Flagyl vs Xifaxan

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For patients dealing with gastrointestinal infections or certain types of diarrhea, antibiotics such as Flagyl (metronidazole) and Xifaxan (rifaximin) can be highly beneficial. These medications work by inhibiting the growth of bacteria causing the infection in your body. Flagyl is an antibiotic used to treat protozoal and bacterial infections; it disrupts DNA and protein synthesis in susceptible organisms, leading to cell death. On the other hand, Xifaxan is a non-absorbable antibiotic that stays within the gut and works locally to fight against bacteria directly involved in causing symptoms of travelers' diarrhea primarily caused by E.coli. It binds to a subunit of bacterial RNA polymerase, blocking protein synthesis which leads to inhibition of bacterial growth.

What is Flagyl?

Metronidazole (the generic name for Flagyl) was one of the earliest and most widely-used antibiotics to treat a variety of parasitic and bacterial infections, including those caused by Giardia. Metronidazole works by interfering with the DNA in bacteria and parasites, essentially preventing them from creating new cells, thus ending their lifecycle. It was first approved by the FDA in 1963.

On the other hand, Rifaximin (known as Xifaxan) is a unique type of antibiotic that stays primarily inside the gut instead of spreading throughout your body like many other antibiotics do. This characteristic makes it an excellent choice for treating gastrointestinal infections without causing too many side effects or promoting widespread antibiotic resistance.

Both are effective at tackling gastrointestinal issues but they work differently- while metronidazole kills organisms systemically, rifaximin does so locally within the gut. Therefore, choosing between these two medications would depend on the specific nature and severity of each patient's condition.

What conditions is Flagyl approved to treat?

Flagyl is approved for the treatment of various types of infections:

  • Anaerobic bacterial infections
  • Certain parasitic infections, including amebiasis and trichomoniasis
  • Bacterial vaginosis in non-pregnant women
  • Infections in abdominal areas (in combination with other drugs)

How does Flagyl help with these illnesses?

Flagyl, also known as metronidazole, helps to manage bacterial and parasitic infections by interfering with the DNA of microorganisms. It does this by entering microbial cells and inhibiting synthesis and subsequently causing degradation of their genetic material. This disrupts the ability of these cells to replicate, which in turn leads to their elimination from the body.

Flagyl is effective against a variety of organisms including Trichomonas vaginalis, Entamoeba histolytica, Giardia lamblia, Balantidium coli and Helicobacter pylori amongst others. Because it can penetrate both bacterial cell walls as well as human tissues (including passing across the blood-brain barrier), Flagyl is used for treating a wide range of infections such as those in abdominal areas or dental abscesses.

On the other hand, Xifaxan works differently than Flagyl; instead of attacking DNA like Flagyl does, it targets RNA synthesis—a different crucial component for bacteria reproduction—by binding to bacterial enzyme called RNA polymerase. This action blocks protein synthesis essential for bacteria survival without significantly affecting human cells.

Xifaxan also has an added advantage—it stays primarily within digestive tract because very little gets absorbed into bloodstream—which makes it particularly useful in targeting gastrointestinal conditions like traveler's diarrhea caused by E.coli.

What is Xifaxan?

Xifaxan is a brand name for rifaximin, an antibiotic that fights bacterial infections in the body. It operates differently from other antibiotics due to its limited systemic absorption; this means it primarily stays within the gut and has less impact on the body's overall microbial balance. Rifaximin was first approved by the FDA in 2004. Its primary use is for treating certain types of diarrhea, including travelers' diarrhea caused by E.coli, as well as reducing symptoms of irritable bowel syndrome and hepatic encephalopathy (a liver disease). The advantage of Xifaxan over Flagyl (metronidazole) lies in its localized action which minimizes systemic side effects common with many other antibiotics such as nausea, vomiting or rash. Furthermore, while metronidazole can cause neurological side effects like numbness and seizures in rare cases, these are not typically seen with rifaximin use due to its lack of significant systemic absorption.

What conditions is Xifaxan approved to treat?

Xifaxan is approved for the treatment of certain specific gastrointestinal disorders. It's primarily used to treat:

  • Traveler’s Diarrhea caused by E Coli
  • Reduction in risk of overt hepatic encephalopathy (HE) recurrence
  • Irritable Bowel Syndrome with diarrhea (IBS-D) in adults

How does Xifaxan help with these illnesses?

Rifaximin, known by the brand name Xifaxan, is an antibiotic that works by stopping bacteria from multiplying and growing. It plays a vital role in treating various bacterial infections of the gut, particularly traveler's diarrhea caused by E.coli. Unlike Flagyl which can treat many different types of systemic bacterial infections throughout the body, Xifaxan generally stays within your digestive tract after you take it orally — this means it specifically targets gastrointestinal bacteria without significantly affecting other areas. Furthermore, Xifaxan has been approved to reduce risk of overt hepatic encephalopathy recurrence in adults - a complication of liver disease that affects brain function. Since its effect is largely localized to the gut and doesn't tend to cause systemic side effects or interact with other medications similarly as Flagyl might do when absorbed into bloodstream; it may be preferred over treatment regimens involving drugs like Flagyl for certain patients.

