Prescription medication · Carbapenem Antibiotic Combination
imipenem/cilastatin
Also sold as Primaxin. Primaxin treats serious infections like lung infections and urinary tract infections.
Data updated 2026-05-15
- 630
- FDA reports
- 2
- InteractionsFew interactions
- In shortage
- FDA status
What the data shows
imipenem/cilastatin (Primaxin) is a prescription Carbapenem Antibiotic Combination, with 630 FDA adverse-event reports on file, with 2 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
imipenem/cilastatin (Primaxin) is a prescription Carbapenem Antibiotic Combination. Primaxin treats serious infections like lung infections and urinary tract infections.
Primaxin is a strong antibiotic medicine. It fights serious infections in your body caused by certain bacteria.
Verify with FDA → · CMS NADAC pricing →
Drug Shortage Alert
imipenem/cilastatin is currently listed as to be discontinued by the FDA. Affected manufacturer: Merck Sharp & Dohme Corp..
View all drug shortages →What it does
Primaxin treats serious infections like lung infections and urinary tract infections.
Common side effects
Phlebitis (vein irritation), Nausea, Diarrhea
Key warnings
Primaxin can cause serious allergic reactions.
The sections below are summarized in plain English from imipenem/cilastatin's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Primaxin has two medicines: imipenem and cilastatin. Imipenem kills bacteria by stopping them from building cell walls. Cilastatin helps imipenem work better by preventing its breakdown in your kidneys.
How to Take It
Primaxin is given into your vein through an IV. The usual dose for adults with good kidney function is either 500 mg every 6 hours, 1000 mg every 8 hours, or 1000 mg every 6 hours. The IV infusion of 500 mg should take 20 to 30 minutes. A 1000 mg IV infusion should take 40 to 60 minutes. If you feel sick to your stomach during the infusion, the nurse may slow down the rate.
This is a plain-language summary of imipenem/cilastatin's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Not enough studies have been done to know if Primaxin is safe during pregnancy. Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.
This is a plain-language summary of imipenem/cilastatin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
Since Primaxin is given in a hospital or clinic, you don't have to worry about missing a dose.
This is a plain-language summary of imipenem/cilastatin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Keep Primaxin dry powder below 77°F (25°C).
Side Effects (from patient reports)
Based on 630 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for imipenem/cilastatin, by number of reports
- Pyrexia
Pyrexia
87 reports
- Pathogen Resistance
Pathogen Resistance
80 reports
- Thrombocytopenia
Thrombocytopenia
67 reports
- Electrocardiogram Qt Prolonged
Electrocardiogram Qt Prolonged
63 reports
- Nausea
Nausea
62 reports
- Vomiting
Vomiting
61 reports
- Anaemia
Anaemia
56 reports
- Diarrhoea
Diarrhoea
52 reports
- Septic Shock
Septic Shock
52 reports
- Respiratory Failure
Respiratory Failure
50 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Serious Warnings
Primaxin can cause serious allergic reactions. Tell your doctor if you are allergic to any beta-lactam antibiotics like penicillins or cephalosporins. Primaxin can also cause seizures, especially if you have a brain problem or kidney problems. It can also cause severe diarrhea from C. difficile. Using Primaxin with valproic acid may cause seizures.
Known Drug Interactions
Probenecid: Concomitant administration of PRIMAXIN and probenecid results in increases in the plasma level and half-life of imipenem. 7.2 Probenecid Concomitant administration of PRIMAXIN and probenecid results in increases in the plasma level and half-life of imipenem. Therefore, it is not recommended that probenecid be given concomitantly with PRIMAXIN.
Mechanism: Probenecid keeps imipenem in your blood for a longer time and at higher levels than usual.
What to do: It is recommended that you do not take these two medications at the same time.
7 DRUG INTERACTIONS Ganciclovir: Generalized seizures have been reported in patients who received ganciclovir. 7.1 Ganciclovir Generalized seizures have been reported in patients who received ganciclovir and PRIMAXIN.
Mechanism: Using these two drugs at the same time can increase the chance of having a seizure.
What to do: This combination should generally be avoided, and you should tell your doctor immediately if you feel any unusual brain activity.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What should I tell my doctor before taking Primaxin?
Can Primaxin cause seizures?
What if I get diarrhea while taking Primaxin?
Can I take Primaxin if I am allergic to penicillin?
Does Primaxin interact with other medications?
How will I receive Primaxin?
What if I feel nauseous during the IV infusion?
Is Primaxin safe for children?
How long will I need to take Primaxin?
What if my symptoms get worse while taking Primaxin?
What are the common side effects of imipenem/cilastatin?
Does imipenem/cilastatin interact with other medications?
What drug class is imipenem/cilastatin?
Is imipenem/cilastatin safe during pregnancy?
Is imipenem/cilastatin currently in shortage?
Related Medications in Carbapenem Antibiotic Combination
Other drugs grouped near imipenem/cilastatin - same-class peers and common alternatives.
amikacin
Amikin
Amikacin is an antibiotic medicine.
Compare with imipenem/cilastatin →
amoxicillin
Amoxil
Amoxicillin and Clavulanate Potassium is a combination medicine used to fight bacterial infections.
Compare with imipenem/cilastatin →
amoxicillin/clavulanate
Augmentin
Augmentin is a combination of two medicines, amoxicillin and clavulanate.
Compare with imipenem/cilastatin →
ampicillin/sulbactam
Unasyn
Unasyn is a combination of two antibiotics that fights bacteria in your body.
Compare with imipenem/cilastatin →
azithromycin
Zithromax, Z-Pack
Azithromycin is an antibiotic that fights bacteria.
Compare with imipenem/cilastatin →
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What the FDA Data Shows for imipenem/cilastatin
The FDA label for imipenem/cilastatin (sold under brand names such as Primaxin) classifies it as a prescription-only medication in the Carbapenem Antibiotic Combination class. Primaxin treats serious infections like lung infections and urinary tract infections. Official labeling lists 15 commonly reported side effects, including Phlebitis (vein irritation), Nausea, Diarrhea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 630 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Shortage status: FDA Drug Shortages Database.
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: July 5, 2024
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages