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Trimethoprim

To reduce the development of drug-resistant bacteria and maintain the effectiveness of trimethoprim tablets, USP and other antibacterial drugs, trimet.

Checked against the official label · Updated

Prescription medicine Oral Safety alerts on record

How to use Trimethoprim

What the official label says. If a doctor prescribed it, follow the prescription. Your pack's leaflet comes first if it is different.

Who it is for

To reduce the development of drug-resistant bacteria and maintain the effectiveness of trimethoprim tablets, USP and other antibacterial drugs, trimethoprim tablets, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy. …

How to take it and how often
  • The usual oral adult dosage is 100 mg of trimethoprim every 12 hours or 200 mg of trimethoprim every 24 hours, each for 10 days
  • The use of trimethoprim in patients with a creatinine clearance of less than 15 mL/min is not recommended
  • For patients with a creatinine clearance of 15 to 30 mL/min, the dose should be 50 mg every 12 hours
Children
  • Safety and effectiveness
  • In pediatric patients below the age of 2 months have not been established
  • The effectiveness of trimethoprim as a single agent has not been established
  • In pediatric patients under 12 years of age
Older adults

Clinical studies of trimethoprim tablets did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience 4,5 has not identified differences in response between the elderly and younger patients. …

While you are taking it
  • Patients should be counseled that antibacterial drugs including trimethoprim tablets, USP should only be used to treat bacterial infections
  • They do not treat viral infections (e.g., the common cold)
  • When trimethoprim tablets, USP are prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. …
Talk to a doctor first if

Trimethoprim is contraindicated in individuals hypersensitive to trimethoprim and in those with documented megaloblastic anemia due to folate deficiency.

Medicines it may not mix with

Trimethoprim may inhibit the hepatic metabolism of phenytoin. Trimethoprim, given at a common clinical dosage, increased the phenytoin half-life by 51% and decreased the phenytoin metabolic clearance rate by 30%. When administering these drugs concurrently, one should be alert for possible excessive phenytoin effect.

Warnings

Serious hypersensitivity reactions have been reported rarely in patients on trimethoprim therapy. Trimethoprim has been reported rarely to interfere with hematopoiesis, especially when administered in large doses and/or for prolonged periods. The presence of clinical signs such as sore throat, fever, pallor, or purpura may be early indications of serious blood disorders (see OVERDOSAGE , Chronic ). Complete blood counts should be obtained if any of these signs are noted in a patient receiving trimethoprim and the drug discontinued if a significant reduction in the count of any formed blood element is found. …

Possible side effects

The adverse effects encountered most often with trimethoprim were rash and pruritus. Dermatologic Rash, pruritus, and phototoxic skin eruptions. At the recommended dosage regimens of 100 mg b.i.d. or 200 mg q.d., each for 10 days, the incidence of rash is 2.9% to 6.7%. In clinical studies which employed high doses of trimethoprim, an elevated incidence of rash was noted. These rashes were maculopapular, morbilliform, pruritic, and generally mild to moderate, appearing 7 to 14 days after the initiation of therapy. …

Pregnancy and breastfeeding

Pregnancy Teratogenic Effects Pregnancy category C Trimethoprim has been shown to be teratogenic in the rat when given in doses 40 times the human dose. In some rabbit studies, the overall increase in fetal loss (dead and resorbed and malformed conceptuses) was associated with doses six times the human therapeutic dose. …

If you take too much

Acute Signs of acute overdosage with trimethoprim may appear following ingestion of 1 gram or more of the drug and include nausea, vomiting, dizziness, headaches, mental depression, confusion, and bone marrow depression (see Chronic subsection). Treatment consists of gastric lavage and general supportive measures. Acidification of the urine will increase renal elimination of trimethoprim. Peritoneal dialysis is not effective and hemodialysis only moderately effective in eliminating the drug. …

If you miss a dose

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.

