Cefprozil is an oral antibiotic used to treat mild to moderate bacterial infections of the ears, sinuses, throat, skin, and lungs. It belongs to a class of drugs called second-generation cephalosporins, which work by disrupting how bacteria build their protective cell walls, ultimately killing them. It’s taken by mouth as a tablet or liquid suspension, typically twice a day for 10 days.
Infections Cefprozil Treats
Cefprozil is approved to treat a specific set of bacterial infections. In the upper respiratory tract, it covers strep throat and tonsillitis, ear infections (otitis media), and acute sinusitis. For the lungs, it’s used when bronchitis develops a secondary bacterial infection or when chronic bronchitis flares up due to bacteria. It also treats uncomplicated skin infections like cellulitis or wound infections caused by staph or strep bacteria.
It is sometimes prescribed off-label for pneumonia, though this isn’t one of its formal approvals. In every case, cefprozil only works against bacteria. It will not help with viral illnesses like the common cold or flu.
How It Works Against Bacteria
Cefprozil is a beta-lactam antibiotic, the same broad family that includes penicillin. It interferes with the proteins bacteria need to assemble their cell walls. Without an intact wall, bacteria can’t survive or reproduce, so the infection clears. One advantage of cefprozil over older penicillin-type drugs is that it remains effective against certain bacteria that produce enzymes called beta-lactamases, which normally break down and inactivate penicillin. This makes it useful for ear and sinus infections caused by common resistant strains.
Typical Dosing for Adults and Children
For adults and teenagers, cefprozil is usually taken as 250 to 500 mg every 12 hours, depending on the infection. Bronchitis calls for 500 mg twice daily, while sinusitis may start at 250 mg twice daily. Strep throat and tonsillitis are often treated with a single 500 mg dose once a day. Most courses last 10 days.
Children ages 6 months to 12 years receive weight-based doses. For ear infections, the typical dose is 15 mg per kilogram of body weight every 12 hours. For sinusitis, it ranges from 7.5 to 15 mg per kilogram every 12 hours. For skin infections in children 2 and older, the daily dose is usually 20 mg per kilogram. A pediatrician will calculate the exact amount.
People with significant kidney impairment (creatinine clearance below 30 mL/min) typically need their dose cut in half, since the kidneys are the primary route the drug leaves the body. Liver problems do not require a dose change.
The Liquid Suspension
Cefprozil comes as a powder that a pharmacist mixes with water before dispensing. Once reconstituted, the liquid must be stored in the refrigerator between 36°F and 46°F. Any unused portion should be thrown away after 14 days, even if some is left. Before it’s mixed, the dry powder can be stored at room temperature.
Allergy Concerns With Penicillin
Because cefprozil and penicillin share a similar chemical backbone (the beta-lactam ring), there is some cross-reactivity for people with penicillin allergies. For first- and second-generation cephalosporins like cefprozil, the estimated cross-reaction rate is 1% to 8%. That’s higher than the rate for third-generation cephalosporins, which is below 1%.
If you’ve had a mild rash from penicillin in the past, your provider may still consider cefprozil after weighing the risks. But if you’ve ever experienced anaphylaxis, severe skin reactions like Stevens-Johnson syndrome, or other serious immune-mediated reactions to penicillin or any beta-lactam antibiotic, cefprozil should be avoided entirely. In those situations, an allergist can help identify safe alternatives.
Common Side Effects
Cefprozil is generally well tolerated. The most frequently reported side effects are gastrointestinal: nausea, diarrhea, vomiting, and abdominal pain. Some people develop a mild skin rash. These effects are usually mild enough that most people can finish the full course without stopping the medication.
Like all antibiotics, cefprozil can disrupt the normal bacteria in your gut, occasionally leading to yeast infections or, rarely, a more serious intestinal infection. If you develop watery or bloody diarrhea during or after treatment, that warrants prompt medical attention.
Use During Pregnancy and Breastfeeding
Very little cefprozil passes into breast milk. In a study measuring drug levels over 24 hours, the highest concentration found in milk was 3.36 micrograms per milliliter. Even at that peak level, an infant nursing on 800 mL of milk per day would be exposed to roughly 3 mg of the drug, which is about 0.3% of the mother’s dose. This is a very small amount, and cefprozil is generally considered compatible with breastfeeding. Your provider can help weigh the benefits and any individual risk factors during pregnancy, as data in that area is more limited.