FDA-filed SPL labeling · retrieved through openFDA

Sulfamethoxazole / Trimethoprim

Sulfamethoxazole/trimethoprim (SMX-TMP) is a combination antibiotic given by IV infusion to treat serious bacterial infections and a specific type of pneumonia.

Brand names SulfatrimSulfamethoxazole and Trimethoprim DSBactrimBactrim DSSulfamethox-TMP DS
Drug classes ⓘ Sulfonamide Antimicrobial
Rx Forms 3 Routes Oral · 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 101 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 effectiveDec 30, 2024
Clinical labels in scope ⓘ101
AvailabilityRx
Earliest approval/marketing year ⓘ1983
FDA-listed product records ⓘ272
Boxed warningNone found in compared labels
How we combine label and product data →
✓No current FDA shortage listed · checked Sep 23, 2026
⭐ Sulfamethoxazole / Trimethoprim at a glance The quick version — the full detail is in the Patient Information Guide below.
💊
HelloPharmacist Editorial Team Bottom Line
Sulfamethoxazole/trimethoprim IV is a powerful two-drug antibiotic combination reserved for serious infections when oral treatment isn't possible. It works well but comes with important risks — especially serious skin, blood, and lung reactions — so your care team will watch you closely. Always report any new rash, breathing changes, or unusual bruising right away.
How we write & review this content — our editorial policy →

📖 Sulfamethoxazole / Trimethoprim: Patient Information Guide

A plain-language walkthrough of Sulfamethoxazole / Trimethoprim — 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▾

This IV antibiotic combination is used to treat serious infections in adults and children two months and older, specifically:

  • Pneumocystis jirovecii pneumonia (PCP) — a serious fungal lung infection, especially in people with weakened immune systems
  • Shigellosis — a bacterial intestinal infection causing severe, sometimes bloody diarrhea
  • Severe or complicated urinary tract infections (UTIs) — caused by specific bacteria when oral antibiotics won't work or can't be taken
⚙️How it works▾

The two drugs in this combination — sulfamethoxazole and trimethoprim — work as a team. They block two separate steps in the same process that bacteria use to make folate, a nutrient bacteria need to grow. Blocking both steps at once is far more effective than blocking just one, because bacteria can't easily work around both roadblocks at the same time. Without folate, the bacteria can't multiply and eventually die.

Because this drug targets a pathway specific to bacteria (and certain parasites like Pneumocystis), it can be used to treat a range of infections. However, it only works against organisms that are actually susceptible to it — your doctor should confirm this with lab testing when possible.

💊How it's taken▾

This medication is given only as an intravenous (IV) infusion — directly into a vein — by a healthcare professional. It must be infused slowly over 60 to 90 minutes each time; a rapid injection is not safe. It cannot be given as a muscle injection.

  • The number of doses per day and the length of treatment vary by infection type — your care team will set the right schedule
  • Patients with reduced kidney function require a lower dose or may not be able to use this drug at all
  • Do not mix this IV solution with other medications or solutions
🤒Side effects — in detail▾

The most common side effects are stomach-related and skin-related. Here's what to watch for:

  • Nausea, vomiting, or loss of appetite
  • Skin rash or hives
  • Pain or irritation at the IV site
  • Low blood sugar (hypoglycemia) — shakiness, sweating, confusion
  • Changes in blood electrolytes (salts your body needs to function)

Serious reactions — including life-threatening skin blistering, severe liver damage, dangerous drops in blood cell counts, and severe lung reactions — have been reported. Stop the drug and seek care immediately if any of these occur.

⚠️Warnings & precautions▾
  • Severe skin reactions: Stevens-Johnson syndrome and toxic epidermal necrolysis (conditions where skin blisters and peels) can be fatal. Stop the drug at the first sign of any rash and call your doctor.
  • Serious blood disorders: This drug can cause dangerous drops in platelets (thrombocytopenia) and red or white blood cells — signs include unusual bruising, bleeding, or infections.
  • Lung injury: Serious breathing problems, including cases requiring a ventilator or lung transplant, have been reported — sometimes starting within days of first use.
  • Liver damage: Severe and even fatal liver failure has occurred. Watch for yellowing of skin or eyes.
  • Pregnancy risk: This drug may cause birth defects, particularly heart, neural tube, and urinary tract defects. Use only if clearly necessary and the benefit outweighs the risk.
  • Leucovorin interaction in PCP: Using leucovorin at the same time during PCP treatment has been linked to increased death rates — avoid this combination.
  • Propylene glycol toxicity: The IV formulation contains propylene glycol, which can cause dangerous acid-base imbalances if too much accumulates — your care team will monitor for this.
🔀What it interacts with▾

