Trimethoprim - Uses - Dosages - Side Effects - Precautions

Trimethoprim: Frequently Asked Questions Answered

What is Trimethoprim?

Trimethoprim is an antibiotic that belongs to a class of drugs called sulfonamides, containing sulfonamide chemical groups. The other class of antibiotics includes penicillin, amoxicillin, and metronidazole. It suppresses the development of bacteria in the human body and treats bacterial infections. Trimethoprim is available as a pill that must be swallowed. It’s commonly taken once or twice per day. Trimethoprim is an antibiotic that can be taken with or without food. The drug inhibits the growth of susceptible bacteria by interfering with the production of folic acid.

What are the uses of Trimethoprim?

Trimethoprim is an antibiotic prescription medication used to prevent or treat certain bacterial infections, such as urinary tract infections (UTIs), ear infections, bronchitis, traveler’s diarrhea, and shigellosis. Trimethoprim may also be used for purposes not listed in this medication guide. You should not use Trimethoprim if you are allergic to it.

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What are the side effects of Trimethoprim?

Trimethoprim side effects include upset stomach, diarrhea, and rash. These side effects usually go away after you stop taking the medication. If these effects persist or worsen over time, you should notify your healthcare provider. 

Some severe side effects that require immediate treatment are kidney or liver damage, which can occur if you take sulfa drugs such as Bactrim or Septra.

If you have further queries on the precautions, uses, and dosages, and side effects of Trimethoprim, our experts at Yashoda Hospitals are a call away.

S.no Product Name Dosage Form
1. Bacstol Trimethoprim 100mg/200mg Tablet
2. Bactrim DS Sulphamethoxazole 800mg+trimethoprim 160mg Tablet
3. Septran Sulphamethoxazole 200mg+trimethoprim 40mg Suspension
4. Bactrim Sulphamethoxazole 200mg+trimethoprim(cotrimoxazole)40mg Suspension
5. Jolltrim Sulphamethoxazole 800mg+trimethoprim 160mg Tablet


Frequently Asked Questions about Trimethoprim

1. Is Trimethoprim a strong antibiotic?

Yes. Trimethoprim is a strong antibiotic. Trimethoprim kills bacteria in the body by blocking functions that are needed for bacteria to grow and multiply. It attaches to chemicals called 'dihydrofolate reductase' that are part of the B-12 pathway, allowing bacteria to produce essential components and blocking this function prevents them from multiplying.

2. Is Trimethoprim a sulfa drug?

No. Trimethoprim is a member of the sulfonamide family. Sulfa drugs are so named because they contain a sulfonamide moiety (SO2NH2). Trimethoprim is a synthetic drug that has no chemical relationship to sulfonamide antibiotics. Instead of being sulfa drugs, trimethoprim and its relatives are referred to as antimicrobials.

3. Can I take Metronidazole and Trimethoprim together?

No. Trimethoprim is used to treat specific infections caused by bacteria, such as urinary tract infections (UTIs) and respiratory or ear infections. Metronidazole is a medicine used to treat bacterial, parasitic, and viral infections. This combination is not recommended. Taking these medications together increases your risk for a serious condition called rhabdomyolysis. Rhabdomyolysis can damage your kidneys and may be life-threatening.

4. Is Trimethoprim safe in pregnancy?

No. Trimethoprim is a cidal form of trimethoprim sulfa antibiotic used to treat urinary tract infections, sepsis, shigellosis, toxoplasmosis, and Pneumocystis carinii pneumonia. This drug is contraindicated in pregnant women and children as it might cause congenital abnormalities in the fetus.

5. Can Trimethoprim delay your period?

Yes. As the medication trimethoprim is used to treat UTI infection in the uterus. It can cause hormonal imbalance resulting in delayed periods. The fear of infection and stress related to it is enough to cause a delay in periods. However, seeking medical advice before using trimethoprim is a good precautionary measure.

6. Does Trimethoprim contain penicillin?

No. Trimethoprim does not contain penicillin, but it can be a component in some drugs that are considered to be antibiotics like penicillin. Trimethoprim contains the active ingredient sulfamethoxazole, which functions as a bacteriostatic antibiotic that affects the bacterial synthesis of dihydrofolic acid by inhibiting the enzyme dihydropteroate synthetase.

7. What class of antibiotics is Trimethoprim?

Trimethoprim is a member of a class of antibiotics known as sulfonamides. Trimethoprim is a bacteriostatic antibiotic used primarily to treat urinary tract infections. It is also sometimes used to treat upper respiratory infections, and prophylactically to prevent recurrent bladder infections in those who have had more than two such infections within six months.

8. Is Trimethoprim stronger than Amoxicillin?

Trimethoprim is a form of antibiotic that falls under the larger umbrella term ‘sulfa antibiotic’. Amoxicillin also falls under the category of penicillin, which are antibiotics derived from mold. The two medications have different intended purposes, and one may be more effective than the other for certain bacterial infections; however, they both work in a very similar manner.

9. Is 3 days of Trimethoprim enough?

No. Trimethoprim (TMP) is an antibiotic used for UTI and prevention, but it has a short half-life. This means that after 3-days of taking TMP, the concentration of TMP in your body will be cut by half. It doesn't make sense to take this medication longer than necessary, but most guidelines recommend 7-days.

10. Who should not take Trimethoprim?

Some may not be able to take trimethoprim. There are conditions that may make it unsafe for you to do so. If you've had a serious allergic reaction to a sulfa drug, kidney disease, or a metabolic disorder, are pregnant, or are 65-years or older, you should talk with your doctor before taking the medication.

For further queries regarding dissimilar health-related issues or medications, consult our experts at Yashoda Hospitals, a call away.



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      Disclaimer: The information provided herein is accurate, updated and complete as per the best practices of the Company. Please note that this information should not be treated as a replacement for physical medical consultation or advice. We do not guarantee the accuracy and the completeness of the information so provided. The absence of any information and/or warning to any drug shall not be considered and assumed as an implied assurance of the Company. We do not take any responsibility for the consequences arising out of the aforementioned information and strongly recommend you for a physical consultation in case of any queries or doubts.