Side Effects of Omnicef (cefdinir)

Omnicef (cefdinir) is a semi-synthetic cephalosporin antibiotic used to treat susceptible bacteria causing infections of the middle ear (otitis media), tonsils (tonsillitis), throat (strep throat), larynx (laryngitis), sinuses (sinusitis), bronchi (bronchitis), lungs (pneumonia), and skin and other soft tissues. The brand name Omnicef has been discontinued in the U.S.

Common side effects of Omnicef include

• diarrhea or loose stools,
• nausea,
• abdominal pain,
• vaginal yeast infection,
• vaginitis,
• vomiting,
• rash, and
• headache.

Rare side effects of Omnicef include

• abnormal liver tests,
• allergic reactions,
• abnormal stool,
• constipation, and
• dry mouth.

Serious side effects of Omnicef include

• pseudomembranous colitis (Clostridium difficile colitis), a potentially serious bacterial infection of the colon. Symptoms include
  • diarrhea,
  • fever,
  • abdominal pain, and possibly
  • shock.

Drug interactions of Omnicef include aluminum or magnesium containing antacids, which reduce the absorption of Omnicef from the intestine. Separating the administration of Omnicef and such antacids by two hours prevents this interaction.

• Iron supplements also reduce the absorption of Omnicef.
• Separating the administration of Omnicef and iron supplements by two hours prevents this interaction.
• There have been reports of reddish stool in patients who have received Omnicef. This could be due to the formation of a chemical complex between Omnicef and iron in the stomach. 

There are no adequate studies of Omnicef in pregnant women. Omnicef is not secreted in breast milk. Consult your doctor before breastfeeding. 

• Cefdinir generally is well tolerated. The most common side effects are:
  • Diarrhea or loose stools
  • Nausea
  • Abdominal pain
  • Vaginal moniliasis
  • Vaginitis
  • Vomiting
  • Rash
  • Headache
• Rare side effects include:
  • Abnormal liver tests
  • Allergic reactions
  • Abnormal stool
  • Constipation
  • Dry mouth
• Cefdinir may cause false test results with some tests for sugar in the urine.
• Like most antibiotics, cefdinir may cause a condition called pseudomembranous colitis (Clostridium difficile colitis), a potentially serious bacterial infection of the colon. Patients who develop signs of pseudomembranous colitis after starting cefdinir (diarrhea, fever, abdominal pain, and possibly shock) should contact their doctor immediately.
• Persons who are allergic to the penicillin class of antibiotics, for example, amoxicillin, amoxicillin and clavulanic acid (Augmentin), which are related to cephalosporins, may or may not be allergic to cephalosporins.

Adverse Events

Clinical Trials - OMNICEF Capsules (Adult and Adolescent Patients)

• In clinical trials, 5093 adult and adolescent patients (3841 US and 1252 non-US) were treated with the recommended dose of cefdinir capsules (600 mg/day). Most adverse events were mild and self-limiting. No deaths or permanent disabilities were attributed to cefdinir.
• One hundred forty-seven of 5093 (3%) patients discontinued medication due to adverse events thought by the investigators to be possibly, probably, or definitely associated with cefdinir therapy.
• The discontinuations were primarily for gastrointestinal disturbances, usually diarrhea or nausea. Nineteen of 5093 (0.4%) patients were discontinued due to rash thought related to cefdinir administration.
• In the US, the following adverse events were thought by investigators to be possibly, probably, or definitely related to cefdinir capsules in multiple-dose clinical trials (N = 3841 cefdinir-treated patients):

ADVERSE EVENTS ASSOCIATED WITH CEFDINIR CAPSULES US TRIALS IN ADULT AND ADOLESCENT PATIENTS (N = 3841)^a

The following laboratory value changes of possible clinical significance, irrespective of relationship to therapy with cefdinir, were seen during clinical trials conducted in the US:

LABORATORY VALUE CHANGES OBSERVED WITH CEFDINIR CAPSULES US TRIALS IN ADULT AND ADOLESCENT PATIENTS (N = 3841)

Clinical Trials - OMNICEF For Oral Suspension (Pediatric Patients)

• In clinical trials, 2289 pediatric patients (1783 US and 506 non-US) were treated with the recommended dose of cefdinir suspension (14 mg/kg/day).
• Most adverse events were mild and self-limiting. No deaths or permanent disabilities were attributed to cefdinir.
• Forty of 2289 (2%) patients discontinued medication due to adverse events considered by the investigators to be possibly, probably, or definitely associated with cefdinir therapy.
• Discontinuations were primarily for gastrointestinal disturbances, usually diarrhea. Five of 2289 (0.2%) patients were discontinued due to rash thought related to cefdinir administration.
• In the US, the following adverse events were thought by investigators to be possibly, probably, or definitely related to cefdinir suspension in multiple-dose clinical trials (N = 1783 cefdinirtreated patients):

ADVERSE EVENTS ASSOCIATED WITH CEFDINIR SUSPENSION US TRIALS IN PEDIATRIC PATIENTS (N = 1783)^a

• NOTE: In both cefdinir- and control-treated patients, rates of diarrhea and rash were higher in the youngest pediatric patients.
• The incidence of diarrhea in cefdinir-treated patients ≤ 2 years of age was 17% (95/557) compared with 4% (51/1226) in those > 2 years old.
• The incidence of rash (primarily diaper rash in the younger patients) was 8% (43/557) in patients ≤ 2 years of age compared with 1% (8/1226) in those > 2 years old.
• The following laboratory value changes of possible clinical significance, irrespective of relationship to therapy with cefdinir, were seen during clinical trials conducted in the US:

