Does Dificid (fidaxomicin) cause side effects?
Dificid (fidaxomicin) is a macrolide antibiotic used in adults (18 years of age and older) to treat Clostridium difficile-associated diarrhea (CDAD). To reduce the development of drug-resistant bacteria and maintain the effectiveness of Dificid and other antibacterial drugs, Dificid should be used only to treat infections that are proven or strongly suspected to be caused by Clostridium difficile.
Common side effects of Dificid include
- nausea,
- vomiting,
- abdominal pain,
- gastrointestinal bleeding,
- anemia, and
- low white blood cells (neutropenia).
Serious side effects of Dificid include
- fever,
- chills,
- body aches,
- flu symptoms,
- sores in the mouth and throat;
- pale skin,
- lightheadedness, or shortness of breath,
- rapid heart rate,
- trouble concentrating;
- black, bloody, or tarry stools; or
- coughing up blood or vomit that looks like coffee grounds.
There are no listed drug interactions of Dificid.
There are no adequate and well-controlled studies of Dificid in pregnant women. Dificid should be used during pregnancy only if clearly needed.
It is unknown if Dificid is excreted in breast milk. Because many drugs are excreted in human milk, caution should be exercised when Dificid is administered to a breastfeeding woman.
What are the important side effects of Dificid (fidaxomicin)?
- nausea (11%),
- vomiting (7%),
- abdominal pain (6%),
- gastrointestinal hemorrhage (4%),
- anemia (2%), and
- neutropenia (2%).
Because clinical trials are conducted under widely varying conditions, adverse event rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of any other drug and may not reflect the rates observed in practice. The safety of Dificid 200 mg tablets taken twice a day for 10 days was evaluated in 564 patients with CDAD in two active-comparator controlled trials with 86.7% of patients receiving a full course of treatment.
Thirty-three patients receiving Dificid (5.9%) withdrew from trials as a result of adverse reactions (AR). The types of AR resulting in withdrawal from the study varied considerably. Vomiting was the primary adverse reaction leading to discontinuation of dosing; this occurred at an incidence of 0.5% in both the fidaxomicin and vancomycin patients in Phase 3 studies.
The following adverse reactions were reported in <2% of patients taking Dificid tablets in controlled trials:
Gastrointestinal Disorders:
- abdominal distension,
- abdominal tenderness,
- dyspepsia,
- dysphagia,
- flatulence,
- intestinal obstruction,
- megacolon
Investigations:
- increased blood alkaline phosphatase,
- decreased blood bicarbonate,
- increased hepatic enzymes,
- decreased platelet count
Metabolism and Nutrition Disorders:
- hyperglycemia,
- metabolic acidosis
Skin and Subcutaneous Tissue Disorders:
- drug eruption,
- pruritus,
- rash
Dificid (fidaxomicin) side effects list for healthcare professionals
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
The safety of Dificid 200 mg tablets taken twice a day for 10 days was evaluated in 564 patients with CDAD in two active-comparator controlled trials with 86.7% of patients receiving a full course of treatment.
Thirty-three patients receiving Dificid (5.9%) withdrew from trials as a result of adverse reactions (AR). The types of AR resulting in withdrawal from the study varied considerably. Vomiting was the primary adverse reaction leading to discontinuation of dosing; this occurred at an incidence of 0.5% in both the fidaxomicin and vancomycin patients in Phase 3 studies.
Table 1: Selected Adverse Reactions with an Incidence
of ≥2% Reported in Dificid Patients in Controlled
System Organ Class Preferred Term |
Dificid (N=564) n (%) |
Vancomycin (N=583) n (%) |
Blood and Lymphatic System Disorders | ||
Anemia | 14 (2%) | 12 (2%) |
Neutropenia | 14 (2%) | 6 (1%) |
Gastrointestinal Disorders | ||
Nausea | 62 (11%) | 66 (11%) |
Vomiting | 41 (7%) | 37 (6%) |
Abdominal Pain | 33 (6%) | 23 (4%) |
Gastrointestinal Hemorrhage | 20 (4%) | 12 (2%) |
The following adverse reactions were reported in <2% of patients taking Dificid tablets in controlled trials:
- Gastrointestinal Disorders: abdominal distension, abdominal tenderness, dyspepsia, dysphagia, flatulence, intestinal obstruction, megacolon
- Investigations: increased blood alkaline phosphatase, decreased blood bicarbonate, increased hepatic enzymes, decreased platelet count
- Metabolism and Nutrition Disorders: hyperglycemia, metabolic acidosis
- Skin and Subcutaneous Tissue Disorders: drug eruption, pruritus, rash
Post Marketing Experience
Adverse reactions reported in the post marketing setting arise from a population of unknown size and are voluntary in nature. As such, reliability in estimating their frequency or in establishing a causal relationship to drug exposure is not always possible.
