Fidaxomicin is taken as an oral tablet. To ensure that you get the full benefit of the medicine, it is important to take it exactly as prescribed by your doctor.

Instructions for Use:

1. Take fidaxomicin exactly as directed by your healthcare provider. The typical dosage is 200 mg twice a day.
   
   
2. Do not chew or crush the tablet. Swallow the tablet whole with a full glass of water.
   
   
3. It can be taken with or without food. However, if it upsets your stomach, taking it with food may help.
   
   
4. Complete the entire course of treatment, even if you start feeling better before finishing the medicine. Stopping the medication too early may allow the infection to return.
   
   

Important Tips:

• If you miss a dose, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose—do not take two doses at once.
  
  

If you experience persistent diarrhea, let your doctor know, as this could indicate an issue with the treatment or a possible recurrence of the infection.

Fidaxomicin works by inhibiting bacterial RNA polymerase, an enzyme needed by C. difficile to make copies of its genetic material. Without the ability to reproduce, the C. difficile bacteria cannot spread or increase in number, allowing the immune system to fight off the infection more effectively.

Mechanism of Action:

• Fidaxomicin works by binding to the RNA polymerase enzyme in C. difficile.
  
  
• This binding stops the bacteria from producing proteins needed for survival and growth.
  
  
• The bacteria are unable to multiply and die off, allowing the body’s natural defenses to clear the infection.
  
  

What makes fidaxomicin different from many other antibiotics is its specificity for C. difficile. It is designed to work primarily in the intestines, where C. difficile infections are most common. This minimizes disruption to the rest of the body’s microbiome (the natural collection of bacteria and other microorganisms that live in the body).

Fidaxomicin is generally well-tolerated, but, like any medication, it can cause side effects in some people. Most side effects are mild, but it’s important to be aware of any unusual symptoms.

Common Side Effects:

• Nausea or vomiting
  
  
• Stomach pain or discomfort
  
  
• Diarrhea (though this could also be a sign of the infection itself)
  
  
• Headache
  
  

These side effects are generally mild and may go away after a few days of treatment.

Serious Side Effects (Less Common):

• Allergic reactions, such as skin rash, itching, or swelling, especially around the face or throat.
  
  
• Severe diarrhea (not related to the infection) may indicate a condition called pseudomembranous colitis, which is an inflammation of the colon.
  
  
• Liver problems: Rarely, fidaxomicin may cause liver issues, so your doctor may monitor your liver function during treatment.
  
  

If you experience any severe side effects such as trouble breathing, severe abdominal pain, or a rash, contact your healthcare provider immediately.

Before starting fidaxomicin, there are a few important precautions and warnings to keep in mind:

Use with Caution If:

• You have liver disease or kidney disease. Although fidaxomicin is not heavily processed by the liver or kidneys, these organs may still be affected, and your doctor may want to monitor you closely during treatment.
  
  
• You are allergic to fidaxomicin or any of its components. Inform your healthcare provider of any allergies before beginning treatment.
  
  

Do Not Use If:

• You have a severe allergic reaction to fidaxomicin or other antibiotics in the same class.
  
  
• You have a history of Clostridium difficile infection that is not related to antibiotic use, as this may indicate a more complicated infection that requires different treatment.
  
  

It’s important to take the full course of fidaxomicin as prescribed, even if you start feeling better. Stopping the medication too soon can result in the infection returning.

Fidaxomicin has relatively few drug interactions, but there are still some important things to be aware of:

• Cyclosporine: If you are taking cyclosporine (an immunosuppressive drug), your doctor may adjust the dose of fidaxomicin, as this combination may increase the levels of fidaxomicin in the blood.
  
  
• Antibiotics: Be cautious when using other antibiotics during or right after fidaxomicin treatment, as they can interfere with its effectiveness or increase the risk of further infection.
  
  

Always inform your doctor about any other medications you are taking, including over-the-counter drugs, vitamins, and herbal supplements. This ensures that any potential interactions can be carefully managed.

Fidaxomicin is typically prescribed in the following dosage:

• Adults: The recommended dose is 200 mg twice a day for 10 days.
  
  
• Children: Fidaxomicin is not typically recommended for children, unless your doctor advises it for specific cases.
  
