Xifaxan (Rifaximin) – Patient Guide (UK)

Xifaxan contains rifaximin, an antibiotic used to treat specific gastrointestinal conditions, particularly those related to abnormal gut bacteria and, in some cases, hepatic encephalopathy. This patient-friendly guide explains what the medicine does, how it works, how it is taken, what to expect, and important safety information.

This information is designed to help you understand your treatment. Always follow the instructions provided with your medicine and discuss any questions with a healthcare professional.

Key product information

How Xifaxan works (mechanism of action)

Rifaximin is a “gut-selective” antibiotic. It works by interfering with how bacteria make essential molecules to survive and multiply.

The antibiotic binds to bacterial DNA-dependent RNA polymerase, blocking RNA production. Without RNA, bacteria cannot grow or replicate effectively.

Because rifaximin is designed to act mainly in the intestine and is not significantly absorbed into the bloodstream, it can help reduce harmful bacterial activity in the gut while limiting whole-body exposure.

Pharmacokinetics: what the body does to rifaximin

“Pharmacokinetics” describes how the body handles a medicine—how it is absorbed, distributed, metabolised, and eliminated.

• Absorption: Rifaximin is poorly absorbed from the gastrointestinal tract. Most of the medicine stays within the gut lumen.
• Systemic exposure: Blood levels are generally low compared with medicines that are absorbed to a greater extent.
• Distribution: Due to low absorption, significant distribution to other tissues is limited.
• Metabolism: Rifaximin undergoes minimal systemic metabolism in many patients because systemic levels are low.
• Elimination: Much of the active fraction is eliminated via the gastrointestinal tract. Only small amounts appear to reach systemic circulation.

In practice, these features contribute to the medicine’s “local gut activity” and may reduce the likelihood of some systemic side effects.

Typical uses in the UK (indications)

Xifaxan is used for certain conditions where abnormal gut bacteria play a role. Indications can vary by country and product licence. In the UK, rifaximin is commonly used for:

• Hepatic encephalopathy (HE): To help reduce recurrence of episodes in adults with liver disease. HE occurs when toxins that are normally cleared by the liver affect brain function.
• Traveller’s diarrhoea and other diarrhoeal illnesses: In some cases, rifaximin may be used for diarrhoea linked to susceptible bacterial causes, particularly when appropriate according to local guidance.

Whether you are prescribed rifaximin depends on your diagnosis, previous treatments, severity, and local clinical recommendations. If you are unsure why you are taking it, check your medicine information or ask a healthcare professional.

How and when to take Xifaxan (timing and dosing)

Always follow the dosing instructions provided with your medicine. Different indications may require different dose schedules. Below are common dosing patterns used in clinical practice.

Typical adult dosing patterns

Important: Specific dosing (strength and number of tablets) may differ depending on the product you receive and the condition being treated. Check the label and the patient information leaflet for your exact regimen.

Timing

• Try to take each dose at consistent times each day.
• If your schedule includes multiple doses per day, space them out evenly (e.g., morning, afternoon, evening).
• If you miss a dose, take it as soon as you remember. If it is close to the next dose, skip the missed dose and continue as normal. Do not take double doses.

Swallowing and preparation

• Take tablets with water. Swallow whole unless your leaflet instructs otherwise.
• If you have difficulty swallowing, speak with a healthcare professional or pharmacist for individual advice.

Food interactions: can you take Xifaxan with meals?

Rifaximin can often be taken with or without food. For many people, this makes it convenient for daily routines. However, real-world comfort and adherence may improve if you take it with food, particularly if you experience mild stomach upset.

• With food: May help if you have a sensitive stomach.
• Without food: Also commonly acceptable depending on your prescribed regimen.
• Consistency matters: Try to take it the same way each day (either always with meals or always between meals) unless your clinician advises changes.

If you have specific concerns (e.g., liver disease requiring special diet), ask a healthcare professional for personalised advice.

