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Rifaximin (Xifaxan)

Rifaximin is a form of antibiotic designed to kill the bacteria that cause illness and pain. The active ingredient in this substance, rifaximin, acts within the intestine and usually is not absorbed into the bloodstream, reducing the risk of side effects.

What is rifaximin?

Rifaximin is an antibiotic that works within a specific targeted area. It helps to kill bacteria in the intestine known as Escherichia coli (E. coli), which can often be the cause of traveller’s diarrhoea – a condition that happens when an individual is exposed to substances or foods that their stomach and digestive system is not used to. When you eat new food or drink water from a country that you are not used to, you are more likely to have uncomfortable bowel movements.

This medication is only available when given by prescription, and it should not be taken by people who have other issues aside from diarrhoea, such as severe stomach pains, bloody stool movements or a persistent fever. Rifaximin works by reducing the growth of bacteria, causing it to die out. This medicine is only available in tablet form. Some forms of E. coli can be deadly and therefore it is important that you get a check-up with your doctor as soon as possible, to check your blood pressure and levels of hydration.

When is rifaximin used?

Rifaximin is most commonly given for the treatment of traveller’s diarrhoea, but it can also be effective at preventing and treating other forms of illness. In some cases, it is used to prevent the onset of a condition called hepatic encephalopathy in people who have poorly functioning livers. The condition can cause the brain to work poorly, and rifaximin may help you to think more clearly.

Rifaximin works by killing bacteria specifically within the intestine and preventing further growth. Crucially, this medicine will only treat bacterial infections and will not treat any form of viral infection such as the flu. Using any kind of antibiotic for reasons beyond their intended use can cause future problems, such as resistance to that medication.

How do you use rifaximin?

When using any new medication, it is always important to read the instructions provided in your patient leaflet. The information leaflet included with your medication will provide you with useful information on how to take the tablet, and which other medications you should avoid when you are using this substance.

Follow the instructions given to you during your consultation carefully, and make sure that you do not take more or less of the medication than was prescribed to you. If you have any questions, contact your consultant or a local pharmacist. The way that you manage your treatment will depend on a number of factors, including what you are taking rifaximin tablets for. To take this antibiotic effectively, you will need to swallow the rifaximin tablet whole with a glass of water. Do not crush the tablet. For the best outcomes, try to take the rifaximin tablet at the same times throughout the day. To help you remember, you may want to set an alarm and take your medication at a specific time each day.

What dosages are there?

The dosage for rifaximin tablets will depend on your medical condition, as well as how you might have responded for similar antibiotic treatments in the past. If you are using rifaximin for traveller’s diarrhoea, then your doctor will usually recommend taking one tablet three times a day. You will be able to take rifaximin with or without food.

You should not use rifaximin for traveller’s’ diarrhoea for more than three days. If you have been given rifaximin tablets for hepatic encephalopathy, you will need to take them by mouth twice a day. Take just one tablet with each dose, and make sure that you use the medication at evenly spaced times. You will be told how long you should continue to take this medication, and you should continue to take the rifaximin tablets for as long as recommend. Do not stop taking them before you have run out of the prescribed amount, even if your symptoms seem to have disappeared.

If you forget to take a rifaximin tablet, take it as soon as you remember but do not double up on pills to make up for the one that you have missed. Tell your doctor if you are still having issues with diarrhoea after two days of using this medication, as you may need a different treatment. Tell your doctor immediately if you have a fever alongside your diarrhoea when taking rifaximin tablets.

What are the side effects of rifaximin?

Rifaximin is a unique form of antibiotic because it is designed to work on a very specific area of the body. Because this medication works actively within the intestines, it is not usually absorbed into the blood stream. The less of a medication that you get into your blood stream, the lower your chances of side effects become.

However, just because the risk of side effects with this substance are low, does not mean that some people will not react poorly to rifaximin. In some cases, you may find that you have some common side effects when you first begin using the medication, as your body will not be used to the new substances yet. These common side effects can include gastrointestinal symptoms such as feelings of sickness or a general stomach-ache. Some people also suffer from drowsiness, fatigue and headaches.

In certain rare conditions, rifaximin tablets may cause a severe issue with the intestines known as clostridium difficile diarrhoea, which occurs due to a specific kind of resistant bacteria in the body. The problem may happen either during your treatment, or months after you have stopped using the medication. Tell your doctor if you ever develop blood or mucus in your stool, persistent diarrhoea or pain and cramping in your stomach. Avoid using opioid or anti-diarrhoea medications if you have any of the side effects above, as they can make your condition worse.

While it is rare to have a severe allergic reaction to this medication, you should always be aware of the symptoms. Seek medical attention immediately if you notice a rash or itching anywhere on your body, discomfort caused by swelling in the throat, tongue or face, or severe dizziness. Seek help straight away if you have trouble breathing after taking rifaximin tablets.

When should you not use rifaximin?

Some people will be more likely to have side effects when taking rifaximin tablets because of their medical background or condition. It is important to answer all of the questions asked by your consultant and fill out your forms truthfully to ensure that you are getting a safe treatment for your needs. Tell your consultant about your medical history, particularly if you have ever been allergic to any drugs similar to rifaximin, or if you have other allergies that the consultant needs to be aware of.

Rifaximin can include inactive ingredients that might lead to allergic reactions and other issues. Before you use this medication, keep in mind that rifaximin can cause live vaccines using bacteria not to work as they should. It is important not to have any vaccinations or immunizations when you are using this medication unless your doctor advises otherwise. You should also inform your doctor or dentist about any medications that you are taking, including rifaximin tablets, before you have any procedure.

Do not take rifaximin tablets if you have other symptoms aside from diarrhoea, such as blood or mucus in your stool, or you have a significant fever. During pregnancy and nursing, this medication should only ever be used when it is absolutely necessary.

Make sure that you are getting the right treatment for your condition and discuss the benefits and risks with your doctor in depth before using rifaximin.

Does rifaximin interact with any other medications?

In some cases, taking two medications at the same time leads to them interacting poorly with each other. When drug interactions occur, one or more of the medications that you are using might stop working as they are supposed to. In some cases, drug interactions can also increase your chances of dangerous or severe side effects.

While there are few interactions currently listed for rifaximin, it is nevertheless important to tell your consultant about all of the medications that you are taking, including any substances that you have been prescribed by a doctor, as well as over- the-counter and herbal medications. Keep a list of all the non-prescription and prescription drugs that you take to help you. Do not change the dosage of any medicine you are using without approval.

Although it is unlikely that most antibiotics will affect hormonal birth control medications such as the patch or the contraceptive pill, some antibiotics may decrease their effectiveness. If you are using hormonal birth control at the same time as rifaximin tablets, you may want to ask your consultant whether it is safe to use this pill without an additional form of contraception.

Where can you buy rifaximin?

You can only buy this product by your pharmacy.

Can you get rifaximin without a prescription?

Antibiotics such as rifaximin are not available without a prescription.


BNF Nice, online, 2019 “Rifaximin” [accessed 20 November 2019] available on:, online, 2019 “Rifaximin” [accessed 20 November 2019] available on:, online, 2019 “Rifamixin” [accessed 20 November 2019] available on:

Medline plus, online, 2019, “Rifaximin”, [accessed 20 November 2019] available on:

Reviewed by:

Dr Imran Malik, General practitioner Registrationnumber: GMC: 4741365 Last checked: 14-08-2023 | Still valid

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