Trimethoprim
.svg)
Drug Status
Government Approvals
US(FDA), UK(BNF)
WHO Essential Medicine
NO
Known Teratogen
Definite
Pharmaceutical Class
Dihydrofolate Reductase Inhibitor Antibacterial
Controlled Drug Substance
NO
Trimethoprim
Summary
Trimethoprim is used to treat bacterial infections, primarily urinary tract infections (UTIs) such as cystitis and kidney infections. It can also be used for chest infections, ear infections, and traveler's diarrhea. In some cases, it's used to prevent recurrent UTIs in people prone to infections.
Trimethoprim works by blocking the production of folic acid, a substance that bacteria need to grow and multiply. This helps stop the infection and allows the body's immune system to eliminate the bacteria.
For adults, the typical dose for a UTI is 100 mg twice daily or 200 mg once daily for 3 to 14 days. For children, the dose is based on body weight and divided into two doses. It is usually taken as a tablet or liquid.
Common side effects include nausea, vomiting, diarrhea, headaches, and skin rashes. Rare but serious effects include allergic reactions, liver problems, and blood disorders.
People allergic to Trimethoprim, pregnant women, especially in the first trimester, and those with kidney disease, folate deficiency, or blood disorders should avoid this medicine. Always inform your doctor of any health conditions before taking it.
Indications and Purpose
How does Trimethoprim work?
Trimethoprim works by blocking bacterial folic acid production, which is essential for bacterial growth. This prevents the bacteria from multiplying and allows the immune system to kill the remaining bacteria, clearing the infection.
Is Trimethoprim effective?
Yes, trimethoprim is highly effective in treating bacterial infections, especially UTIs. Studies show it successfully clears infections in 70-90% of cases when taken correctly. However, some bacteria are becoming resistant, so it is only prescribed when necessary.
What is Trimethoprim?
Trimethoprim is an antibiotic used to treat bacterial infections, mainly of the urinary tract (UTIs) and sometimes respiratory infections. It works by blocking the production of folic acid, which bacteria need to grow and multiply. This helps stop the infection and allows the body’s immune system to eliminate the bacteria. It is usually taken as a tablet or liquid.
Directions for Use
For how long do I take Trimethoprim?
The duration depends on the infection. For UTIs, trimethoprim is typically taken for 3 to 7 days. In cases of long-term prevention, it may be taken for several months. Do not stop taking it early, even if you feel better, as the infection may return or become resistant.
How do I take Trimethoprim?
Trimethoprim is usually taken once or twice daily, with or without food. Swallow the tablet with a glass of water. If taking the liquid form, measure it carefully. Avoid alcohol while on this medication, as it can increase side effects. Drink plenty of water to help flush out the infection.
How long does it take for Trimethoprim to start working?
Trimethoprim starts working within a few hours, but symptoms usually improve within 24 to 48 hours. However, it is essential to complete the full course to ensure all bacteria are eliminated. If symptoms do not improve in 3 days, consult your doctor.
How should I store Trimethoprim?
Store trimethoprim at room temperature (below 25°C) in a dry place, away from direct sunlight. Keep the liquid form refrigerated and discard any unused portion after 14 days. Keep out of reach of children.
What is the usual dose of Trimethoprim?
For adults, the typical dose for a UTI is 100 mg twice daily or 200 mg once daily for 3 to 14 days, depending on the severity. For children, the dose is based on body weight (3-6 mg/kg per day) and divided into two doses. Always follow your doctor's instructions and complete the full course.
Warnings and Precautions
Can I take Trimethoprim with other prescription drugs?
Trimethoprim can interact with methotrexate (used for cancer and arthritis), warfarin (a blood thinner), and some diuretics. These interactions can increase the risk of side effects like bleeding, high potassium levels, or toxicity. Inform your doctor of all medications you are taking.
Can Trimethoprim be taken safely while breastfeeding?
Yes, trimethoprim is generally safe while breastfeeding, as only small amounts pass into breast milk. However, it should be avoided in babies with premature birth, jaundice, or folate deficiency. If your baby develops diarrhea, fussiness, or skin rashes, inform your doctor.
Can Trimethoprim be taken safely while pregnant?
Trimethoprim is not recommended in early pregnancy as it may interfere with fetal development by reducing folic acid levels. If necessary, your doctor may prescribe folic acid supplements alongside it. Always consult your doctor before using it during pregnancy.
Is it safe to drink alcohol while taking Trimethoprim?
It is best to avoid alcohol while taking trimethoprim, as it can increase side effects like nausea, dizziness, and drowsiness. Drinking in moderation may not cause severe issues, but excessive alcohol use can worsen the infection and affect liver function.
Is it safe to exercise while taking Trimethoprim?
Yes, light to moderate exercise is generally safe. However, if you feel weak, dizzy, or fatigued, avoid strenuous activity. Stay hydrated and listen to your body while recovering from the infection.
Is Trimethoprim safe for the elderly?
Elderly patients should take trimethoprim with caution, as they are more prone to kidney problems, high potassium levels, and folate deficiency. Dose adjustments may be needed, and regular blood tests may be required to monitor for side effects.
Who should avoid taking Trimethoprim?
People allergic to trimethoprim or sulfonamide antibiotics, pregnant women (especially in the first trimester), and those with kidney disease, folate deficiency, or blood disorders should avoid this medicine. Always inform your doctor of any health conditions before taking it.
Forms / Brands
