Trimethoprim: uses, dosing, side effects & brands

Trimethoprim is a medicine sold in the U.S. under 5 brand and generic names. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.

By the pharmaranks editorial teamReviewed against the FDA (openFDA label, NDC Directory & Enforcement) sourcesUpdated Jul 24, 2026How we research

Key facts

Available as: Tablet · Solution
Sold as: 5 products — Trimethoprim, Primsol and Proloprim, and others
Prescription?: Prescription only
Generic available?: Yes
Half-life: about 8 to 10 hours
What the pharmacy pays: about $35 for a 30-count supply — not your price

Every trimethoprim product we track (5)

Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.

Trimethoprim products
#	Drug	Rating	Type	Form	Generic?	Pharmacy pays
1	Trimethoprim	54/100	Prescription	Tablet	Generic	$35	View →
2	Primsol	Not yet rated	Prescription	Solution	Generic	$35	View →
3	Proloprim	Not yet rated	Prescription	Tablet	Generic	$35	View →
4	Trimpex	Not yet rated	Prescription	Tablet	Generic	$35	View →
5	Trimpex 200	Not yet rated	Prescription	Tablet	Generic	$35	View →

Combination products containing trimethoprim

A combination is a different drug — different dosing, different warnings. It is listed here so you can find it, not so you can substitute it.

Trimethoprim recalls

From the FDA Enforcement database. A recall covers specific lots — not the drug as a whole.

How long trimethoprim keeps

No trimethoprim label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.

Trimethoprim and breastfeeding

From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.

Because of the low levels of trimethoprim in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants.

Full LactMed record for trimethoprim: levels in milk, effects in breastfed infants, and the drugs it would consider instead

National Institute of Child Health and Human Development, record revised November 15, 2024. LactMed states its information is not a substitute for professional judgement.

What people report to the FDA about trimethoprim

The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 71,884 reports naming trimethoprim, and the FDA flagged 91% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:

pyrexia6,696 reports
rash5,429 reports
fatigue5,209 reports
dyspnoea5,036 reports
diarrhoea4,543 reports
nausea4,433 reports
pruritus4,130 reports
vomiting4,036 reports

Read these as a signal, not a rate. A report does not mean trimethoprim caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label.

Source: openFDA drug/event (FAERS), retrieved August 26, 2026.

How long trimethoprim stays in your system

The elimination half-life of trimethoprim is about 8 to 10 hours. This is the elimination half-life in adults with normal kidney function, so trimethoprim is largely cleared in roughly 2 days (about 5 half-lives). Trimethoprim is not a prodrug and has no active metabolite that outlasts it — only 10-20% is metabolized (mostly in the liver to inactive oxide and hydroxy derivatives), and the free (unchanged) drug is the therapeutically active form, with the rest excreted unchanged in urine. Because clearance is mainly renal, the half-life lengthens in people with severely impaired kidney function, which calls for dose adjustment or avoiding the drug. Half-life is a clearance measure, not a drug-test detection window.

TRIMETHOPRIM tablet — DailyMed (Clinical Pharmacology) ↗

Half-life is how long the body takes to clear half a dose. It is not the same as how long a drug test can detect it, and it varies with age, kidney and liver function.

Related calculators

How long it stays in your system →

Frequently asked questions

How long does trimethoprim stay in your system?

The elimination half-life of trimethoprim is about 8 to 10 hours — that is how long the body takes to clear half of a dose. This is the elimination half-life in adults with normal kidney function, so trimethoprim is largely cleared in roughly 2 days (about 5 half-lives). Trimethoprim is not a prodrug and has no active metabolite that outlasts it — only 10-20% is metabolized (mostly in the liver to inactive oxide and hydroxy derivatives), and the free (unchanged) drug is the therapeutically active form, with the rest excreted unchanged in urine. Because clearance is mainly renal, the half-life lengthens in people with severely impaired kidney function, which calls for dose adjustment or avoiding the drug. Half-life is a clearance measure, not a drug-test detection window. Half-life is not the same as how long a drug test can detect the drug, and it varies with age, kidney and liver function.

Can you take trimethoprim with other medicines?

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run trimethoprim against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

What brand names is trimethoprim sold under?

We track 5 trimethoprim-containing products in the U.S.: Trimethoprim, Primsol, Proloprim, Trimpex and Trimpex 200. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

What forms does trimethoprim come in?

Across the brands we track, trimethoprim is currently marketed as tablet and solution, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Is there a generic trimethoprim?

Yes. Our catalog lists 1 generic trimethoprim product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

Has trimethoprim been recalled?

The FDA's Enforcement database lists at least 5 recall records whose product description mentions trimethoprim. The most recent: Sulfamethoxazole and Trimethoprim (Sep 2, 2025). A recall applies to specific lots, not to the drug as a whole — check the record for the affected lot numbers.

Cite this page

APA: pharmaranks. (2026, July 24). Trimethoprim: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/trimethoprim
MLA: “Trimethoprim: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/trimethoprim.

We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.

Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.

Read the full FDA label for trimethoprim on DailyMed (NIH) ↗.