This drug can significantly affect the levels or effects of several other medications. Key interactions to know about:

  • Warfarin — SMX-TMP can increase warfarin's blood-thinning effect, raising bleeding risk; clotting tests need close monitoring
  • Phenytoin (Dilantin) — SMX-TMP slows phenytoin breakdown, which can cause it to build up to toxic levels; levels should be monitored
  • Methotrexate — SMX-TMP raises methotrexate to potentially dangerous levels; avoid using together
  • Cyclosporine — using together can cause serious kidney damage, especially in transplant patients; avoid
  • Digoxin — SMX-TMP can raise digoxin blood levels, especially in older adults; levels need to be checked
  • Dofetilide — this combination is completely contraindicated (must not be used together)
  • Thiazide diuretics (water pills) — higher risk of dangerous platelet drop in older adults; avoid combination
  • Indomethacin — can raise sulfamethoxazole levels in the blood; avoid concurrent use

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▾
  • Do not use if you have a known allergy to sulfa drugs or trimethoprim
  • Do not use if you have previously had a drug-caused drop in platelets (immune thrombocytopenia) from these drug types
  • Do not use if you have severe kidney disease and your kidney function cannot be tracked
  • Do not use if you have significant liver damage
  • Do not use if you have megaloblastic anemia caused by folate deficiency
  • Not for infants younger than two months old
  • Use during pregnancy only if the benefit clearly outweighs the risk — birth defects have been reported with first-trimester exposure
  • Avoid breastfeeding during treatment — the drug passes into breast milk and can be harmful to infants, particularly those with jaundice risk
  • Older adults may be more vulnerable to certain side effects, including platelet drops when combined with diuretics and elevated digoxin levels
  • Patients with reduced kidney function need dose adjustments and close monitoring
🚑If you take too much▾

Taking too much can cause nausea, vomiting, dizziness, headache, drowsiness, and in severe cases, confusion, blood in the urine, or dangerous drops in blood cell counts. Long-term use at high doses can suppress bone marrow — the part of your body that makes blood cells.

Treatment focuses on supportive care, including IV fluids if needed, and monitoring blood counts and chemistry. Hemodialysis can remove some of the drug but is only partially effective. If bone marrow suppression occurs, a medication called leucovorin may be given to help restore normal blood cell production.

📡Pharmacodynamics — effects in the body▾

This combination drug works by blocking two key steps in bacterial folate synthesis — the process bacteria use to make the folate they need to grow. Without functional folate, bacteria cannot produce the DNA building blocks they need to replicate. The result is that bacterial growth stops, and the immune system can clear the infection. This dual-blockade approach makes the combination more potent and harder for bacteria to resist than either drug alone.

🔬Pharmacokinetics — how your body processes it▾

When given as a one-hour IV infusion, both drugs reach measurable levels in the bloodstream quickly. The half-life — the time it takes for the body to clear half of the drug — is roughly 11 hours for trimethoprim and about 13 hours for sulfamethoxazole in adults with normal kidney function. Children tend to clear trimethoprim faster, so the half-life is shorter in younger patients. Because these drugs are primarily cleared by the kidneys, patients with kidney problems process them more slowly and need lower doses or may not be able to use the drug at all.

📦How to store it▾

Store at 20° to 25°C (68° to 77°F) . DO NOT REFRIGERATE.

📄 Written from Sulfamethoxazole / Trimethoprim’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 Sulfamethoxazole / Trimethoprim — the kind of thing our pharmacy team would talk through with you at the counter.

