Carrie Yuan PharmD is a board-certified ambulatory care pharmacist. She is a clinical pharmacist in the Family Medicine Clinic at Harborview Medical Center in Seattle and a clinical associate professor at the University of Washington School of Pharmacy.

Alex Yampolsky, PharmD, is a clinical pharmacist at Elizabeth Seton Children’s Center, a pediatric long-term care facility in Yonkers, New York.

Dificid (fidaxomicin ) is a macrolide antimicrobial drug used to treat diarrhea associated with Clostridioides (formerly Clostridium) difficile (C. diff).

C. diff is a type of bacteria that can exist in your gastrointestinal (GI) tract (series of organs from the mouth to the anus). C. diff infection can occur when there is an imbalance of bacteria in your gut, allowing C. diff to grow and produce toxins. It is usually caused by taking antibiotics and being exposed to C. diff in a healthcare setting or in the community.

Dificid kills bacteria in the GI tract and prevents their growth. It inhibits bacterial RNA polymerase (an enzyme that copies information from DNA into an RNA sequence through transcription) to produce an antibacterial effect.

It is available as a prescription oral tablet and powder for oral suspension (liquid).

Dosage Form(s): Tablet, powder for suspension

The Food and Drug Administration (FDA) approved Dificid to treat Clostridioides difficile-associated diarrhea (CDAD) in adults and children aged 6 months and older. One of the main symptoms of C. diff infection is loose, watery stools (diarrhea) for several days.

To reduce the risk of developing drug-resistant bacteria, your healthcare provider will only prescribe Dificid for infections that are proven or strongly suspected to be caused by C. difficile. A positive stool test usually indicates C. diff.

Dificid will not treat colds, flu, or any other viral infections.

Take Dificid with or without food. Use tablets for children over 27.5 pounds (12.5 kilograms) who can swallow tablets whole. People who cannot swallow tablets or weigh less than 27.5 pounds should use the suspension.

For the oral suspension, the pharmacist will mix the liquid right before dispensing to you in a bottle. Take the bottle out of the refrigerator 15 minutes before administering. Make sure to shake vigorously before each use and measure the dose using the oral dosing syringe provided by your pharmacist.

Dificid is usually prescribed to take twice a day (about every 12 hours).

Store Dificid tablets at room temperature and protect them from light. Once mixed into a liquid, refrigerate the suspension at 36 degrees to 46 degrees Fahrenheit for 12 days. After 12 days, discard the medication.

This is not a complete list of side effects and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common side effects seen in adults include:

Side effects in children can include:

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

Dificid may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Dificid has not been studied in pregnancy in people. You and your healthcare provider will weigh the decision to use Dificid during pregnancy with the potential unknown risks and benefits to the pregnant person. Studies in rats and rabbits demonstrated no fetal harm.

It is not known if Dificid passes through breast milk. It is poorly absorbed orally, so it is expected that minimal amounts would reach the bloodstream of a nursing infant.

The safety and efficacy of Dificid have not been established in infants under 6 months of age. There is no difference in the safety or effectiveness of Dificid in older adults (aged 65 years and older) compared with younger adults.

Take a missed dose as soon as you remember. If it’s almost time for the next dose, skip the missed dose and take the next regularly scheduled dose. Do not double up to make up for the missed dose.

No cases of acute overdose with Dificid have been reported in people. Significant toxicity following an acute overdose of macrolide antibiotics is uncommon. If you take too much Dificid, treatment should be symptomatic and supportive.

If you think you or someone else may have overdosed on Dificid, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses, has a seizure, has trouble breathing, or can’t wake up after taking too much Dificid, call 911 immediately.

It is very important that your doctor check your progress after you finish taking this medicine. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it.

If your symptoms do not improve within a few days after you start this medicine or if they become worse, check with your doctor.

This medicine may cause serious allergic reactions, including angioedema. Angioedema can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this or if mild diarrhea continues or gets worse, check with your doctor.

Do not take Dificid if you are allergic to fidaxomicin or any other ingredients of Dificid, or if you are allergic to macrolides.

Allergic reactions can include the following symptoms:

No clinically significant drug-drug interactions have been identified.

Like Dificid, vancomycin also treats CDAD by killing and preventing the growth of bacteria. Dificid is not any less effective than vancomycin at treating C. diff infections, but it is better at decreasing rates of recurrent acute symptoms. Both drugs also have similar rates of side effects.

One advantage of Dificid is its twice-per-day dosing schedule compared with vancomycin, which needs to be taken four times a day.

Other medications in the same class of macrolides are azithromycin and erythromycin. However, these antibiotics are not approved for use in treating C. diff.

Dificid is used to treat C. difficile-associated diarrhea (CDAD) in adults and children 6 months and older.

Dificid derives from the fermentation of bacterium Dactylosporangium aurantiacum. Dactylosporangium aurantiacum inhibits RNA synthesis by binding to RNA polymerases and has antibacterial activity against C. diff. Dificid is minimally absorbed into the bloodstream. It works to kill bacteria in the gastrointestinal tract.

The most common side effects of Dificid are nausea, vomiting, abdominal pain, gastrointestinal bleeding, low red blood cell function (anemia), and low levels of a white blood cell type called neutrophils (neutropenia).

Dificid and vancomycin have similar efficacy in reducing the acute symptoms of CDAD with similar rates of unfavorable effects. Dificid may be better than vancomycin in reducing the recurrence of CDAD. Dificid is taken twice a day, while vancomycin is taken four times a day. Additionally, Dificid can be more costly compared to vancomycin.

Carefully monitor your CDAD symptoms while taking Dificid. If you have not noticed an improvement in symptoms (such as a reduction in the number of episodes of watery diarrhea per day) after finishing the 10-day course, contact your healthcare provider to discuss whether a change in treatment is necessary.

Frequently wash hands with soap and water to prevent the spread of C. difficile. Hand sanitizer does not kill C. difficile spores.

After your CDAD symptoms get better, watch for any recurrence of symptoms that may require further treatment. Contact your provider if you suspect a recurrence of CDAD.

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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Centers for Disease Control and Prevention. Healthcare-Associated Infections (HAIs). Clostridioides difficile Infection.

Zhanel GG, Walkty AJ, Karlowsky JA. Fidaxomicin: A novel agent for the treatment of Clostridium difficile infection. Can J Infect Dis Med Microbiol. 2015 Nov-Dec; 26(6): 305-312. doi: 10.1155/2015/934594

Food and Drug Administration. Dificid prescribing information.

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