FDA-filed SPL labeling · retrieved through openFDA

Ampicillin / Sulbactam

Ampicillin/sulbactam is a combination antibiotic injection used to treat skin and skin structure infections, intra-abdominal infections, and gynecological infections caused by susceptible bacteria.

Brand name Unasyn
Drug classes ⓘ Penicillin-class Antibacterial
Rx Form 1 Routes Intramuscular; Intravenous · Intravenous · Intramuscular, Intravenous
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 26 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

At a glance
Linked label effectiveJul 10, 2026
Clinical labels in scope ⓘ26
AvailabilityRx
Earliest approval/marketing year ⓘ1991
FDA-listed product records ⓘ137
Boxed warningNone found in compared labels
How we combine label and product data →
✓No current FDA shortage listed · checked Sep 23, 2026
⭐ Ampicillin / Sulbactam at a glance The quick version — the full detail is in the Patient Information Guide below.
💊
HelloPharmacist Editorial Team Bottom Line
Ampicillin/sulbactam is a broad-spectrum antibiotic combination given by IV or IM injection to treat skin, abdominal, and gynecological bacterial infections, including those caused by drug-resistant bacteria. It should only be used for proven or strongly suspected bacterial infections to help prevent antibiotic resistance. Serious allergic reactions and severe skin reactions are the most important risks to know about.
How we write & review this content — our editorial policy →

📖 Ampicillin / Sulbactam: Patient Information Guide

A plain-language walkthrough of Ampicillin / Sulbactam — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.

🎯What it's used for▾

Ampicillin/sulbactam injection is approved to treat bacterial infections in three main categories:

  • Skin and skin structure infections — including infections caused by resistant strains of bacteria such as Staphylococcus aureus, E. coli, Klebsiella, Proteus mirabilis, Bacteroides fragilis, Enterobacter, and Acinetobacter
  • Intra-abdominal infections — infections inside the abdomen caused by resistant strains including E. coli, Klebsiella, Bacteroides, and Enterobacter
  • Gynecological infections — caused by resistant strains of E. coli and Bacteroides

Unasyn is indicated for all three of these infection categories in adults and pediatric patients. Because the combination contains ampicillin, it also covers bacteria that are already susceptible to ampicillin alone, so mixed infections often don't need an extra antibiotic added.

⚙️How it works▾

Ampicillin kills bacteria by stopping them from building their cell walls — a critical structure bacteria need to survive and multiply. Sulbactam is a beta-lactamase inhibitor, meaning it blocks the enzymes (beta-lactamases) that some resistant bacteria produce to destroy ampicillin before it can do its job. By protecting ampicillin from these enzymes, sulbactam extends the range of bacteria that the combination can fight.

Sulbactam itself has very little direct antibiotic activity against most bacteria (with the exception of Neisseriaceae). Its value lies in shielding ampicillin so the pair can tackle bacteria that would otherwise be resistant to ampicillin and other similar antibiotics (beta-lactams).

💊How it's taken▾

Ampicillin/sulbactam is given only by injection — into a vein (IV) or into a muscle (IM) — in a hospital or clinical setting. It is typically administered every six hours. IV doses can be given as a slow injection over at least 10–15 minutes or as a diluted infusion over 15–30 minutes.

  • Adults may receive it by either the IV or IM route
  • Pediatric patients aged 1 year and older receive it by IV infusion; the IM route has not been established as safe or effective for children
  • Children weighing 40 kg or more are generally dosed on adult recommendations

Always follow your care team's instructions — they will determine the right schedule and duration based on your infection and kidney function.

🤒Side effects — in detail▾

Ampicillin/sulbactam is generally well tolerated, but some side effects can occur:

  • Pain at the IM or IV injection site (most common local reaction)
  • Phlebitis or thrombophlebitis (irritation or inflammation of the vein)
  • Diarrhea
  • Skin rash
  • Nausea, vomiting, or itching
  • Headache, fatigue, or malaise
  • Candidiasis (yeast overgrowth)

More serious reactions — including severe allergic responses, dangerous skin reactions like Stevens-Johnson syndrome or toxic epidermal necrolysis, liver toxicity, and C. difficile-associated diarrhea — require immediate medical attention. Tell your care team right away if you notice worsening rash, jaundice (yellowing of the skin or eyes), or severe diarrhea.