Alcohol and medicine interactions

Because rifaximin acts mainly in the gut and has low systemic absorption, the direct interaction between rifaximin and alcohol is not usually described as a major concern. However, alcohol can be unsafe for people with certain underlying conditions—especially liver disease.

Alcohol considerations

• If you have liver disease or hepatic encephalopathy: Alcohol can worsen liver function and raise the risk of encephalopathy. Avoiding alcohol is generally strongly advised.
• If you drink alcohol: Keep it minimal and follow healthcare guidance for your medical condition.

Other medicine interactions

Rifaximin’s low absorption means fewer systemic drug interactions are expected than with antibiotics that reach higher blood levels. Still, interactions can occur, especially when medicines affect gut bacteria or shared pathways.

Tell your pharmacist or healthcare professional about all medicines you take, including:

• Other antibiotics or antimicrobial medicines
• Liver medications
• Medicines that affect stomach acid (your pharmacist can advise whether timing changes are needed)
• Herbal remedies and supplements

If you start a new medicine while taking Xifaxan, check with your pharmacist—particularly if it is intended for the same gut symptoms.

Safety profile: side effects and when to seek help

Like all medicines, Xifaxan (rifaximin) can cause side effects. Many people experience no or mild effects. Below is a patient-friendly overview.

Common side effects

• Nausea
• Constipation or abdominal discomfort
• Abdominal pain or indigestion
• Headache
• Gas or bloating

Less common but important side effects

• Allergic reactions (e.g., rash, itching, swelling)
• Severe diarrhoea or worsening bowel symptoms
• Signs of liver problems (unusual fatigue, yellowing of skin/eyes, dark urine) — seek prompt advice, especially if you have liver disease

Seek urgent medical attention if

• You develop swelling of the face/lips, trouble breathing, or widespread rash
• You experience severe or persistent diarrhoea, especially with fever or blood/mucus
• Your symptoms of hepatic encephalopathy worsen (e.g., confusion, drowsiness, marked changes in behaviour)

If you notice any side effects, you can report them via the UK Yellow Card Scheme or speak with a healthcare professional.

Antibiotic-related concerns

Antibiotics can occasionally disrupt the normal balance of gut bacteria. Very rarely, this can lead to overgrowth of other organisms and inflammation of the colon. Contact a healthcare professional promptly if you develop severe diarrhoea during or after treatment.

Practical use tips to get the best results

• Complete the course as advised. Stopping early may reduce effectiveness.
• Stay consistent with dosing times.
• Hydrate if you are taking it for diarrhoea. Use oral rehydration solutions if needed.
• Track symptoms: note improvement, and seek medical advice if symptoms worsen or do not improve within the expected time.
• Consider your liver condition (if relevant): take precautions with alcohol and avoid missed meals if advised.
• Probiotics? If you are considering probiotics during antibiotic treatment, discuss this with a pharmacist, especially if you have significant liver disease or immune problems.

Missed dose and what to do

If you miss a dose, take it when you remember unless it is almost time for the next dose. If close to the next dose, skip the missed dose and continue your schedule. Do not take extra tablets to “catch up.”

Alternative treatment options

The best alternative depends on the underlying condition being treated. Below are commonly considered options—your clinician will choose based on diagnosis, local recommendations, allergies, and medical history.

For hepatic encephalopathy

• Lactulose (commonly used to manage and prevent episodes)
• Other gut-targeted approaches as indicated by your specialist team

For diarrhoeal illnesses

• Oral rehydration and supportive care
• When appropriate and guided by cause/severity: other antibiotics may be considered
• Avoid unnecessary antibiotics for non-bacterial causes, as they may not help

If you are asking about alternatives due to side effects or supply issues, a pharmacist can help review options based on your specific situation.

Recent UK guidance and clinical context

Treatment approaches in the UK continue to evolve as evidence develops. For bacterial diarrhoea, management typically emphasises: correct diagnosis (when to test), supportive care (especially rehydration), and targeted antibiotics only when benefits outweigh risks.

