ceftazidime/avibactam vs ceftolozane/tazobactam
Side-by-side comparison of ceftazidime/avibactam and ceftolozane/tazobactam Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Avycaz
Zerbaxa
Avycaz is a drug that combines two medicines, ceftazidime and avibactam. It fights certain bacterial infections.
Zerbaxa is a combination of two antibiotics, ceftolozane and tazobactam. It fights bacterial infections in your body.
Avycaz treats complicated infections in the stomach area and urinary tract. This includes kidney infections. It also treats pneumonia that you get while in the hospital or from using a ventilator. Avycaz should only be used to treat infections that are proven or very likely to be caused by bacteria that it can kill.
Zerbaxa treats complicated infections in the stomach area and urinary tract. This includes kidney infections. It also treats pneumonia that you get while in the hospital or from being on a ventilator. Zerbaxa should only be used to treat infections that are proven or strongly suspected to be caused by bacteria.
Ceftazidime kills bacteria by attacking their cell walls. Avibactam helps ceftazidime work better by blocking certain enzymes that bacteria use to resist antibiotics. This allows ceftazidime to effectively kill the bacteria.
Ceftolozane kills bacteria by stopping them from building cell walls. Tazobactam helps ceftolozane work better by blocking the bacteria's defense mechanisms. This allows ceftolozane to effectively kill the bacteria.
- • Diarrhea
- • Nausea
- • Vomiting
- • Rash
- • Irritation at the injection site
- • Nausea
- • Diarrhea
- • Headache
- • Fever
- • Increased liver enzymes
- Drug Ineffective 826
- Off Label Use 657
- Pyrexia 533
- Septic Shock 335
- Condition Aggravated 319
- Off Label Use 138
- Product Use In Unapproved Indication 126
- No Adverse Event 88
- Death 81
- Product Use Issue 67
Avycaz may cause a lower clinical response in adult patients with complicated intra-abdominal infections and kidney problems. Your kidney function should be checked daily. The dose of Avycaz may need to be adjusted if you have kidney problems. Avycaz can also cause severe allergic reactions and Clostridium difficile-associated diarrhea (CDAD). Seizures and other nervous system problems can also occur, especially if you have kidney problems.
Zerbaxa may not work as well if your kidneys aren't working well. Your doctor should check your kidney function daily and adjust your dose if needed. Zerbaxa can also cause severe allergic reactions. Tell your doctor if you are allergic to any beta-lactam antibiotics. Diarrhea can occur with Zerbaxa, even months after you stop taking it. Tell your doctor right away if you have diarrhea.
It is not known if Avycaz will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. Ceftazidime passes into breast milk, but it is not known if avibactam does. Talk to your doctor about the best way to feed your baby if you take Avycaz.
It is not known if Zerbaxa will harm an unborn baby. Talk to your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
How to Read This ceftazidime/avibactam vs ceftolozane/tazobactam Comparison
ceftazidime/avibactam is classified in the Cephalosporin / Beta-Lactamase Inhibitor drug class, while ceftolozane/tazobactam sits within the Cephalosporin / Beta-Lactamase Inhibitor class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, ceftazidime/avibactam has 2,670 submissions while ceftolozane/tazobactam has 500. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between ceftazidime/avibactam and ceftolozane/tazobactam — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.