⚠️Warnings & precautions▾
  • Severe allergic reactions (anaphylaxis): Rare but potentially fatal. Risk is higher if you have a prior penicillin or cephalosporin allergy. Emergency treatment is needed immediately if this occurs.
  • Severe skin reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis (TEN), DRESS, and other serious skin conditions have been reported. Stop the medication if a rash worsens or spreads.
  • C. difficile-associated diarrhea (CDAD): Antibiotic use can allow C. difficile bacteria to overgrow in the gut, causing anything from mild diarrhea to life-threatening colitis. This can happen even weeks after finishing the antibiotic.
  • Liver toxicity (hepatotoxicity): Hepatitis and cholestatic jaundice have been reported, occasionally with fatal outcomes. Liver function should be monitored in patients with liver problems.
  • Seizures (convulsions): High levels of the drug in the fluid around the brain and spinal cord can cause neurological reactions, including seizures.
🔀What it interacts with▾

A few drugs can interact with ampicillin/sulbactam in clinically meaningful ways:

  • Probenecid: Slows kidney clearance of both ampicillin and sulbactam, leading to higher and longer-lasting drug levels in the blood.
  • Allopurinol: Significantly raises the likelihood of developing a skin rash when taken at the same time as ampicillin.
  • Aminoglycoside antibiotics (e.g., gentamicin, tobramycin): Must never be mixed together with ampicillin/sulbactam in the same IV bag or syringe — ampicillin can chemically inactivate aminoglycosides in solution.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

📋Before taking it▾
  • Tell your doctor if you have ever had a serious allergic reaction — especially anaphylaxis or Stevens-Johnson syndrome — to a penicillin, cephalosporin, or any other beta-lactam antibiotic
  • Tell your doctor if you have previously developed jaundice or liver problems linked to ampicillin/sulbactam — this is a contraindication and means you should not receive this drug
  • Tell your doctor if you have kidney problems; dosing frequency may need to be reduced
  • Tell your doctor if you have liver disease; liver function may need to be monitored during treatment
  • Tell your doctor if you are pregnant or breastfeeding
  • Not for use in children under 1 year of age (safety and effectiveness not established)
  • The IM route is not established as safe or effective for pediatric patients
🚑If you take too much▾

Taking too much ampicillin/sulbactam can lead to high levels of the drug in the fluid surrounding the brain and spinal cord, which may trigger neurological side effects including seizures (convulsions). If an overdose occurs, hemodialysis (a blood-filtering procedure) may help remove both ampicillin and sulbactam from the body. Seek emergency medical care immediately.

📡Pharmacodynamics — effects in the body▾

Ampicillin is a bactericidal antibiotic — it actively kills bacteria rather than just slowing their growth. It does this by interfering with the construction of bacterial cell walls during the stage when bacteria are actively multiplying. Sulbactam itself has very limited ability to kill bacteria on its own, but it irreversibly blocks beta-lactamase enzymes, which are the main tool many resistant bacteria use to neutralize penicillin-type antibiotics.

🔬Pharmacokinetics — how your body processes it▾

When given by IV infusion, peak blood levels of both ampicillin and sulbactam are reached immediately after the infusion ends. After an IM injection, peak levels are lower and take longer to reach. Both drugs have a short half-life of approximately 1 hour in people with normal kidney function. About 75–85% of each drug is excreted unchanged through the urine within 8 hours, making kidney function a key factor in how the body clears the medication. Both drugs also penetrate into peritoneal fluid, blister fluid, intestinal tissue, and — in the presence of inflamed meninges — cerebrospinal fluid (the fluid around the brain and spinal cord).

📦How to store it▾

stored at 20° to 25°C (68° to 77°F) prior to reconstitution.

📄 Written from Ampicillin / Sulbactam’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →

🩺 Pharmacist Counseling Corner

Quick, plain-English answers to the questions patients ask most about Ampicillin / Sulbactam — the kind of thing our pharmacy team would talk through with you at the counter.

