FDA-filed SPL labeling · retrieved through openFDA

Oxacillin Injection

Oxacillin Injection is a penicillin-type antibiotic used to treat serious bacterial infections caused by penicillinase-producing staphylococci.

Brand name Bactocill
Drug classes Penicillin-class Antibacterial
Rx Form 1 Routes Intramuscular; Intravenous · Intramuscular, Intravenous · 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 9 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 effectiveApr 2, 2026
Clinical labels in scope 9
AvailabilityRx
Earliest approval/marketing year 1971
FDA-listed product records 40
Boxed warningNone found in compared labels
How we combine label and product data →
No current FDA shortage listed · checked Sep 15, 2026
Oxacillin Injection at a glance The quick version — the full detail is in the Patient Information Guide below.
💊
HelloPharmacist Editorial Team Bottom Line
Oxacillin Injection is a targeted antibiotic for serious staph infections that have developed resistance to standard penicillin. It must be given by a healthcare provider in a clinical setting and requires monitoring of kidney, liver, and blood counts during treatment. If you experience any signs of a severe allergic reaction or severe diarrhea at any point during or after treatment, seek medical care immediately.

📖 Oxacillin Injection: Patient Information Guide

A plain-language walkthrough of Oxacillin Injection — 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

Oxacillin Injection is a penicillin-type antibiotic used specifically against staph bacteria that resist ordinary penicillin.

  • Treats infections caused by penicillinase-producing staphylococci — staph strains that produce an enzyme to break down standard penicillin
  • Can be used to start treatment when a resistant staph infection is strongly suspected, even before lab confirmation
  • Treats serious staph infections such as endocarditis (infection of the heart valves) and osteomyelitis (bone infection), which may need longer courses
  • Should not be used for infections caused by organisms that are still susceptible to regular penicillin G, or for infections caused by non-staph organisms
⚙️How it works

Oxacillin kills bacteria by interfering with their ability to build and maintain their cell walls. Without a strong cell wall, bacteria fall apart and die. This action happens while bacteria are actively growing and dividing, so the drug is most effective against rapidly multiplying staph bacteria. Because it is structurally resistant to the penicillinase enzyme that staph produce, it stays active where regular penicillin would be destroyed.

Bacteria can still develop resistance to oxacillin through other mechanisms — such as changing the target the drug binds to, or preventing the drug from getting inside the cell. If a staph strain is resistant to oxacillin, it is also considered resistant to all other beta-lactam antibiotics (a large class that includes most penicillins and cephalosporins), with the exception of some newer agents designed specifically for resistant strains.

💊How it's taken

Oxacillin Injection is given by a healthcare provider either directly into a vein (IV) or into a muscle (IM). It is typically administered multiple times throughout the day, every four to six hours, with the exact schedule and duration determined by your care team based on the type and severity of infection.

  • For severe infections, treatment generally continues for at least 14 days
  • Treatment should continue for at least 48 hours after you are fever-free, symptom-free, and cultures are negative
  • Conditions like endocarditis or osteomyelitis may require an even longer course

Follow your prescriber's instructions precisely — completing the full course is important even if you feel better early.

🤒Side effects — in detail

Like all antibiotics, oxacillin can cause side effects ranging from mild to serious.

  • Allergic reactions — hives, itching, rash, or fever
  • Nausea, vomiting, or diarrhea
  • Black or hairy tongue
  • Vein irritation (thrombophlebitis) with IV use, especially in older adults
  • Elevated liver enzymes (detected on blood tests)
  • Decreased white blood cell count — agranulocytosis or neutropenia
  • Kidney inflammation (interstitial nephritis) — may show as blood or protein in the urine
  • Nervous system effects such as twitching or neurotoxicity with high IV doses, especially in patients with kidney problems

Seek emergency care immediately if you develop difficulty breathing, throat tightening, or sudden collapse — these are signs of a life-threatening allergic reaction. Also contact your doctor right away for severe or persistent diarrhea, which may indicate a serious C. difficile bowel infection.