  

The dosage may vary depending on the severity of the infection or the patient’s health condition. Your doctor will determine the appropriate dose based on your individual needs and the extent of the infection.

Fidaxomicin is a prescription-only medication and is not available over-the-counter. A doctor or healthcare provider must evaluate your condition and decide if fidaxomicin is the best treatment for your C. difficile infection.

Getting a Prescription:

• If you are diagnosed with C. difficile, your doctor will evaluate your symptoms and medical history before prescribing fidaxomicin.
  
  
• The doctor may also perform tests to ensure that C. difficile is the cause of the symptoms and that fidaxomicin is the appropriate choice for treatment.

• What is Fidaxomicin used for?
  It is used to treat Clostridioides difficile–associated diarrhea (CDAD), a bacterial infection of the colon that can cause severe diarrhea and inflammation.
  Fidaxomicin is prescribed for adults and children (≥6 months) with confirmed C. diff infection.

• What are the brand names?

  • Dificid® (U.S.)

  • Dificlir® (international)

• What is the active ingredient?
  Fidaxomicin, a macrolide antibiotic (structurally related to macrolides but with unique activity).

• How does Fidaxomicin work?

  • It inhibits bacterial RNA polymerase, blocking RNA synthesis in C. difficile bacteria.

  • This stops bacterial growth and spore production, helping restore normal gut flora.

  • It works locally in the intestines, with minimal systemic absorption — reducing side effects and recurrence risk.

• What type of medication is it?
  A macrolide-class, narrow-spectrum antibacterial — designed specifically for C. difficile infections.

• How is Fidaxomicin taken?

  • By mouth, with or without food.

  • Usually 200 mg twice daily (every 12 hours) for 10 days.

  • Swallow tablets whole with water; do not crush or chew.

• What forms does it come in?

  • Tablets: 200 mg

  • Oral suspension (powder for reconstitution): 40 mg/mL (for children ≥6 months)

• How long does Fidaxomicin take to work?
  Symptoms often improve within 2–3 days, but the full 10-day course must be completed to prevent recurrence.

• What are the common side effects?

  • Nausea or vomiting

  • Abdominal pain or bloating

  • Diarrhea (mild, transient)

  • Headache

  • Anemia or low red blood cell count (rare)

• Are there serious side effects?
  Rare, but possible:

  • Allergic reactions (rash, itching, swelling, difficulty breathing)

  • Severe diarrhea after treatment (possible recurrence of C. diff or other infection)

  • Liver enzyme elevations (rare — monitor if liver disease is present)

• Who should not take Fidaxomicin?

  • People allergic to fidaxomicin or other macrolides (e.g., erythromycin, clarithromycin).

  • Use with caution in patients with significant hepatic impairment.

• Can Fidaxomicin cause recurrence prevention?
  Yes — it has a lower recurrence rate than vancomycin because it spares normal gut flora, reducing re-infection risk.

• Can Fidaxomicin be taken with food?
  Yes — food does not affect absorption.

• Can Fidaxomicin be used during pregnancy?

  • Limited data, but animal studies show no harm to the fetus.

  • Should be used only if clearly needed.

• Can it be taken while breastfeeding?
  Yes — minimal absorption means low risk to infants, but consult your doctor before use.

• Does Fidaxomicin interact with other medications?

  • Very few interactions, as it’s not systemically absorbed.

  • However, avoid use with strong P-glycoprotein inhibitors (e.g., cyclosporine) unless necessary — they may increase gut exposure.

• Can Fidaxomicin cause resistance?
  Low risk — its narrow spectrum reduces the likelihood of antibiotic resistance.

• What if I miss a dose?
  Take it as soon as you remember, unless it’s almost time for your next dose — don’t double up.

• Can Fidaxomicin treat infections other than C. diff?
  No — it is not effective for other bacterial infections. Its activity is specific to C. difficile in the colon.

• How should I store Fidaxomicin?

  • Store tablets at 20°C–25°C (68°F–77°F).

  • Store oral suspension powder at room temperature and use within 12 days of mixing.

• Is there a generic version available?
  Yes — generic Fidaxomicin is now available.

• Where can I get Fidaxomicin?
  Available by prescription only from pharmacies and hospitals.