Why am I getting this as an injection instead of a pill? ▾
Ampicillin/sulbactam is only available as an injection — it's given directly into a vein or muscle, typically in a hospital or clinical setting. This route gets the medication into your bloodstream quickly and at the levels needed to fight the type of infection you have. There isn't an oral (by mouth) version of this combination.
How long will I need to be on this antibiotic? ▾
The length of treatment depends on your specific infection and how well you're responding. Your doctor and care team will determine the right duration for you. It's important to complete the full course they prescribe, even if you start feeling better — stopping early can allow the infection to come back or become harder to treat.
What side effects should I expect, and which ones are serious enough to call about? ▾
The most common side effects are pain or irritation at the injection site, diarrhea, and occasionally a rash. These are usually mild. However, you should get help right away if you develop signs of a severe allergic reaction — such as hives, swelling, or trouble breathing — or if a rash starts spreading or blistering. Also let your care team know right away if you have severe or persistent diarrhea, even after you finish the antibiotic, since this can sometimes signal a serious gut infection.
I'm allergic to penicillin. Can I still take this? ▾
This is a really important thing to tell your doctor before starting. Ampicillin/sulbactam is a penicillin-type antibiotic, so if you've had a serious allergic reaction to penicillins or similar antibiotics (like cephalosporins), you should not take this medication. Be specific with your doctor about what kind of reaction you had — they'll decide whether an alternative antibiotic is safer for you.
I take allopurinol for gout. Is that a problem? ▾
Yes — it's worth flagging with your doctor. Taking allopurinol at the same time as ampicillin significantly increases the chance of developing a skin rash. Your care team will weigh this and keep an eye out for any skin changes while you're being treated.
Is this safe if I'm pregnant or breastfeeding? ▾
Make sure your doctor knows you're pregnant or breastfeeding before starting this medication. Your doctor will factor that into their decision and discuss the risks and benefits with you. Don't stop or start any medication on your own — let your care team guide you.
Is Ampicillin / Sulbactam available over the counter? ▾
Ampicillin / Sulbactam is dispensed by prescription according to its FDA labeling, so it isn't sold over the counter. Your prescriber and pharmacist will determine if it's appropriate for you.
When was Ampicillin / Sulbactam first available? ▾
Ampicillin / Sulbactam has been available in the United States since at least 1991, based on FDA approval history (Drugs@FDA) and product marketing records.
Who makes Ampicillin / Sulbactam? ▾
Ampicillin / Sulbactam is supplied by 23 manufacturers listed in the FDA NDC Directory, including Eugia US LLC, Meitheal Pharmaceuticals Inc., WG Critical Care, LLC.

💬 Answers drafted from Ampicillin / Sulbactam’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →

🧰 Keep exploring

🌿Drug & Supplement CheckerAmpicillin / Sulbactam vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Ampicillin / Sulbactam NDCs & costs 🅰️Browse Drugs A–ZLook up any medication

💊 How Ampicillin / Sulbactam comes

Ampicillin / Sulbactam is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Injection

Into a muscle · Into a vein
Brands Unasyn
How this form is used
What it may be used for
  • Treats skin and skin structure infections caused by susceptible bacteria
  • Treats intra-abdominal infections caused by susceptible bacteria
  • Treats gynecological infections caused by susceptible bacteria
  • Unasyn is indicated for these same three infection categories in adults and pediatric patients
Important instructions
  • May be given by slow IV injection over at least 10–15 minutes, or as an IV infusion over 15–30 minutes diluted in a compatible fluid
  • May be given by deep IM injection in adults; the IM route has not been established as safe or effective in pediatric patients
  • Ampicillin Sodium and Sulbactam Sodium pharmacy bulk package is for IV infusion preparation only — not for IM use
  • Doses are typically given every six hours; your care team will determine the right schedule for you
Available strengths 18 strengths
100 mg/mL / 50 mg/mL AMPICILLIN SODIUM 1 g/1.5 g; SULBACTAM SODIUM 0.5 g/1.5 g 1 g / 0.5 g AMPICILLIN SODIUM 1 g/10 mL; SULBACTAM SODIUM 0.5 g/10 mL 1 g / 2 g 2 g / 1 g
Show 12 more strengths Show fewer strengths
AMPICILLIN SODIUM 2 g/3 g; SULBACTAM SODIUM 1 g/3 g AMPICILLIN SODIUM 2 g/20 mL; SULBACTAM SODIUM 1 g/20 mL 10 g / 5 g AMPICILLIN SODIUM 10 g/15 g; SULBACTAM SODIUM 5 g/15 g AMPICILLIN SODIUM 10 g/100 mL; SULBACTAM SODIUM 5 g/100 mL 1; 0.5 g/1.5 g; g/1.5 g 1; 0.5 g/10 mL; g/10 mL 1; 0.5 g/20 mL; g/20 mL 2; 1 g/3 g; g/3 g 2; 1 g/20 mL; g/20 mL 10; 5 g/100 mL; g/100 mL 250 mg/mL / 125 mg/mL
133 FDA-listed product records ⓘ

📊 Ampicillin / Sulbactam across the U.S. market

How Ampicillin / Sulbactam appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

1
Dose forms ⓘ
23
Manufacturers
3
Brand names
137
FDA-listed product records ⓘ
1991
First marketed ⓘ

Also listed with the FDA, not a patient dose form: Powder (4) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.

Eugia US LLC15%
Meitheal Pharmaceuticals Inc.13%
WG Critical Care, LLC10%
Hikma Pharmaceuticals USA Inc.9%
Roerig9%
Sagent Pharmaceuticals6%
Other makers37%

Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

📈 How widely Ampicillin / Sulbactam is used

A general measure of how commonly Ampicillin / Sulbactam is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.

Think of this as a proxy for how widely Ampicillin / Sulbactam is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.

