Rifaximin (Xifaxanta)

What is Rifaximin?

Rifaximin (sold under the brand name Xifaxanta in the European Union) is a semi-synthetic, broad-spectrum antibiotic derived from Rifamycin SV. It is distinguished from conventional antibiotics by one critical pharmacological property: it is almost entirely non-absorbed. Less than 0.4% of an oral dose reaches the systemic circulation, meaning that Rifaximin acts almost exclusively within the gastrointestinal tract.

This unique property makes Rifaximin clinically valuable for intestinal conditions where gut-focused antibacterial activity is desirable without systemic antibiotic exposure. The European Medicines Agency (EMA) has approved Rifaximin for:

• Irritable Bowel Syndrome with Diarrhoea (IBS-D) in adults (as Xifaxanta 550 mg)
• Reduction of risk of overt hepatic encephalopathy recurrence in adults
• Traveller’s diarrhoea caused by non-invasive strains of Escherichia coli

How does Rifaximin work?

Rifaximin inhibits bacterial DNA-dependent RNA polymerase, the enzyme responsible for transcribing bacterial DNA into RNA. By blocking this enzyme, Rifaximin prevents bacteria from synthesising the proteins they need to replicate and survive.

Because Rifaximin acts within the intestinal lumen rather than systemically, it selectively modifies the composition of the gut microbiome — the trillions of microorganisms that inhabit the intestinal tract. In IBS-D:

• Dysbiosis correction: Clinical evidence supports a role for gut bacterial dysbiosis and small intestinal bacterial overgrowth (SIBO) in a subset of IBS-D patients. By reducing populations of pathogenic or overgrown bacteria, Rifaximin may restore a healthier microbial balance.
• Reduced intestinal inflammation: Rifaximin appears to have anti-inflammatory properties mediated partly through pregnane X receptor (PXR) activation, independent of its direct antibacterial effects.
• Reduced gut permeability: Evidence suggests Rifaximin may help restore intestinal barrier integrity, reducing the “leaky gut” phenomenon associated with some forms of IBS.
• Symptom relief: Clinical trials in IBS-D have demonstrated statistically significant improvement in bloating, global IBS symptoms, and stool consistency compared to placebo.

Who is Rifaximin for?

Rifaximin is appropriate for adults with:

• IBS-D: Confirmed or clinically suspected irritable bowel syndrome with diarrhoea as the predominant symptom pattern, who have not achieved adequate relief with dietary measures, antispasmodics, or other first-line treatments
• Traveller’s diarrhoea: Uncomplicated diarrhoea acquired during travel to endemic regions, caused by non-invasive E. coli (Rifaximin is not appropriate for invasive pathogens causing dysentery or bloody diarrhoea)
• Hepatic encephalopathy: To reduce recurrence risk in patients with cirrhosis and a history of overt hepatic encephalopathy (typically under specialist supervision)

Rifaximin is not appropriate for:

• Diarrhoea complicated by fever or blood in the stool (invasive pathogens — requires systemic antibiotics)
• Children under 12 years (IBS-D indication)
• Patients with severe intestinal obstruction
• Patients with hypersensitivity to Rifaximin or other Rifamycin antibiotics
• Pregnant women (insufficient safety data)

Dosage

For adults, EMA-approved dosing schedules are:

Indication	Dose	Duration
IBS-D	550 mg three times daily	14 days
Traveller’s diarrhoea	200 mg three times daily	3 days
Hepatic encephalopathy prevention	550 mg twice daily	Long-term (specialist supervision)

Tablets may be taken with or without food. For IBS-D, the 14-day course can be repeated if symptoms recur, under medical guidance.

Side effects

Rifaximin is generally well tolerated, in large part because of its minimal systemic absorption.

Common side effects

• Nausea: Mild and generally transient
• Flatulence (gas): Increased gas production, which may be related to shifts in gut bacterial populations
• Abdominal pain: May overlap with underlying IBS symptoms
• Headache
• Dizziness (uncommon)

Less common side effects

• Rectal tenesmus (sensation of incomplete emptying)
• Peripheral oedema (fluid retention — reported in hepatic encephalopathy patients at long-term doses)
• Skin rash

Serious but rare side effects

• Clostridium difficile-associated diarrhoea (CDAD): As with all antibiotics, Rifaximin carries a theoretical risk of C. difficile overgrowth, though the risk is substantially lower than with systemically absorbed antibiotics due to its local intestinal action.
• Severe allergic reactions: Including anaphylaxis and serious skin reactions. Patients with known Rifamycin hypersensitivity are at higher risk (cross-reactivity possible).

Rifaximin vs alternatives for IBS-D

Medicine	Class	Mode of Action	Best For
Rifaximin (Xifaxanta)	Non-absorbed antibiotic	Gut microbiome modification	IBS-D, bloating, SIBO
Loperamide	Opioid receptor agonist	Slows intestinal motility	Acute diarrhoea management
Hyoscine Butylbromide	Antispasmodic	Smooth muscle relaxation	IBS cramping and pain
Low-FODMAP diet	Dietary intervention	Reduces fermentable substrate	First-line IBS management
Eluxadoline	Mixed opioid agonist/antagonist	Reduces bowel motility + pain	IBS-D (restricted use, specialist)

How to get Rifaximin online in Europe

Rifaximin is a prescription-only medicine in the EU. Prescrivia operates as a technology intermediary — we do not prescribe medicines, employ doctors, or sell medicines. Our platform connects patients with independent EU-registered doctors who can conduct online digestive health assessments.

The process:

1. Complete a digestive health assessment: Describe your IBS symptoms, predominant pattern (diarrhoea, constipation, mixed), symptom severity, and previous treatments.
2. Doctor review: An independent EU-registered doctor reviews your assessment. If Rifaximin is clinically appropriate for IBS-D or another qualifying indication, they may issue a prescription.
3. Prescription and fulfilment: If a prescription is issued, it is forwarded to a licensed EU pharmacy partner for dispensing and delivery.

Important: Prescrivia does not guarantee that a prescription will be issued. All prescribing decisions are made independently by qualified medical professionals based on your individual clinical circumstances.

Important safety information

Do not take Rifaximin if you:

• Have diarrhoea accompanied by fever or blood in the stool (seek urgent medical attention — systemic infection is likely)
• Are hypersensitive to Rifaximin or other Rifamycin antibiotics
• Are pregnant or breastfeeding
• Have significant intestinal obstruction

Tell your doctor if you:

• Are taking Ciclosporin (a significant drug interaction — Rifaximin exposure increases substantially)
• Are taking P-glycoprotein inhibitors (may increase systemic Rifaximin exposure)
• Have severe hepatic impairment (Rifaximin accumulation possible in hepatic encephalopathy patients with severe liver disease)
• Experience worsening diarrhoea or new symptoms during treatment

Stop treatment and seek medical advice if:

• Diarrhoea continues for more than 48 hours without improvement, or worsens
• You develop fever or see blood in your stool

Sources

Medical information on this page is based on the following sources:

• European Medicines Agency (EMA). Xifaxanta (Rifaximin) — Summary of Product Characteristics and European Public Assessment Report. ema.europa.eu
• Pimentel M, et al. Rifaximin therapy for patients with irritable bowel syndrome without constipation (TARGET 1 and TARGET 2). N Engl J Med. 2011;364:22-32.
• World Health Organization (WHO). Diarrhoeal diseases. who.int
• Cremonini F, Lembo A. Rifaximin for the treatment of irritable bowel syndrome. Expert Opin Pharmacother. 2012.

This content is provided for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for advice relevant to your individual health circumstances.