⚠️Warnings & precautions
  • Severe allergic reactions (anaphylaxis): Oxacillin and all penicillins can cause rare but potentially fatal allergic reactions, including cardiovascular collapse. Anyone with a known penicillin allergy must not receive oxacillin. People with cephalosporin allergies may also be at risk. Emergency resuscitation equipment should be available during administration.
  • C. difficile colitis: Antibiotic use can disrupt normal gut bacteria, allowing C. difficile to overgrow and cause serious colon inflammation. Symptoms — including severe diarrhea — can appear during treatment or up to two months after finishing the antibiotic. Prompt medical evaluation is essential.
  • Kidney and liver monitoring: Prolonged use of oxacillin can affect kidney and liver function. Regular blood and urine tests are recommended during treatment, and dose adjustments may be needed if problems develop.
  • Blood cell monitoring: Oxacillin has been associated with low white blood cell counts (neutropenia, agranulocytosis) and bone marrow suppression. Blood counts should be checked before and during therapy.
🔀What it interacts with

Oxacillin has a small but important list of drug interactions to be aware of.

  • Tetracycline antibiotics: These work in a different way than oxacillin (they slow bacterial growth rather than killing bacteria outright). Using both together can reduce oxacillin's effectiveness — this combination should be avoided.
  • Probenecid (a gout medication): This drug blocks the kidneys from clearing oxacillin, which raises oxacillin blood levels and keeps them elevated longer. This interaction is generally avoided unless very high oxacillin levels are specifically needed for a difficult infection.

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 any allergic reaction to a penicillin or cephalosporin antibiotic — oxacillin cannot be used if you have had a serious penicillin allergy
  • Tell your doctor if you have kidney disease — dose adjustments and closer monitoring may be needed to prevent toxic effects
  • Tell your doctor if you have liver disease — oxacillin can affect liver function and requires periodic liver enzyme monitoring
  • Tell your doctor if you are allergic to corn or corn products, as some oxacillin solutions contain dextrose (a corn-derived sugar)
  • Tell your doctor about all medications you take, especially tetracyclines or probenecid
  • Older adults receiving IV oxacillin should be monitored for vein irritation (thrombophlebitis) at the injection site
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding so the risks and benefits can be discussed
🚑If you take too much

If too much oxacillin is given, symptoms are generally those described under side effects — particularly effects on the nervous system, kidneys, and gastrointestinal tract. If an overdose is suspected, the medication should be stopped right away, and supportive medical care should be provided to manage symptoms. Contact a poison control center or emergency services immediately if an overdose is suspected.

📡Pharmacodynamics — effects in the body

Oxacillin kills susceptible staphylococcal bacteria by blocking the construction of their cell walls. It is active specifically when bacteria are multiplying — it does not have activity against resting or dormant bacteria. Because it is structurally designed to resist the penicillinase enzyme, it retains this killing activity against staph strains that would destroy ordinary penicillin. Its bactericidal (bacteria-killing, rather than just bacteria-slowing) action is why it is preferred for serious staph infections.

🔬Pharmacokinetics — how your body processes it

When given intravenously (into a vein), oxacillin reaches its peak level in the blood within about 5 minutes of the injection finishing. When given intramuscularly (into a muscle), peak levels are reached in about 30 minutes. The drug is cleared quickly — its half-life (the time for blood levels to drop by half) is roughly 30 minutes. Oxacillin is eliminated primarily through the kidneys, but the liver also plays a role in processing and excreting it through bile. It binds strongly to proteins in the blood (about 94%), which affects how it distributes throughout the body — it does not reach significant levels in the fluid around the brain or spine under normal dosing.

📦How to store it

Store dry powder at 20° to 25°C (68° to 77°F) .

📄 Written from Oxacillin Injection’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 →

56

Supplements & herbs that interact with Oxacillin Injection

56 supplements and herbal products have documented interactions with Oxacillin Injection in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.

Severity mix
  • Major · 3
  • Moderate · 42
  • Minor · 11
Every supplement checked against Oxacillin Injection — ranked by severity The full interaction hub: 3 major · 42 moderate · 11 minor · every one linked to its full report. Check Oxacillin Injection against your exact supplements

Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.

7

Nutrient depletion considerations

Oxacillin Injection has been associated with lower levels of 7 nutrients in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.

Evidence & significance mix
  • Higher significance · 6
  • Moderate · 1
See the full Oxacillin Injection nutrient depletion report

Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.