26,484
Medicaid prescriptions filled (Q1–Q4 2025)
$1.6M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Ampicillin / Sulbactam prescribed? Of the 1,596 medications we measure, Ampicillin / Sulbactam ranks #758 by Medicaid prescriptions — more than 53% of them.

Where Ampicillin / Sulbactam ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #758 of 1,596
#753 Golimumab Injection 27,172 Rx #754 Metronidazole Injectio... 27,056 Rx #755 Emicizumab 27,047 Rx #756 Zolmitriptan 27,026 Rx #757 Abemaciclib 27,007 Rx #758 Ampicillin and Sulbact... 26,484 Rx #759 Ampicillin / Sulbactam 26,484 Rx #760 Zoledronic Acid Inject... 26,317 Rx #761 Zoledronic Acid 26,317 Rx #762 Dolutegravir / Rilpivi... 26,206 Rx #763 Succinylcholine 25,454 Rx

Utilization by Ampicillin / Sulbactam product

Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.

The 2000 mg / 1000 mg injection is the most-dispensed Ampicillin / Sulbactam product — about 90% of these Medicaid prescriptions.

ampicillin 2000 MG / sulbactam 1000 MG Injection Most dispensed

23,745 Medicaid prescriptions (Q1–Q4 2025) 90% of Ampicillin / Sulbactam prescriptions shown $1.4M gross reimbursement (before rebates) ≈ $60 per prescription (gross)

Summed across the 12 of 44 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1659598

ampicillin 100 MG/ML / sulbactam 50 MG/ML Injectable Solution

1,399 Medicaid prescriptions (Q1–Q4 2025) 5% of Ampicillin / Sulbactam prescriptions shown $114,875 gross reimbursement (before rebates) ≈ $82 per prescription (gross)

Summed across the 7 of 23 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 240984

ampicillin 1000 MG / sulbactam 500 MG Injection

1,340 Medicaid prescriptions (Q1–Q4 2025) 5% of Ampicillin / Sulbactam prescriptions shown $83,793 gross reimbursement (before rebates) ≈ $63 per prescription (gross)

Summed across the 5 of 40 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1659592

Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.

Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Ampicillin / Sulbactam, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 24 of 107 listed Ampicillin / Sulbactam NDCs with Medicaid activity.

🔍 Compare Ampicillin / Sulbactam products

A representative set of FDA-listed product records for Ampicillin / Sulbactam — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)

Showing 137 of 137 products — FDA National Drug Code Directory. See every product, package size and price: browse all 137 Ampicillin / Sulbactam NDCs →

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one exact multiple-ingredient concept (MIN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). A product with a different ingredient combination belongs on a different page.

Multiple ingredients (MIN) Ampicillin / Sulbactam RxCUI 1009148 2 dose forms · 3 strengths

Look up RxCUI 1009148 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

🏷️ Sold under these brand names

Unasyn

🏭 Manufacturers & labelers

Eugia US LLC 21 Meitheal Pharmaceuticals Inc. 18 WG Critical Care, LLC 14 Hikma Pharmaceuticals USA Inc. 13 Roerig 12 Sagent Pharmaceuticals 8 Hospira, Inc 6 Xellia Pharmaceuticals USA LLC 6 Piramal Critical Care Inc 6 Civica, Inc. 5 Armas Pharmaceuticals Inc. 5 Mylan Institutional LLC 4 NorthStar Rx, LLC 3 Onesource Specialty Pharma Limited 3 Avenacy, LLC 3 Methapharm, Inc. 2 Steriscience Specialties Private Limited 2 West-Ward Pharmaceuticals Corp. 1 ACS Dobfar S.p.A 1 Fresenius Kabi iPSUM S.r.l. 1 Aurobindo Pharma Limited 1 Medical Purchasing Solutions, LLC. 1 Eumedica Pharmaceuticals Industries Sociedad Limitada 1

RxNorm drug class

Ampicillin / Sulbactam belongs to the beta Lactamase Inhibitor class.

Pharmacologic class beta Lactamase Inhibitor
Drug family (ATC) Beta-lactamase inhibitors
How it works beta Lactamase Inhibitors

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

🔬 Where this comes from

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Jul 10, 2026
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Ampicillin / Sulbactam.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Ampicillin / Sulbactam after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
26
NDC products indexed
137
Distinct labelers/manufacturers represented
23
Linked representative label ⓘ
Roerig
Linked label effective
Jul 10, 2026
Composite sections available
18
Linked SPL Set ID
155c7ec0-5862-404f-b1d0-f278f8a8bbda
Linked SPL Document ID
04da40ca-b337-4cac-a8d7-8dc9d5301c23
Open the linked representative label on DailyMed ↗

How we combine label and product data

HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 26 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.

For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Roerig is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.

This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.