Unasyn vs. Zosyn

Are Unasyn and Zosyn the Same Thing?

Unasyn (ampicillin sodium/sulbactam sodium) and Zosyn (piperacillin and tazobactam for injection) are combination antibiotics indicated to treat bacterial infections.

What Are Possible Side Effects of Unasyn?

Common side effects of Unasyn include:

  • fever,
  • sore throat,
  • headache,
  • rash,
  • diarrhea,
  • body aches,
  • nausea,
  • vomiting,
  • stomach pain,
  • bloating,
  • gas,
  • vaginal itching or discharge,
  • itching,
  • swollen/black/"hairy" tongue,
  • thrush (white patches inside your mouth or throat), or
  • pain, swelling, or irritation where the needle is placed.

What Are Possible Side Effects of Zosyn?

Common side effects of Zosyn include:

  • swelling,
  • redness,
  • pain,
  • soreness or
  • irritation;
  • dizziness,
  • agitation,
  • trouble sleeping (insomnia),
  • nausea,
  • vomiting,
  • stomach pain or upset,
  • diarrhea,
  • constipation,
  • headache,
  • runny nose,
  • anxiety,
  • skin rash or
  • itching, or
  • vaginal discharge or itching.

Tell your doctor if you have serious side effects of Zosyn including muscle cramps or spasms, swelling of the arms/legs/hands/feet, easy bruising or bleeding, chest pain, confusion, new signs of infection (such as fever, persistent sore throat), severe abdominal or stomach pain, slow/fast/irregular heartbeat, persistent nausea or vomiting, seizures, extreme tiredness, dark or cloudy urine, change in the amount of urine, yellowing eyes or skin, or serious skin reactions (rash, peeling, sores, or blisters).

What is Unasyn?

Unasyn (ampicillin sodium/sulbactam sodium) is a combination antibiotic indicated for the treatment of infections due to susceptible strains of microorganisms.

What is Zosyn?

Zosyn (piperacillin and tazobactam for injection) is a combination of two antibiotics used to treat many different infections caused by bacteria, such as urinary tract infections, bone and joint infections, severe vaginal infections, stomach infections, skin infections, and pneumonia. Zosyn is available in generic form.

What Drugs Interact With Unasyn?

Unasyn may interact with allopurinol, probenecid, or other antibiotics.

What Drugs Interact With Zosyn?

Zosyn may interact with probenecid, antibiotics, blood thinners, or any other medication used to prevent blood clots. Tell your doctor all medications you use.

How Should Unasyn Be Taken?

Unasyn is administered orally in the form of tablets.

How Should Zosyn Be Taken?

The usual total daily dose of Zosyn for adults is 3.375 g every six hours totaling 13.5 g (12.0 g piperacillin/1.5 g tazobactam).


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Pfizer. Unasyn Product Information.
Pfizer. Zosyn Product Information.

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