From the official U.S. FDA label for this active ingredient. Your pack may have a different strength, so always read its leaflet. If a doctor prescribed it, follow the prescription. Ask a pharmacist if you are unsure. Label dated 2024-06-04.

Brands around the world

Products with Trimethoprim as the active ingredient. Names differ between countries.

Registered products

United States (FDA)

Sulfamethoxazole And TrimethoprimSULFAMETHOXAZOLE 800 mg/1, TRIMETHOPRIM 160 mg/1 · Tablet · Vista Pharmaceuticals, Inc.
NDC 61971-120Label
Sulfamethoxazole And TrimethoprimSULFAMETHOXAZOLE 800 mg/1, TRIMETHOPRIM 160 mg/1 · Tablet · NCS HealthCare of KY, LLC dba Vangard Labs
NDC 0615-8121Label
Sulfamethoxazole And TrimethoprimSULFAMETHOXAZOLE 200 mg/5mL, TRIMETHOPRIM 40 mg/5mL · Suspension · Prasco Laboratories
NDC 66993-727Label
Sulfamethoxazole And TrimethoprimSULFAMETHOXAZOLE 800 mg/20mL, TRIMETHOPRIM 160 mg/20mL · Suspension · Chartwell Governmental & Specialty RX, LLC.
NDC 68999-873Label
Sulfamethoxazole And TrimethoprimSULFAMETHOXAZOLE 800 mg/1, TRIMETHOPRIM 160 mg/1 · Tablet · St. Mary's Medical Park Pharmacy
NDC 60760-541Label

Nigeria (NAFDAC)

NAFDACNecotrim 04-2377NAFDACCaretrim A4-0213NAFDACCotrikris A4-5655NAFDACTutrim Tablet 04-9173NAFDACEmtrim Tablet 04-0267NAFDACQ-Tib Tablets B4-9116NAFDACButrim Tablets A11-100207NAFDACSamtrim Tablet 04-0277NAFDACTrimac Tablets B4-4731NAFDACCo-Trox Tablet 04-0061NAFDACKistrim Tablet A4-6612NAFDACPrimpex Tablet 04-1959

Other countries: check your pack's registration number and we point you to your regulator.

Safety alerts and recalls

Sulfamethoxazole and Trimethoprim Tablets, USP 800mg / 160mg Double Strength packaged in a) 6-count bottles (NDC 51655-307-87), b) 10-count bottles (NDC 51655-307-53), c) 14-count U.S. FDA Class II
20 Aug 2025 · Northwind Pharmaceuticals LLC · OngoingPresence of a Foreign Substance: A specific lot of auxiliary polyester coil, used in product packaging by manufacturer (Amneal Pharmaceuticals LLC) was detected with presence of a micro-organism. No micro-organism was detected on any tablets.
Sulfamethoxazole and Trimethoprim, USP, 800 mg/160 mg, Double Strength, 10 Tablets unit dose blister pack (10x1) per bag, Rx only, Distributed by Cardinal Health, Dublin, OH 43017,U.S. FDA Class II
2 Sep 2025 · The Harvard Drug Group LLC dba Major Pharmaceuticals and Rugby Laboratories · OngoingPresence of a Foreign Substance: A specific lot of auxiliary polyester coil, used in product packaging by manufacturer (Amneal Pharmaceuticals LLC) was detected with presence of a micro-organism. No micro-organism was detected on any tablets.
Sulfamethoxazole and Trimethoprim, USP, 800 mg/160 mg, Double Strength, 100 Tablets unit dose blister packs (10x10) per carton, Rx only, Packaged and Distributed by: Major PharmacU.S. FDA Class II
2 Sep 2025 · The Harvard Drug Group LLC dba Major Pharmaceuticals and Rugby Laboratories · OngoingPresence of a Foreign Substance: A specific lot of auxiliary polyester coil, used in product packaging by manufacturer (Amneal Pharmaceuticals LLC) was detected with presence of a micro-organism. No micro-organism was detected on any tablets.
Sulfamethoxazole and Trimethoprim Tablets, USP 800mg/160mg, Double Strength, Rx Only, Packaged as a) 100-count bottle, NDC 65162-272-10; b) 500-count bottle, NDC 65162-272-50; ManU.S. FDA Class II
18 Aug 2025 · Amneal Pharmaceuticals, LLC · OngoingPresence of a foreign substance.A specific lot of auxiliary polyester coil, used in product packaging was detected with presence of a micro-organism. No micro-organism was detected on any tablets.

