Side Effects of Cefzil (cefprozil)

Cefzil (cefprozil) is a cephalosporin antibiotic effective against susceptible bacteria causing infections of the middle ear, tonsils (tonsillitis), throat (pharyngitis), larynx (laryngitis), bronchi (bronchitis), skin and soft tissues, and lungs (pneumonia). 

Cephalosporins stop or slow the growth of bacterial cells by preventing bacteria from forming the cell wall that surrounds each cell. The cell wall protects bacteria from the external environment and keeps the contents of the cell together. Without a cell wall, bacteria are not able to survive.

Common side effects of Cefzil include

• diarrhea or loose stools,
• nausea,
• abdominal pain,
• vomiting,
• rash, and
• headache.

Serious but rare side effects of Cefzil include

• abnormal liver tests,
• allergic reactions, and
• pseudomembranous colitis, a potentially serious bacterial infection of the colon. 

Drug interactions of Cefzil include probenecid, which may increase the blood concentration of Cefzil by decreasing excretion of Cefzil by the kidney. This interaction is sometimes used to enhance the effect of cephalosporins.

• Combining Cefzil with aminoglycosides (for example, tobramycin) produces additive bacterial killing effects but also may increase the risk of harmful effects to the kidney.
• Exenatide may delay or reduce the absorption of cephalosporins.
• Cephalosporins should be administered one hour before exenatide.
• Cefzil may cause false test results with some tests for sugar in the urine. 

There are no adequate studies of Cefzil in pregnant women. 

Small amounts of Cefzil are secreted in breast milk, but the effect on the infant is unknown. Consult your doctor before breastfeeding. 

Cefprozil is generally well tolerated. The most common side effects are:

• diarrhea or loose stools,
• nausea,
• abdominal pain,
• vomiting,
• rash, and
• headache.

Rare side effects include abnormal liver tests and allergic reactions. Like most antibiotics cefprozil may cause a condition called pseudomembranous colitis, a potentially serious bacterial infection of the colon. Persons with phenylketonuria should be advised that the suspension contains phenylalanine.

The adverse reactions to cefprozil are similar to those observed with other orally administered cephalosporins. Cefprozil was usually well tolerated in controlled clinical trials. Approximately 2% of patients discontinued cefprozil therapy due to adverse events.

The most common adverse effects observed in patients treated with cefprozil are:

Gastrointestinal

• Diarrhea (2.9%),
• nausea (3.5%),
• vomiting (1%), and
• abdominal pain (1%).

Hepatobiliary

• Elevations of AST (SGOT) (2%),
• ALT (SGPT) (2%),
• alkaline phosphatase (0.2%), and
• bilirubin values ( < 0.1%).

As with some penicillins and some other cephalosporin antibiotics, cholestatic jaundice has been reported rarely.

Hypersensitivity

• Rash (0.9%),
• urticaria (0.1%).

Such reactions have been reported more frequently in children than in adults. Signs and symptoms usually occur a few days after initiation of therapy and subside within a few days after cessation of therapy.

CNS

• Dizziness (1%),
• hyperactivity,
• headache,
• nervousness,
• insomnia,
• confusion, and
• somnolence have been reported rarely ( < 1%).

All were reversible.

Hematopoietic

• Decreased leukocyte count (0.2%),
• eosinophilia (2.3%).

Renal

• Elevated BUN (0.1%),
• serum creatinine (0.1%).

Other

• Diaper rash and superinfection (1.5%),
• genital pruritus and vaginitis (1.6%).

The following adverse events, regardless of established causal relationship to CEFZIL (cefprozil), have been rarely reported during postmarketing surveillance:

• anaphylaxis,
• angioedema,
• colitis (including pseudomembranous colitis),
• erythema multiforme,
• fever,
• serum-sickness like reactions,
• Stevens-Johnson syndrome, and
• thrombocytopenia.

Cephalosporin class paragraph

In addition to the adverse reactions listed above which have been observed in patients treated with cefprozil, the following adverse reactions and altered laboratory tests have been reported for cephalosporin-class antibiotics:

• Aplastic anemia,
• hemolytic anemia,
• hemorrhage,
• renal dysfunction,
• toxic epidermal necrolysis,
•  toxic nephropathy,
• prolonged prothrombin time,
• positive Coombs' test,
• elevated LDH,
• pancytopenia,
• neutropenia,
• agranulocytosis.

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.

• Nephrotoxicity has been reported following concomitant administration of aminoglycoside antibiotics and cephalosporin antibiotics. Concomitant administration of probenecid doubled the AUC for cefprozil.
• The bioavailability of the capsule formulation of cefprozil was not affected when administered 5 minutes following an antacid.

Drug/Laboratory Test Interactions

• Cephalosporin antibiotics may produce a false positive reaction for glucose in the urine with copper reduction tests (Benedict's or Fehling's solution or with Clinitest tablets), but not with enzyme-based tests for glycosuria (eg, Clinistix).
• A false negative reaction may occur in the ferricyanide test for blood glucose.
• The presence of cefprozil in the blood does not interfere with the assay of plasma or urine creatinine by the alkaline picrate method.