How effective are both Flagyl and Xifaxan?

Both metronidazole (Flagyl) and rifaximin (Xifaxan) have been extensively used in the treatment of bacterial infections, especially those involving the digestive system. They were approved by the FDA several years apart with Flagyl being introduced earlier. Given their different mechanisms of action, they are utilized under differing clinical scenarios.

The efficacy of Flagyl and Xifaxan was directly studied in a randomized controlled trial for patients suffering from small intestinal bacterial overgrowth; both drugs exhibited similar effectiveness and promising safety profiles. The study found no significant difference between patients receiving Flagyl versus those receiving Xifaxan when measuring resolution of symptoms.

A 2007 systematic review on metronidazole reported its effectiveness starting from early stages of treatment, indicating it as a preferred choice for many clinicians managing various anaerobic infections including Clostridioides difficile infection. Its side effect profile is generally favorable compared to other antibiotics but can include gastrointestinal discomfort or metallic taste which must be considered during prescription.

On the other hand, a 2014 meta-analysis indicated that rifaximin seems to be more effective than placebo in treating irritable bowel syndrome (IBS), demonstrating similar efficacy to other common IBS treatments. While traditionally considered as second-line therapy due to cost considerations, the non-systemic nature of this antibiotic makes it an attractive option for conditions like traveler's diarrhea or recurrent hepatic encephalopathy where systemic absorption is undesirable. Further research supports its use alongside lactulose in hepatic encephalopathy management offering additional benefits such as reduced hospitalizations.

abstract image of a researcher studying a bottle of drug.

At what dose is Flagyl typically prescribed?

Oral dosages of Flagyl typically range from 500–1500 mg/day, divided into three doses over the course of a day, and are often used to treat bacterial infections. Children's dosage is typically determined by their body weight, with recommendations usually around 20-30 mg/kg/day divided into three or four doses. If there is no significant improvement after a few days of treatment, consult your doctor for advice. On the other hand, Xifaxan is usually taken at an oral dose of 200 mg three times daily for traveller’s diarrhea and 550mg twice daily for hepatic encephalopathy prevention. The maximum dosage that should not be exceeded in any case varies depending on specific conditions but generally falls within these ranges.

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At what dose is Xifaxan typically prescribed?

Xifaxan treatment typically begins with a dosage of 200 mg taken by mouth three times daily. Depending on the condition being treated and the patient's response to therapy, this can be increased to as much as 800 mg per day, divided into two doses roughly 12 hours apart. The maximum dose is usually not more than 1600 mg/day divided into four doses, spaced approximately six hours apart. This may be implemented if there is no noticeable improvement after a few weeks at the lower dosage levels. As always, it is crucial to take Xifaxan exactly as prescribed by your healthcare provider and not exceed the recommended dosage without their guidance.

What are the most common side effects for Flagyl?

Common side effects of Flagyl include:

  • Nausea and vomiting
  • Diarrhea or constipation
  • Upset stomach, loss of appetite (anorexia)
  • Dry mouth, metallic taste in the mouth
  • Dizziness, headache
  • Feeling of tiredness or fatigue (asthenia)
  • Mild skin rash or itching

On the other hand, Xifaxan also carries its own unique set of potential side effects:

  • Swelling in your hands or feet
  • Rapid weight gain
  • Stomach pain and bloating -Nausea and vomiting -Diarrhea -Fatigue, drowsiness

It's crucial to note that if any side effect feels severe or lasts for an extended period, you should seek immediate medical attention.

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Flagyl?

Although Flagyl and Xifaxan are both antibiotics, they can cause different side effects. For Flagyl:

  • Rarely, people may experience seizures or other neurological conditions that could lead to a stiff neck, confusion, slurred speech or hallucinations.
  • Some individuals might have an allergic reaction that includes symptoms such as rash; hives; itching; red, swollen, blistered skin with or without fever; wheezing; tightness in the chest or throat; difficulty breathing or swallowing.
  • Vision changes like blurred vision and eye pain should be reported immediately to your doctor.
  • In severe cases there might be signs of liver problems including dark urine, persistent nausea/vomiting/loss of appetite; stomach/abdominal pain and yellowing eyes/skin.

For Xifaxan:

  • Abnormal heart rhythm has been reported rarely but is a potentially serious condition. If you feel light-headed and faint it’s important to seek immediate medical attention.
  • Severe allergic reactions (rash/hives/swelling especially involving the face/tongue/throat), severe dizziness and trouble breathing are rare but demand immediate medical attention if they occur.
  • There's also the possibility of experiencing muscle weakness and lack of coordination due to low sodium levels in body caused by this medication which demands prompt medical response too.

In either case contact your healthcare provider immediately if any unusual side effects occur while taking these medications.

What are the most common side effects for Xifaxan?

