Rifaximin

Basic rifaximin information

• INN (international nonproprietary name): Rifaximin
• Brand names available in the United Kingdom: Targaxan (550 mg tablets), Xifaxanta (200 mg tablets)
• ATC code: A07AA11
• Forms and dosages: film-coated tablets 200 mg and 550 mg
• Manufacturers in the United Kingdom: Norgine
• Registration status in the United Kingdom: Licensed by the MHRA; prescription-only medicine
• OTC / Rx classification: Prescription-only medicine (POM)

Counselling points for patients

What should a patient know before starting rifaximin?

• Complete the course: Take the full prescribed course even if symptoms improve early.
• Monitor stools: Note changes in stool frequency, consistency and the presence of blood.
• Report severe symptoms: Seek urgent review for severe abdominal pain, persistent or bloody diarrhoea, or signs of dehydration.
• Antibiotic resistance: Discuss concerns about resistance and the specific, gut‑limited action of rifaximin.
• Storage: Keep tablets in the original pack away from moisture and children.
• Follow‑up: Arrange review for repeat prescriptions or if symptoms recur.

Licensed indications and MHRA status

Which uses are commonly licensed in the UK?

Rifaximin is authorised in the UK for specific indications depending on brand and formulation, commonly for traveller’s diarrhoea and for hepatic encephalopathy maintenance therapy.

The Summary of Product Characteristics (SmPC) for each product gives the exact authorised uses.

Strengths and pack options

Which strengths and pack options are available?

Common tablet strengths for rifaximin include 200mg and 550mg.

Pack sizes commonly reflect the indication: a three‑day 200mg three times daily pack for traveller’s diarrhoea, a 14‑day 550mg three times daily pack for IBS‑D where licensed, and larger supplies for maintenance in hepatic encephalopathy, such as 550mg tablets for twice‑daily use.

How rifaximin works (practical summary)

What is the mechanism of action in plain terms?

Rifaximin is a rifamycin derivative that binds to bacterial RNA polymerase to inhibit transcription.

It is poorly absorbed from the gut, so most of its activity is localised to the intestinal lumen.

This gut‑limited action makes it useful for treating infections and conditions where modulation of the gut flora is desired.

Pharmacokinetics important for counselling

Which pharmacokinetic points matter for patients?

Very low systemic bioavailability reduces the risk of systemic adverse reactions and lowers the likelihood of systemic drug‑drug interactions.

The therapeutic effect is concentrated in the intestinal tract rather than the bloodstream.

Minimal absorption is an intentional and beneficial property for gut‑targeted therapy.

What patients can reasonably expect

How quickly should symptoms improve and what are realistic outcomes?

For traveller’s diarrhoea most adults will notice a rapid reduction in stool frequency during a three‑day course, particularly when the causative agent is non‑invasive Escherichia coli.

In IBS‑D some patients report symptomatic improvement in abdominal pain and stool consistency after a 14‑day course, though benefits may be temporary for some people.

For hepatic encephalopathy maintenance when used alongside lactulose, rifaximin reduces the recurrence of overt HE in many patients and may reduce hospital admissions.

Common dosing patterns (summary — always follow SmPC)

What are the typical adult dosing patterns used in practice?

Traveller’s diarrhoea is commonly treated with 200mg three times daily for three days, depending on the brand.

IBS‑D regimens where used are often 550mg three times daily for 14 days.

Hepatic encephalopathy maintenance often uses 550mg twice daily alongside lactulose.

Patients should follow the prescribing clinician’s instructions and the SmPC for the specific product supplied.

Administration tips for patients

Practical steps to make dosing simpler and safer.

1. Start: Take the first dose as directed by the prescriber and note the dosing schedule.
2. During treatment: Use phone reminders for multi‑day courses to aid adherence.
3. Missed dose: If a dose is missed, take it as soon as remembered unless it is near the next scheduled dose; do not double up.
4. Finish course: Complete the full course unless advised otherwise by a clinician.

Absolute contraindications

When should rifaximin not be used?

Do not use rifaximin in patients with a known hypersensitivity to rifaximin or to other rifamycins.

Check product excipients as some formulations may contain lactose or other agents that cause hypersensitivity for certain patients.

Cautions and special groups

Which patient groups need extra consideration?

Pregnancy and breastfeeding data are limited; use only when the potential benefit justifies any risk and seek specialist advice for pregnant or breastfeeding patients.

Paediatric guidance varies; some products include paediatric dosing for traveller’s diarrhoea — consult the SmPC for brand‑specific advice.

Severe hepatic impairment requires specialist input when using rifaximin for hepatic encephalopathy maintenance and monitoring should be arranged.

Common and important adverse drug reactions

What side effects should patients expect and watch for?

Common adverse effects include nausea, abdominal pain, flatulence and headache.

Serious but rare harms include severe allergic reactions and Clostridioides difficile‑associated diarrhoea because antibiotics can alter gut flora.

Advise patients to report persistent diarrhoea, blood in stools or severe abdominal pain promptly.

Monitoring and reporting

What monitoring is necessary and how should patients report problems?

Short courses generally do not require routine blood monitoring due to minimal systemic absorption.

For long‑term use in hepatic encephalopathy coordinate monitoring with the specialist team and review hepatic function and clinical response regularly.

Encourage patients to report suspected adverse reactions via the MHRA Yellow Card scheme.

Symptoms that require urgent review include severe abdominal pain, persistent high fever, blood in stool and signs of systemic allergic reaction.

Interaction profile (practical overview)

Are drug interactions a major concern with rifaximin?

Because rifaximin has negligible systemic absorption, systemic drug–drug interactions are uncommon.

However, the rifamycin class is known for CYP enzyme induction in systemic rifamycins, so clinicians should use caution and consider potential interactions with narrow‑therapeutic‑index drugs.

Interactions and medicines needing extra care

Which medicines and situations need extra care?

• Anticoagulants → Check INR monitoring and advise the patient to inform their GP if they are on warfarin.
• Immunosuppressants → Review ciclosporin and similar agents with the prescriber.
• Recent Antibiotics → Flag patients who have recently taken broad‑spectrum antibiotics for C. difficile risk.
• Concomitant Medicines → Ensure prescriber has reviewed the full medication list.

Availability in the UK

Rifaximin is a prescription-only medicine (POM) in the UK.

In our online pharmacy, rifaximin is available without a prescription, with discreet delivery to the United Kingdom in 5‑14 days.

Storage and handling for patients

How should patients keep rifaximin at home?

Store rifaximin at room temperature away from moisture and direct sunlight.

Keep the medicine in its original packaging together with the leaflet.

No refrigeration is required and tablets should be kept out of reach of children.

Therapeutic alternatives and add‑ons

What are possible alternatives by indication?

For traveller’s diarrhoea alternatives include ciprofloxacin or azithromycin depending on local resistance patterns and clinical judgement.

For C. difficile infection management metronidazole and vancomycin are specialist‑directed alternatives and require appropriate clinical oversight.

In hepatic encephalopathy rifaximin is often used in combination with lactulose as an adjunct to reduce recurrence.

Adjunctive measures across indications can include oral rehydration salts, probiotics and short‑term antidiarrhoeal agents where appropriate.

Delivery across the United Kingdom