Why am I getting this antibiotic through an IV instead of just taking a pill? ▾
The IV form is used when your infection is serious enough that you need the medication working quickly and reliably, or when you're not able to take pills by mouth right now. Once you're stable and able to swallow medications, your doctor may switch you to an oral form. The IV gets the drug into your system faster and at consistent levels, which matters a lot with a serious infection.
What side effects should I actually expect, and which ones should make me call someone? ▾
The most common things people notice are nausea, vomiting, and skin rashes — those are uncomfortable but not usually dangerous on their own. What you want to report right away is any rash that's spreading, blistering, or peeling; unusual bruising or bleeding; difficulty breathing; yellowing of your skin or eyes; or severe diarrhea. Those can be signs of serious reactions that need immediate attention.
I take warfarin for my heart. Is that going to be a problem? ▾
Yes, this is something your care team needs to know about if they don't already. SMX-TMP can boost warfarin's blood-thinning effect, which raises your bleeding risk. Your doctors will likely check your blood clotting levels more frequently while you're on both drugs. Don't stop either medication on your own — just make sure everyone on your team knows you're on warfarin.
Is this medication safe if I'm pregnant or trying to become pregnant? ▾
This is a real concern. Some studies have found a possible link between this drug — especially in the first trimester — and certain birth defects, including heart and neural tube problems. It should only be used during pregnancy if your doctor decides the benefit of treating the infection clearly outweighs the risk to the baby. Make sure your care team knows you're pregnant or planning to become pregnant.
How will I know if the antibiotic is actually working? ▾
Your care team will be monitoring you closely — checking your symptoms, temperature, lab work, and possibly imaging depending on your infection. Most people start to feel some improvement within a few days, but it's important to complete the full course of treatment even if you feel better. Stopping early can allow the infection to come back or become resistant to antibiotics.
Why can't this medication be used in babies under two months old? ▾
Very young infants process drugs very differently than older babies and adults. The IV formulation contains benzyl alcohol, a preservative that can cause a dangerous reaction called 'gasping syndrome' in newborns — it can be life-threatening. For that reason, this medication is not approved for infants under two months of age, and alternative treatments are used in that age group.
Is Sulfamethoxazole / Trimethoprim available over the counter? ▾
Sulfamethoxazole / Trimethoprim 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 Sulfamethoxazole / Trimethoprim first available? ▾
Sulfamethoxazole / Trimethoprim has been available in the United States since at least 1983, based on FDA approval history (Drugs@FDA) and product marketing records.
Who makes Sulfamethoxazole / Trimethoprim? ▾
Sulfamethoxazole / Trimethoprim is supplied by 62 manufacturers listed in the FDA NDC Directory, including A-S Medication Solutions, Remedyrepack Inc., Teva Parenteral Medicines, Inc..

💬 Answers drafted from Sulfamethoxazole / Trimethoprim’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

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💊 How Sulfamethoxazole / Trimethoprim comes

Sulfamethoxazole / Trimethoprim is available in 3 forms. 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 vein
Available strengths 1 strength
80 mg/mL / 16 mg/mL
27 FDA-listed product records ⓘ

📊 Sulfamethoxazole / Trimethoprim across the U.S. market

How Sulfamethoxazole / Trimethoprim 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.

3
Dose forms ⓘ
62
Manufacturers
6
Brand names
272
FDA-listed product records ⓘ
1983
First marketed ⓘ

FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

A-S Medication Solutions16%
Remedyrepack Inc.7%
Teva Parenteral Medicines, Inc.6%
Bryant Ranch Prepack4%
Somerset Therapeutics, LLC4%
NuCare Pharmaceuticals,Inc.4%
Other makers60%

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

📈 How widely Sulfamethoxazole / Trimethoprim is used

A general measure of how commonly Sulfamethoxazole / Trimethoprim 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 Sulfamethoxazole / Trimethoprim 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.

2,217,156
Medicaid prescriptions filled (Q1–Q4 2025)
$21.5M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Sulfamethoxazole / Trimethoprim prescribed? Of the 1,596 medications we measure, Sulfamethoxazole / Trimethoprim ranks #100 by Medicaid prescriptions — more than 94% of them.

Where Sulfamethoxazole / Trimethoprim ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #100 of 1,596
#95 Oseltamivir 2,322,109 Rx #96 Insulin Lispro Injecti... 2,318,237 Rx #97 Methocarbamol 2,261,221 Rx #98 Tizanidine 2,254,693 Rx #99 Cefdinir 2,236,722 Rx #100 Sulfamethoxazole / Tri... 2,217,156 Rx #101 Carvedilol 2,202,041 Rx #102 Nystatin 2,190,507 Rx #103 Benzonatate 2,171,868 Rx #104 Apixaban 2,151,899 Rx #105 Lidocaine Transdermal... 2,146,915 Rx