For hepatic encephalopathy, international and local guidance often prioritises strategies that reduce gut-derived toxins and prevent recurrence. In many practice settings, rifaximin is used alongside standard care (such as lactulose) in patients who are at risk of recurrent episodes.

Your healthcare team may also consider local antimicrobial stewardship recommendations to help reduce the risk of resistance and inappropriate antibiotic use.

Market and legal context for the UK

In the UK, medicines must be authorised and marketed in line with medicines regulation. Xifaxan (rifaximin) is available through appropriate healthcare channels in accordance with its licensed indications and prescribing information.

Online pharmacies should follow UK legal and regulatory requirements for sale, supply, and provision of patient information. Availability may differ across batches and suppliers.

Delivery and availability (UK online pharmacy)

Delivery options depend on the pharmacy and the product’s availability. Commonly:

• Stock availability: Xifaxan may be held in stock or sourced from wholesalers depending on demand and strength.
• Dispatch times: Orders are often dispatched within 24–72 hours (excluding weekends and public holidays) when in stock.
• Delivery service: Royal Mail or courier services may be used, depending on the pharmacy’s arrangements.
• Cold chain: Xifaxan tablets typically do not require refrigeration.

If you need the medicine urgently (e.g., for symptoms that are worsening), check availability with customer support or contact a pharmacist.

How to store Xifaxan

• Keep tablets in their original packaging.
• Store at room temperature unless your leaflet instructs otherwise.
• Keep out of sight and reach of children.
• Do not use after the expiry date shown on the pack.

FAQ: common questions about Xifaxan (rifaximin)

1) What is Xifaxan used for?

Xifaxan (rifaximin) is an antibiotic used for specific gastrointestinal conditions. In the UK, it is commonly used for hepatic encephalopathy (to help reduce recurrence) and may also be used for selected diarrhoeal infections based on cause and clinical judgement.

2) How quickly will I feel better?

Some people notice symptom improvement within a few days, but the timeline depends on the condition being treated and the severity. If your symptoms do not improve or worsen, contact a healthcare professional.

3) Can I take Xifaxan with food?

Often, rifaximin can be taken with or without food. If you find it more comfortable with meals, you can usually take it that way—just keep the routine consistent.

4) Is Xifaxan the same as other antibiotics?

It belongs to the antibiotic family, but rifaximin is notable for being poorly absorbed and primarily acting in the gut. It may behave differently from antibiotics that are absorbed more extensively into the bloodstream.

5) Can I drink alcohol while taking it?

There is not typically a major direct interaction between rifaximin and alcohol, but alcohol can be unsafe—especially if you have liver disease or hepatic encephalopathy. For those situations, alcohol avoidance is generally recommended.

6) Are there drug interactions I should watch for?

Rifaximin has relatively low systemic exposure, so fewer interactions are expected compared with some other antibiotics. Still, interactions are possible. Tell your pharmacist about all medicines and supplements you take, including stomach acid medicines and other antibiotics.

7) What if I miss a dose?

Take it when you remember unless it is close to the next dose. If so, skip the missed dose and continue as normal. Do not take double doses.

8) What side effects are most common?

Common side effects may include nausea, abdominal discomfort, constipation, headache, and gas. Most are mild. Seek advice urgently for allergy symptoms or severe/persistent diarrhoea.

9) Should I stop Xifaxan if my diarrhoea improves?

Unless your healthcare professional tells you to stop, complete the prescribed course. Stopping early may reduce effectiveness.

10) When should I contact a clinician urgently?

Contact urgent medical care if you have signs of an allergic reaction, severe diarrhoea (especially with blood or fever), breathing problems, swelling of the face/lips, or worsening symptoms related to hepatic encephalopathy.

Summary

Xifaxan (rifaximin) is a gut-targeted antibiotic used for selected gastrointestinal conditions, including hepatic encephalopathy (to help reduce recurrence) and certain diarrhoeal illnesses. It works by inhibiting bacterial RNA production and is characterised by poor absorption, meaning it mostly acts within the intestine. When taken as directed and with appropriate supportive care, it can help manage symptoms and reduce recurrence in suitable patients.