A recall usually affects certain batches only. Compare the lot number on your pack.

Check your pack of Trimethoprim

Type the registration number on the pack, or scan it with your camera.

Or take photos of the pack
3 free checks left today Official sources: U.S. FDA · EMA (EU) · Health Canada · WHO alerts

Questions about Trimethoprim

What is Trimethoprim used for?

To reduce the development of drug-resistant bacteria and maintain the effectiveness of trimethoprim tablets, USP and other antibacterial drugs, trimethoprim tablets, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacteria (From the official U.S. FDA label.)

How do I take Trimethoprim?

Follow your prescription or the leaflet in your pack. The official label says: The usual oral adult dosage is 100 mg of trimethoprim every 12 hours or 200 mg of trimethoprim every 24 hours, each for 10 days. The use of trimethoprim in patients with a creatinine clearance of less than 15 mL/min is not recommended. For patients with a creatinine clearance of 15 to 30 mL/min, the dose should be 50 mg every 12 hours.…

Do I need a prescription for Trimethoprim?

Usually yes. Trimethoprim is a prescription medicine in most countries. Rules differ by country.

What brands contain Trimethoprim?

Trimethoprim is sold under names such as Bactrim, Equisul Sdt, Sulfatrim, Primsol, Uniprim. Brand names differ between countries.

What are the side effects of Trimethoprim?

The official label lists: The adverse effects encountered most often with trimethoprim were rash and pruritus. Dermatologic Rash, pruritus, and phototoxic skin eruptions. At the recommended dosage regimens of 100 mg b.i.d. or 200 mg q.d., each for 10 days, the incidence of rash is 2.9% to 6.7%. In clinical studies which employed high doses of trimethoprim, an elevated incidence of rash was noted. These… Tell your doctor about any side effect that bothers you or does not go away.

Can children take Trimethoprim?

Safety and effectiveness in pediatric patients below the age of 2 months have not been established. The effectiveness of trimethoprim as a single agent has not been established in pediatric patients under 12 years of age. Always use the dose for the child's age or weight on the pack or prescription.

Can I take Trimethoprim when pregnant or breastfeeding?

Pregnancy Teratogenic Effects Pregnancy category C Trimethoprim has been shown to be teratogenic in the rat when given in doses 40 times the human dose. In some rabbit studies, the overall increase in fetal loss (dead and resorbed and malformed conceptuses) was associated with doses six times the human therapeutic dose. … Ask your doctor or midwife first.

What medicines interact with Trimethoprim?

Trimethoprim may inhibit the hepatic metabolism of phenytoin. Trimethoprim, given at a common clinical dosage, increased the phenytoin half-life by 51% and decreased the phenytoin metabolic clearance rate by 30%. When administering these drugs concurrently, one should be alert for possible excessive phenytoin effect. Use the free interaction checker before combining medicines.

What happens if I take too much Trimethoprim?

Acute Signs of acute overdosage with trimethoprim may appear following ingestion of 1 gram or more of the drug and include nausea, vomiting, dizziness, headaches, mental depression, confusion, and bone marrow depression (see Chronic subsection). Treatment consists of gastric lavage and general suppo… Get medical help right away.

How can I check that my Trimethoprim is genuine?

Scan the registration number on your pack with PillVera (NAFDAC number in Nigeria, NDC in the United States, DIN in Canada), check the expiry date and buy only from licensed pharmacies.

Sources

This page shows what official sources say, in plain words. It is not medical advice: your prescription and your doctor or pharmacist come first. Brand names, strengths and rules differ between countries.