Hypersensitivity reactions (dyspnea, angioedema, rash, and pruritus) have been reported.
What drugs interact with Dificid (fidaxomicin)?
- Fidaxomicin and its main metabolite, OP-1118, are substrates of the efflux transporter, P-glycoprotein (P-gp), which is expressed in the gastrointestinal tract.
Cyclosporine
- Cyclosporine is an inhibitor of multiple transporters, including P-gp. When cyclosporine was co-administered with Dificid, plasma concentrations of fidaxomicin and OP-1118 were significantly increased but remained in the ng/mL range.
- Concentrations of fidaxomicin and OP-1118 may also be decreased at the site of action (i.e., gastrointestinal tract) via P-gp inhibition; however, concomitant P-gp inhibitor use had no attributable effect on safety or treatment outcome of fidaxomicin-treated patients in controlled clinical trials.
- Based on these results, fidaxomicin may be co-administered with P-gp inhibitors and no dose adjustment is recommended.
Summary
Dificid (fidaxomicin) is a macrolide antibiotic used in adults (18 years of age and older) to treat Clostridium difficile-associated diarrhea (CDAD). Common side effects of Dificid include nausea, vomiting, abdominal pain, gastrointestinal bleeding, anemia, and low white blood cells (neutropenia). There are no listed drug interactions of Dificid. There are no adequate and well-controlled studies of Dificid in pregnant women. It is unknown if Dificid is excreted in breast milk.
Multimedia: Slideshows, Images & Quizzes
Related Disease Conditions
-
Diarrhea
Diarrhea is a change in the frequency and looseness of bowel movements. Symptoms associated with diarrhea are cramping, abdominal pain, and the sensation of rectal urgency. Causes of diarrhea include viral, bacterial, or parasite infection, gastroenteritis, food poisoning, and drugs. Absorbents and anti-motility medications are used to treat diarrhea.
-
IBS-D (Irritable Bowel Syndrome with Diarrhea)
IBS-D or irritable bowel syndrome with diarrhea refers to IBS with diarrhea. Symptoms of IBS-D include intestinal gas (flatulence), loose stools, frequent stools, abdominal pain, diarrhea, and nausea. New non-FDA approved IBS tests may help diagnose IBS and IBS-D. Treatment of IBS-D is geared to toward managing symptoms with diet, medication, and lifestyle changes.
-
Is C. diff (Clostridium difficile) Contagious?
C. diff, or Clostridium difficile, is a bacteria that infects the colon. C. diff bacteria can be found on furniture, bathroom floors, telephones, fingernails, jewelry, toilet seats, and other places. Symptoms of C. diff infection are fever, abdominal pain, and cramps; however, not all people infected with C. diff have symptoms. Treatments for C. diff are antibiotics and surgery in some cases.
-
Travelers' Diarrhea
Travelers' diarrhea is generally contracted by eating contaminated food or drinking contaminated water. Food is the primary source of travelers' diarrhea. Enterotoxigenic E. coli is the cause of up to 70% of all cases of travelers' diarrhea. There are five unique classes of E. coli that causes gastroenteritis. Other bacteria responsible for travelers' diarrhea include Campylobacter, jejuni, shigella, and salmonella. Viruses such as rotavirus and Norwalk virus (norovirus) and giardia lamblia a parasite may cause travelers' diarrhea. Prevention is careful eating and drinking of water.
-
Clostridium Difficile Colitis (C. diff, C. difficle Colitis)
Clostridium difficile (C. difficile) is a bacterium, and is one of the most common causes of infection of the colon. C. difficile spores are found frequently in hospitals, nursing homes, extended care facilities, and nurseries for newborn infants.
-
How Do You Get Rid of Diarrhea?
Diarrhea is characterized as loose or runny stools that happen an abnormally high number of times throughout the day. Diarrhea can be linked to autoimmune diseases like Crohn’s or irritable bowel syndrome but is more often a sign of food intolerance (lactose is common), viral infection, food poisoning or other infectious diseases of varying severity.
-
What Can Diarrhea Be a Sign Of?
Diarrhea is a common condition and usually goes away without intervention.
Treatment & Diagnosis
- 9 Tips to Prevent Travelers' Diarrhea
- Diarrhea: Moms Uninformed About Rotavirus Illness
- IBS diarrhea treatment: Questran and Colestid
- Diarrhea: On The Go Diarrhea
- Can You Develop Lactose Intolerance as You Age?
- What Does Bloody Diarrhea in Toddlers Mean?
- How to Stop Diarrhea
- How to Stop Diarrhea
- Does Stress Cause Diarrhea or Constipation?
- How Do I Get Rid of Diarrhea from Gallbladder Removal?
- When to Call the Doctor for Fever, Nausea, Diarrhea, Colds, and Coughs
Medications & Supplements

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.