LABORATORY VALUE CHANGES OF POSSIBLE CLINICAL SIGNIFICANCE OBSERVED WITH CEFDINIR SUSPENSION US TRIALS IN PEDIATRIC PATIENTS (N = 1783)

Postmarketing Experience

The following adverse experiences and altered laboratory tests, regardless of their relationship to cefdinir, have been reported during extensive postmarketing experience, beginning with approval in Japan in 1991:

• shock,
• anaphylaxis with rare cases of fatality,
• facial and laryngeal edema,
• feeling of suffocation,
• serum sickness-like reactions,
• conjunctivitis,
• stomatitis,
• Stevens-Johnson syndrome,
•  toxic epidermal necrolysis,
• exfoliative dermatitis,
•  erythema multiforme,
• erythema nodosum,
•  acute hepatitis,
• cholestasis,
• fulminant hepatitis,
•  hepatic failure,
•  jaundice,
• increased amylase,
• acute enterocolitis,
• bloody diarrhea,
• hemorrhagic colitis,
• melena,
• pseudomembranous colitis,
• pancytopenia,
• granulocytopenia,
•  leukopenia,
• thrombocytopenia,
• idiopathic thrombocytopenic purpura,
• hemolytic anemia,
• acute respiratory failure,
• asthmatic attack,
• drug-induced pneumonia,
• eosinophilic pneumonia,
• idiopathic interstitial pneumonia,
• fever,
•  acute renal failure,
• nephropathy,
• bleeding tendency,
• coagulation disorder,
• disseminated intravascular coagulation,
• upper GI bleed,
• peptic ulcer,
•  ileus,
•  loss of consciousness,
• allergic vasculitis,
• possible cefdinir-diclofenac interaction,
• cardiac failure,
• chest pain,
•  myocardial infarction,
• hypertension,
• involuntary movements, and
• rhabdomyolysis.

Cephalosporin Class Adverse Events

The following adverse events and altered laboratory tests have been reported for cephalosporinclass antibiotics in general:

• Allergic reactions,
• anaphylaxis,
• Stevens-Johnson syndrome,
•  erythema multiforme,
•  toxic epidermal necrolysis,
•  renal dysfunction,
• toxic nephropathy,
• hepatic dysfunction including
  • cholestasis,
  • aplastic anemia,
  •  hemolytic anemia,
  • hemorrhage,
  • false-positive test for urinary glucose,
  • neutropenia,
  • pancytopenia, and
  • agranulocytosis.

Pseudomembranous colitis symptoms may begin during or after antibiotic treatment.

Several cephalosporins have been implicated in triggering seizures, particularly in patients with renal impairment when the dosage was not reduced. If seizures associated with drug therapy occur, the drug should be discontinued. Anticonvulsant therapy can be given if clinically indicated.

Antacids (Aluminum- or Magnesium-containing)

• Concomitant administration of 300-mg cefdinir capsules with 30 mL Maalox TC suspension reduces the rate (Cmax) and extent (AUC) of absorption by approximately 40%. Time to reach Cmax is also prolonged by 1 hour.
• There are no significant effects on cefdinir pharmacokinetics if the antacid is administered 2 hours before or 2 hours after cefdinir.
• If antacids are required during OMNICEF therapy, OMNICEF should be taken at least 2 hours before or after the antacid.

Probenecid

• As with other β-lactam antibiotics, probenecid inhibits the renal excretion of cefdinir, resulting in an approximate doubling in AUC, a 54% increase in peak cefdinir plasma levels, and a 50% prolongation in the apparent elimination t½.

Iron Supplements and Foods Fortified With Iron

• Concomitant administration of cefdinir with a therapeutic iron supplement containing 60 mg of elemental iron (as FeSO4) or vitamins supplemented with 10 mg of elemental iron reduced extent of absorption by 80% and 31%, respectively.
• If iron supplements are required during OMNICEF therapy, OMNICEF should be taken at least 2 hours before or after the supplement.
• The effect of foods highly fortified with elemental iron (primarily iron-fortified breakfast cereals) on cefdinir absorption has not been studied.
• Concomitantly administered iron-fortified infant formula (2.2 mg elemental iron/6 oz) has no significant effect on cefdinir pharmacokinetics. Therefore, OMNICEF for Oral Suspension can be administered with iron-fortified infant formula.
• There have been reports of reddish stools in patients receiving cefdinir. In many cases, patients were also receiving iron-containing products. The reddish color is due to the formation of a nonabsorbable complex between cefdinir or its breakdown products and iron in the gastrointestinal tract.

Drug/Laboratory Test Interactions

• A false-positive reaction for ketones in the urine may occur with tests using nitroprusside, but not with those using nitroferricyanide.
• The administration of cefdinir may result in a false-positive reaction for glucose in urine using Clinitest, Benedict's solution, or Fehling's solution.
• It is recommended that glucose tests based on enzymatic glucose oxidase reactions (such as Clinistix or Tes-Tape) be used.
• Cephalosporins are known to occasionally induce a positive direct Coombs' test.