
  • Use cautiously in severe impairment (Child-Pugh class C).
  • However, systemic absorption is limited and pharmacokinetic parameters are highly variable.

  • The frequency of side effects is generally higher after the treatment for hepatic encephalopathy (HE).

Common Side Effects of Rifaximin:

  • Cardiovascular:

    • Peripheral Edema
  • Central Nervous System:

    • Dizziness
    • Fatigue
  • Hepatic:

    • Ascites
  • Gastrointestinal:

    • Nausea

Less Common Side Effects of Rifaximin (Xifaxan):

  • Central Nervous System:

    • Headache
    • Depression
  • Dermatological:

    • Pruritus
    • Skin Rash
  • Gastrointestinal:

    • Abdominal Pain
    • Pseudomembranous Colitis
  • Hematologic & Oncologic:

    • Anemia
  • Hepatic:

    • Increased Serum ALT
  • Neuromuscular & Skeletal:

    • Muscle Spasm
    • Arthralgia
    • Increased Creatine Phosphokinase
  • Respiratory:

    • Nasopharyngitis
    • Dyspnea
    • Epistaxis
  • Miscellaneous:

    • Fever

Contraindications to Rifaximin (Xifaxan):

  • Hypersensitivity to rifaximin or other rifamycin anti-biotics or any part thereof

Warnings and precautions

  • Hypersensitivity

    • Exfoliative dermatitis, angioneurotic swelling, pruritus and urticaria have all been reported.
    • As little as 15 minutes after drug administration, allergic reactions can occur.
  • Superinfection

    • Long-term use can lead to fungal and bacterial superinfections, such as C. difficile-associated diarrhea(CDAD) or pseudomembranous collitis.
    • CDAD was seen after more than two months of post-antibiotic treatment.
  • Diarrhea:

    • Avoid use in the treatment or prevention of diarrhea with fever and/or bloody stool.
    • If symptoms persist or worsen, consider alternate treatment.
  • Hepatic impairment

    • Patients with End-Stage Liver Diseases (MELD) scores >25 have not shown any evidence of efficacy in preventing encephalopathy.
    • Use caution in patients with severe liver impairment (Child-Pugh Class C).

Rifaximin: Drug Interaction

Risk Factor C (Monitor therapy)

BCG Vaccine (Immunization)

Antibiotics may reduce the BCG vaccine's therapeutic effect (Immunization).

CycloSPORINE (Systemic)

RifAXIMin serum levels can rise.

Lactobacillus and Estriol

The therapeutic effects of Lactobacillus and Estriol may be reduced by antibiotics.

P-glycoprotein/ABCB1 Inhibitors

RifAXIMin serum levels can rise.

Risk Factor D (Consider therapy modification)

Sodium Picosulfate

Antibiotics may reduce Sodium Picosulfate's therapeutic impact. Management: If a patient previously used or is currently using an antibiotic, think about utilising an alternative product for bowel cleansing prior to a colonoscopy.

Risk Factor X (Avoid combination)

BCG (Intravesical)

Antibiotics may lessen BCG's therapeutic effects (Intravesical).


  • Hypersensitivity reactions
  • temperature
  • blood in stool
  • change in symptoms
  • monitor changes in mental status in hepatic encephalopathy

How to administer Rifaximin (Xifaxan)?

  • Administer orally with or without food.

Mechanism of action of Rifaximin (Xifaxan):

  • Rifaximin usually inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase.

Absorption: Oral: Traveler's diarrhea: Low Hepatic encephalopathy: Increased absorption in Child-Pugh class C patients compared with patients with Child-Pugh class A

Protein binding:

  • In Healthy subjects: 67.5%
  • In patients with Hepatic impairment: 62%


  • Extensive, mainly by CYP3A

Half-life elimination:

  • Healthy subjects: 5.6 hours
  • IBS-D patients: 6 hours

Time to peak:

  • In Healthy subjects and ISB-D patients: ~1 hour


  • Via Feces (96.6%; primarily as unchanged drug) & urine (0.32%)

International Brands of Rifaximin:

  • Xifaxan
  • Zaxine
  • Alfa Normix
  • Arfla
  • Aximin
  • Bang Yi
  • Colidimin
  • Coloximina
  • Fatroxim
  • Faxinorm
  • Flonorm
  • Henlix
  • Idibact
  • Ifaxim
  • Lormyx
  • Normix
  • Qian Er Fen
  • Refero
  • Rifadom
  • Rifatime
  • Rifax
  • Rifaxin
  • Rifxima
  • Spiraxin
  • Targaxan
  • Tixtar
  • Tixteller
  • Tixtetller
  • Trencedia
  • Xifamin
  • Xifaxan
  • Xifaxanta

Rifaximin Brand Names in Pakistan:

Rifaximin 200 mg Tablets

Hidrofax S.J. & G. Fazul Ellahie (Pvt) Ltd.
Nimixa Getz Pharma Pakistan (Pvt) Ltd.
Nixaf Sami Pharmaceuticals (Pvt) Ltd.
Rifaxa Ferozsons Laboratoies Ltd.


Rifaximin 550 mg Tablets

Nimixa Getz Pharma Pakistan (Pvt) Ltd.
Nixaf Sami Pharmaceuticals (Pvt) Ltd.
Xifaxa Brookes Pharmaceutical Laboratories (Pak.) Ltd.