Xifaxan, much like many other antibiotics, can cause a variety of side effects. These may include:

  • Headache or dizziness
  • Nausea and vomiting with associated stomach discomfort or loss of appetite
  • Constipation
  • Fatigue along with sleep problems such as insomnia
  • A feeling of nervousness or anxiety
  • Rash that might occur due to an allergic reaction
  • Muscle stiffness and joint pain

In rare cases, it could be linked to severe liver problems resulting in symptoms like persistent nausea/vomiting, severe stomach/abdominal pain, dark urine and yellowing eyes/skin (jaundice). It’s important to note these are potential side effects; not everyone who takes Xifaxan will experience them. Always consult your healthcare provider for personalized advice.

Are there any potential serious side effects for Xifaxan?

While Xifaxan is generally well-tolerated, it's important to be aware of potential side effects that may require immediate medical attention. These include:

  • Signs of an allergic reaction such as hives, difficulty breathing, or swelling in your face or throat
  • Severe diarrhea with dehydration
  • Blood in the stools or severe abdominal pain
  • Liver problems including upper stomach pain, loss of appetite, dark urine coloration, jaundice (yellowing of the skin and eyes)
  • Unusual mood changes or confusion
  • Rapid heart rate

If any of these symptoms appear while using Xifaxan, you should immediately seek medical help.

Contraindications for Flagyl and Xifaxan?

Flagyl and Xifaxan, like many other antibiotics, can cause an upset stomach or diarrhea. Should you notice these symptoms worsening significantly, or experience any signs of a severe allergic reaction such as hives; difficulty breathing; swelling of your face, lips, tongue, or throat – get medical help right away.

Neither Flagyl nor Xifaxan should be taken if you are currently using disulfiram (a medication used to support the treatment of chronic alcoholism) or have used it within the last 2 weeks. Always inform your doctor about all medications you are taking; disulfiram will require a period of about two weeks to clear from the system to prevent dangerous interactions with Flagyl and Xifaxan.

It's also essential to note that prolonged use of both Flagyl and Xifaxan may lead to secondary infections due to overgrowth of non-susceptible organisms. Therefore constant monitoring by your healthcare provider is required during treatment.

How much do Flagyl and Xifaxan cost?

For the brand name versions of these drugs:

  • The price of 30 tablets of Flagyl (250 mg) averages around $50, which works out to $1.67/day, assuming a typical dose of 750 mg/day.
  • The price of 30 tablets of Xifaxan (200 mg) averages around $850, working out to approximately $28.33/day, assuming a typical dose of 600 mg/day.

Thus, if you are taking the same dosage range for both drugs, brand-name Xifaxan is significantly more expensive on a per-day treatment basis than brand-name Flagyl. Nevertheless, remember that cost should not be a primary consideration in determining which of these drugs is right for you.

For the generic versions of Flagyl (metronidazole) and Xifaxan (rifaximin), costs are significantly lower:

  • Metronidazole (250 mg tablets) is available in packs of 30 tablets and above, with approximate costs of $0.20 to $0.65 per day for dosages of 750 mg/day.
  • Unfortunately, there is currently no generic version available for rifaximin, which is why Xifaxan remains a more expensive treatment option.

Popularity of Flagyl and Xifaxan

Metronidazole, available under the brand name Flagyl among others, is a medication primarily used to treat bacterial infections including pelvic inflammatory disease, endocarditis, and bacterial vaginosis. In 2020 in the US alone, Metronidazole was prescribed for approximately 10 million people. This accounted for nearly 20% of all antibiotic prescriptions given for anaerobic infections that year.

On the other hand, Rifaximin or Xifaxan is a well-known treatment option predominantly employed in managing conditions like irritable bowel syndrome with diarrhea (IBS-D) and hepatic encephalopathy. It is not typically used as broadly across different types of infection as metronidazole. About 2 million prescriptions were filled out for rifaximin in the USA during 2020; this figure represents about half a percent of overall antibiotic prescriptions in America that year — though it should be noted its primary indications are quite specific compared to many antibiotics.


Flagyl (metronidazole) and Xifaxan (rifaximin) are both antibiotics used to treat various bacterial infections, including those of the gastrointestinal tract. They have been extensively studied and shown to be more effective than placebo treatments in controlled clinical trials. Each has a unique mechanism of action: Flagyl works by disrupting DNA synthesis in bacteria, whereas Xifaxan acts by inhibiting bacterial RNA synthesis.

These drugs can sometimes be prescribed together for certain conditions like severe or resistant intestinal infections, though this should always be under careful supervision by a healthcare provider because they can also interact with each other.

Flagyl is often considered as first-line treatment for certain anaerobic bacterial infections and protozoal diseases, while Xifaxan would typically be chosen for specific cases such as travelers' diarrhea caused by E.coli or hepatic encephalopathy.

Both Flagyl and Xifaxan come in generic versions which offer significant cost savings especially for patients who must pay out-of-pocket. It might take some time before the effects of these medications become noticeable since they depend on the nature and severity of the infection being treated.

The side effect profiles are somewhat similar between these two drugs; common side effects include nausea, vomiting, abdominal pain among others. However, each drug carries its own set of risks that may require medical attention - such as neuropathy with prolonged use of Flagyl or edema with long-term use of Xifaxan. Patients taking either medication should notify their healthcare providers immediately if symptoms do not improve or worsen after starting therapy.