Utilization by Sulfamethoxazole / Trimethoprim 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 800 mg / 160 mg oral tablet is the most-dispensed Sulfamethoxazole / Trimethoprim product — about 78% of these Medicaid prescriptions.

sulfamethoxazole 800 MG / trimethoprim 160 MG Oral Tablet Most dispensed

1,725,989 Medicaid prescriptions (Q1–Q4 2025) 78% of Sulfamethoxazole / Trimethoprim prescriptions shown $13.8M gross reimbursement (before rebates) ≈ $7.97 per prescription (gross)

Summed across the 12 of 386 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 198335

sulfamethoxazole 40 MG/ML / trimethoprim 8 MG/ML Oral Suspension

370,445 Medicaid prescriptions (Q1–Q4 2025) 17% of Sulfamethoxazole / Trimethoprim prescriptions shown $6.8M gross reimbursement (before rebates) ≈ $18 per prescription (gross)

Summed across the 4 of 43 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 313134

sulfamethoxazole 400 MG / trimethoprim 80 MG Oral Tablet

120,599 Medicaid prescriptions (Q1–Q4 2025) 5% of Sulfamethoxazole / Trimethoprim prescriptions shown $908,590 gross reimbursement (before rebates) ≈ $7.53 per prescription (gross)

Summed across the 9 of 49 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 198334

sulfamethoxazole 80 MG/ML / trimethoprim 16 MG/ML Injectable Solution

123 Medicaid prescriptions (Q1–Q4 2025) <1% of Sulfamethoxazole / Trimethoprim prescriptions shown $6,920 gross reimbursement (before rebates) ≈ $56 per prescription (gross)

Summed across the 3 of 13 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 313137

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 Sulfamethoxazole / Trimethoprim, 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 28 of 491 listed Sulfamethoxazole / Trimethoprim NDCs with Medicaid activity.

🔍 Compare Sulfamethoxazole / Trimethoprim products

A representative set of FDA-listed product records for Sulfamethoxazole / Trimethoprim — 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 200 of 272 products — FDA National Drug Code Directory. See every product, package size and price: browse all 272 Sulfamethoxazole / Trimethoprim 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) Sulfamethoxazole / Trimethoprim RxCUI 10831 4 dose forms · 7 strengths

Look up RxCUI 10831 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

Sulfatrim Sulfamethoxazole and Trimethoprim DS Bactrim Bactrim DS Sulfamethox-TMP DS

🏭 Manufacturers & labelers

A-S Medication Solutions 38 Remedyrepack Inc. 18 Teva Parenteral Medicines, Inc. 14 Bryant Ranch Prepack 10 Somerset Therapeutics, LLC 9 NuCare Pharmaceuticals,Inc. 9 RedPharm Drug, Inc. 9 Aurobindo Pharma Limited 8 Advanced Rx Pharmacy of Tennessee, LLC 7 American Health Packaging 6 PD-Rx Pharmaceuticals, Inc. 6 Amneal Pharmaceuticals of New York LLC 6 Preferred Pharmaceuticals Inc. 6 AvKARE 6 NuCare Pharmaceuticals, Inc. 5 Chartwell RX, LLC 5 Cardinal Health 107, LLC 5 St. Mary's Medical Park Pharmacy 5 Mylan Institutional LLC 4 Amneal Pharmaceuticals LLC 4 Proficient Rx LP 4 Cronus Pharma LLC 4 Denton Pharma, Inc. DBA Northwind Pharmaceuticals 4 Lannett Company, Inc. 4

…and 16 more on the FDA NDC directory.

RxNorm drug class

Sulfamethoxazole / Trimethoprim belongs to the Sulfonamide Antimicrobial class.

Pharmacologic class Sulfonamide Antimicrobial
Drug family (ATC) Intermediate-acting sulfonamides
How it works Cytochrome P450 2C9 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 Dec 30, 2024
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Sulfamethoxazole / Trimethoprim.
📈
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 Sulfamethoxazole / Trimethoprim after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
101
NDC products indexed
272
Distinct labelers/manufacturers represented
62
Linked representative label ⓘ
Sun Pharmaceutical Industries, Inc
Linked label effective
Dec 30, 2024
Composite sections available
23
Linked SPL Set ID
f59d0c04-9c66-4d53-a0e1-cb55570deb62
Linked SPL Document ID
2a76a544-1f84-4b42-e063-6394a90a08d5
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 101 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. Sun Pharmaceutical Industries, Inc 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.