🩺 Pharmacist Counseling Corner

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

Why am I getting oxacillin instead of a regular penicillin?
Oxacillin is specifically designed to fight staph bacteria that have learned to break down standard penicillin. The staph strain causing your infection produces an enzyme called penicillinase, which destroys ordinary penicillin before it can work. Oxacillin is built to withstand that enzyme, so it can still do its job and clear the infection.
How long will I need to be on this antibiotic?
That depends on how serious your infection is and how well your body responds. Mild to moderate infections are often treated for at least two weeks, while serious infections like endocarditis (a heart valve infection) or osteomyelitis (a bone infection) may need a longer course. Your care team will keep checking your symptoms and lab results to decide when it's safe to stop — don't stop early even if you feel better, because that can let the infection come back.
What side effects should I watch out for while on oxacillin?
The most important thing to watch for is a severe allergic reaction — signs include sudden difficulty breathing, throat tightening, severe hives, or feeling faint. Get emergency help immediately if that happens. More common, milder things include rash, nausea, vomiting, or diarrhea. Also let your doctor know right away if you get significant diarrhea — even after you've finished the antibiotic — because it can sometimes signal a serious gut infection called C. difficile colitis.
I've heard penicillin can cause allergic reactions — how will my care team keep me safe?
Before starting oxacillin, your care team should review your full allergy history. If you've never had a reaction to penicillin or cephalosporin antibiotics, your risk of a severe reaction is low, but not zero. That's why oxacillin is always given in a clinical setting where emergency medications and equipment are on hand. If you've had a serious penicillin allergy in the past, oxacillin cannot safely be used — make sure your team knows your full allergy history.
Are there any medications I need to avoid while taking oxacillin?
Two are worth mentioning. First, tetracycline antibiotics (like doxycycline) can actually interfere with how well oxacillin kills bacteria, so those two shouldn't be used together. Second, a gout medication called probenecid slows down how fast your kidneys clear oxacillin from your body, which raises blood levels higher than intended. Make sure your care team has a full list of everything you take so they can catch any potential problems.
Why do I need blood and urine tests while on oxacillin?
Oxacillin can occasionally affect the kidneys, liver, and blood cell counts — especially with longer courses of treatment. Regular lab checks allow your care team to catch any early changes and adjust your treatment before a small problem becomes a bigger one. Think of it as a safety net running alongside your antibiotic course.
Is Oxacillin Injection available over the counter?
Oxacillin Injection 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 Oxacillin Injection first available?
Oxacillin Injection has been available in the United States since at least 1971, based on FDA approval history (Drugs@FDA) and product marketing records.
Who makes Oxacillin Injection?
Oxacillin Injection is supplied by 10 manufacturers listed in the FDA NDC Directory, including Wockhardt USA LLC., Baxter Healthcare Corporation, Eugia US LLC.

💬 Answers drafted from Oxacillin Injection’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

💊 How Oxacillin Injection comes

Oxacillin Injection 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
How this form is used
What it may be used for
  • OXACILLIN Injection is used to treat infections caused by penicillinase-producing staphylococci confirmed or strongly suspected to be susceptible to the drug
  • OXACILLIN Injection may be started before lab results are available when a resistant staph infection is strongly suspected
  • OXACILLIN Injection is used for serious infections including endocarditis and osteomyelitis, which may require longer courses of treatment
Important instructions
  • OXACILLIN Injection is given intravenously (into a vein) or intramuscularly (into a muscle) by a trained healthcare provider
  • OXACILLIN Injection is typically given in divided doses throughout the day; the exact schedule depends on the severity of the infection and your overall condition
  • OXACILLIN Injection should not be mixed in the same IV line with other medications — any additional drugs should be given separately
  • Treatment with OXACILLIN Injection should continue for at least 48 hours after symptoms resolve and cultures are negative; severe infections typically require at least 14 days
Available strengths 8 strengths
Show 2 more strengths Show fewer strengths
40 FDA-listed product records

📊 Oxacillin Injection across the U.S. market

How Oxacillin Injection 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
10
Manufacturers
1
Brand names
40
FDA-listed product records
1971
First marketed
Wockhardt USA LLC.23%
Baxter Healthcare Corporation18%
Eugia US LLC15%
Sagent Pharmaceuticals13%
Armas Pharmaceuticals Inc.8%
AuroMedics Pharma LLC8%
Other makers18%

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

📈 How widely Oxacillin Injection is used

A general measure of how commonly Oxacillin Injection 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 Oxacillin Injection 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.

