trimethoprim vs warfarin
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Side-by-side comparison of trimethoprim and warfarin. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
minor Known Drug Interaction
It has been reported that sulfamethoxazole and trimethoprim may prolong the prothrombin time in patients who are receiving the anticoagulant warfarin (a CYP2C9 substrate).
Primsol
Coumadin, Jantoven
This medicine contains sulfamethoxazole and trimethoprim. It is an antibiotic that fights bacteria in your body.
Warfarin is a medicine that helps prevent blood clots. It is used to treat and prevent dangerous clots from forming in your body.
This medicine can treat urinary tract infections, ear infections in children, and bronchitis in adults. It also treats shigellosis, a type of diarrhea. It can also treat or prevent Pneumocystis jiroveci pneumonia, and treat traveler's diarrhea.
Warfarin is used to prevent and treat blood clots in your veins and lungs. It can also prevent clots if you have atrial fibrillation (irregular heartbeat) or a replacement heart valve. After a heart attack, it can lower the risk of death, another heart attack, or a stroke.
This medicine works by stopping bacteria from making folic acid. Bacteria need folic acid to grow and multiply. By blocking folic acid production, the medicine kills the bacteria.
Warfarin works by blocking your body's use of vitamin K. Vitamin K is needed to make blood clotting factors. By blocking vitamin K, warfarin makes your blood less likely to clot.
- • Nausea
- • Vomiting
- • Loss of appetite
- • Skin rash
- • Hives
- • Bleeding from any tissue or organ
- Nausea 945
- Diarrhoea 848
- Headache 835
- Malaise 816
- Pyrexia 721
- International Normalised Ratio Increased 10,276
- Dyspnoea 8,408
- Drug Interaction 6,288
- Fatigue 6,143
- Nausea 5,921
Rarely, sulfonamide drugs like this one have caused severe reactions. These include Stevens-Johnson syndrome, toxic epidermal necrolysis, liver damage, and blood problems. Tell your doctor right away if you have a fever, rash, blisters, mouth sores, or signs of infection.
Warfarin can cause major or fatal bleeding. You must have your blood tested regularly (INR) while taking warfarin. Many things, like other medicines and diet changes, can affect your INR. Tell your doctor about any bleeding and follow their instructions to prevent bleeding.
Tell your doctor if you are pregnant or plan to become pregnant. This medicine may not be safe for your baby. Talk to your doctor about the risks and benefits of taking this medicine while breastfeeding.
Warfarin can harm your unborn baby, especially during the first three months of pregnancy. Do not take warfarin if you are pregnant, unless you have a mechanical heart valve and your doctor says the benefits outweigh the risks. Talk to your doctor if you are breastfeeding, and watch your baby for bruising or bleeding.
How to Read This trimethoprim vs warfarin Comparison
trimethoprim is classified in the Dihydrofolate Reductase Inhibitor drug class, while warfarin sits within the Vitamin K Antagonist (Anticoagulant) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, trimethoprim has 4,165 submissions while warfarin has 37,036. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to trimethoprim slows down how your body processes warfarin, which can make your blood thinner and increase your risk of bleeding.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for trimethoprim or warfarin.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.