Is Zosyn (piperacillin/tazobactam) contraindicated in pregnant women?

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Last updated: June 9, 2025View editorial policy

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From the Guidelines

Zosyn (piperacillin/tazobactam) is not contraindicated in pregnant women and can be used when clinically indicated during pregnancy. According to the most recent evidence from the European Respiratory Journal in 2020 1, piperacillin/tazobactam is classified as compatible during pregnancy, with no teratogenic effects in animal studies and no cases of congenital defects reported in humans. The study notes that all penicillins, including piperacillin/tazobactam, are considered low risk in pregnancy.

Key points to consider when using Zosyn in pregnant women include:

  • The medication crosses the placenta, but there is no evidence of adverse fetal effects when used during pregnancy 1.
  • The standard adult dosing of Zosyn remains the same during pregnancy, with adjustments made for renal function as needed.
  • Healthcare providers should select antibiotics based on the suspected pathogens, local resistance patterns, and the severity of infection.
  • Zosyn is a broad-spectrum antibiotic effective against many gram-positive, gram-negative, and anaerobic bacteria, including many resistant strains.

Overall, the benefit of treating serious infections in pregnant women with Zosyn typically outweighs the theoretical risks, and it can be a valuable treatment option when clinically indicated 1.

From the FDA Drug Label

  1. 1 Pregnancy Risk Summary Piperacillin and tazobactam cross the placenta in humans. However, there are insufficient data with piperacillin and/or tazobactam in pregnant women to inform a drug-associated risk for major birth defects and miscarriage

Zosyn (piperacillin/tazobactam) is not explicitly contraindicated in pregnant women. However, there are insufficient data to inform a drug-associated risk for major birth defects and miscarriage.

  • The drug label recommends considering the benefits and risks of using piperacillin and tazobactam during pregnancy, but it does not provide a clear contraindication.
  • Fetotoxicity and maternal toxicity were observed in animal studies, but the clinical significance of these findings is unclear.
  • The decision to use Zosyn in pregnant women should be made on a case-by-case basis, taking into account the potential benefits and risks 2.

From the Research

Zosyn Contraindications in Pregnant Women

  • Zosyn, also known as piperacillin/tazobactam, is not strictly contraindicated in pregnant women, but its use should be approached with caution 3, 4.
  • The FDA categorizes piperacillin/tazobactam as a category B drug, indicating that it is moderately safe for use during pregnancy, but it should only be used when the benefits outweigh the risks 3.
  • Studies have shown that piperacillin/tazobactam can cross the placenta, but the risk of adverse effects on the fetus is considered low 4.
  • However, there have been reports of adverse reactions, such as bone marrow suppression, in pregnant women taking piperacillin/tazobactam 3.
  • The pharmacokinetics of piperacillin/tazobactam may be altered during pregnancy, which could affect the efficacy and safety of the drug 4.

Safety and Efficacy

  • Piperacillin/tazobactam has been shown to be effective in treating various infections, including those caused by beta-lactamase-producing bacteria 5, 6.
  • The drug is generally well-tolerated, but common adverse effects include gastrointestinal symptoms and skin reactions 5, 6.
  • In pregnant women, piperacillin/tazobactam may be used to treat infections such as post-cesarean endometritis, but its efficacy and safety should be carefully monitored 7.

Key Considerations

  • Pregnant women should only take piperacillin/tazobactam under the guidance of a healthcare provider, who can weigh the benefits and risks of treatment 3, 4.
  • Close monitoring of the patient's condition and the fetus's well-being is essential when using piperacillin/tazobactam during pregnancy 3, 4.
  • Alternative treatments may be considered if the risks associated with piperacillin/tazobactam are deemed too high 7.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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