1,714
Medicaid prescriptions filled (Q1–Q4 2025)
$534,438 gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Oxacillin Injection prescribed? Of the 1,594 medications we measure, Oxacillin Injection ranks #1,211 by Medicaid prescriptions — more than 24% of them.

Where Oxacillin Injection ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5

Utilization by Oxacillin Injection 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 100 mg/mL injectable solution is the most-dispensed Oxacillin Injection product — about 56% of these Medicaid prescriptions.

oxacillin 100 MG/ML Injectable Solution Most dispensed

963 Medicaid prescriptions (Q1–Q4 2025) 56% of Oxacillin Injection prescriptions shown $391,449 gross reimbursement (before rebates) ≈ $406 per prescription (gross)

Summed across the 2 of 15 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 312127

oxacillin 2000 MG Injection

595 Medicaid prescriptions (Q1–Q4 2025) 35% of Oxacillin Injection prescriptions shown $136,981 gross reimbursement (before rebates) ≈ $230 per prescription (gross)

Summed across the 4 of 15 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1743549

oxacillin 1000 MG Injection

144 Medicaid prescriptions (Q1–Q4 2025) 8% of Oxacillin Injection prescriptions shown $609 gross reimbursement (before rebates) ≈ $4.23 per prescription (gross)

Summed across the 1 of 12 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1743547

50 ML oxacillin 40 MG/ML Injection

12 Medicaid prescriptions (Q1–Q4 2025) <1% of Oxacillin Injection prescriptions shown $5,399 gross reimbursement (before rebates) ≈ $450 per prescription (gross)

Summed across the 1 of 1 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 240637

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 Oxacillin Injection, 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 8 of 43 listed Oxacillin Injection NDCs with Medicaid activity.

🔍 Compare Oxacillin Injection products

A representative set of FDA-listed product records for Oxacillin Injection — 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 40 of 40 products — FDA National Drug Code Directory. See every product, package size and price: browse all 40 Oxacillin Injection NDCs →

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Oxacillin Injection RxCUI 7773 4 dose forms · 8 strengths
  1. Dose form (SCDF) Injectable Solution RxCUI 376698 In current FDA listings
    Clinical drug / strength (SCD) 100 MG/ML RxCUI 312127
  2. Dose form (SCDF) Oral Capsule RxCUI 373165 No current FDA listing
    Clinical drug / strength (SCD) 250 MG RxCUI 198054 500 MG RxCUI 198055
  3. Dose form (SCDF) Oral Suspension RxCUI 393313 No current FDA listing
    Clinical drug / strength (SCD) 50 MG/ML RxCUI 312129

Look up RxCUI 7773 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

Bactocill

🏭 Manufacturers & labelers

Wockhardt USA LLC. 9 Baxter Healthcare Corporation 7 Eugia US LLC 6 Sagent Pharmaceuticals 5 Armas Pharmaceuticals Inc. 3 AuroMedics Pharma LLC 3 Fresenius Kabi USA, LLC 3 Onesource Specialty Pharma Limited 2 Piramal Critical Care Inc 1 Steriscience Specialties Private Limited 1

RxNorm drug class

Oxacillin Injection belongs to the Penicillin-class Antibacterial class.

Pharmacologic class Penicillin-class Antibacterial
Drug family (ATC) Beta-lactamase resistant penicillins

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 Apr 2, 2026
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Oxacillin Injection.
📈
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 Oxacillin Injection after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
9
NDC products indexed
40
Distinct labelers/manufacturers represented
10
Linked representative label
Baxter Healthcare Corporation
Linked label effective
Apr 2, 2026
Composite sections available
17
Linked SPL Set ID
d893e45b-7f18-4c67-b10c-1e2e52a6b3ef
Linked SPL Document ID
bc7ecac9-8fe4-4bf9-8a0b-addce4d5e5bb
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 9 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.

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. Baxter Healthcare Corporation 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.