Trimethoprim Tablets

Trimethoprim is a synthetic antibacterial drug with bacteriostatic activity, that is, it cannot kill bacterial cells, but it can inhibit ...
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About Trimethoprim Tablets

Trimethoprim is an antibiotic used to treat bladder (cystitis) and urinary tract infections (UTIs). It is included on the World Health Organization's List of Essential Medicines.

Taking a three day course of Trimethoprim will clear most bladder and urinary tract infections. However, if your symptoms have not improved once you have completed your medication, you should seek advice from your GP.

Most cases of cystitis or UTIs are caused by E.coli, which originates in your gut. Trimethoprim does not kill E.coli. Instead, it stops bacterial DNA synthesis, meaning that the bacteria cannot replicate. This allows your immune system to destroy the infecting bacteria until they are eradicated and your infection is resolved.

People also ask

What is Trimethoprim?

Trimethoprim is a synthetic antibacterial drug with bacteriostatic activity, that is, it cannot kill bacterial cells, but it can inhibit their growth. Trimethoprim is generally given in combination with various types of sulfonamides (other antibacterial drugs). The association of these two types of antibacterials is capable of exerting a bactericidal action on bacterial cells. Furthermore, the combination induces less resistance than that induced by the two drugs used individually. However, if the bacteria treated with the trimethoprim-sulfonamide combination already have resistance against one of the two antimicrobials, the advantage of administration of the combination is nullified. There are several associations between trimethoprim and sulfonamides, the most famous and most widely used is probably the one that gives rise to cotrimoxazole. Cotrimoxazole is nothing but an antibacterial consisting of the combination of sulfamethoxazole and trimethoprim in a fixed ratio of 5: 1.

How does it work?

Trimethoprim inhibits the enzyme dihydrofolate reductase. In many microorganisms, the effectiveness of this enzyme is about 50,000 times greater than that corresponding to the enzyme present in mammalian cells, which explains the wide therapeutic range of trimethoprim. Dihydrofolate reductase participates in the conversion of dihydrofolic acid to its functional form, tetrahydrofolic acid. Its inhibition depletes folate reserves, an essential cofactor in purine biosynthesis, and, ultimately, of bacterial DNA, so its inhibition prevents the microorganism from dividing. Along with sulfa drugs, trimethoprim produces a sequential block of the metabolic chain, so that both drugs are synergistic when they work together.

What are the benefits of taking it?

Trimethoprim is an antibiotic. This medication prevents protein production in bacteria and causes them to die. The active substance is absorbed into the blood and thus reaches the inflamed tissues and urine. Trimethoprim can only be obtained by prescription.

Doctors prescribe trimethoprim as an antibiotic treatment for various infections, such as:

Cystitis in women and other urinary tract infections. This medication can also be used to prevent recurrent bladder infections; Respiratory infections, such as pneumonia, Middle ear infections, sinus infections, and acute bronchitis.

The active substance trimethoprim works quickly. After a few days, you will already notice that inflammatory reactions, such as pain, fever, and a general feeling of being unwell, have subsided.

How do I use it?

Take the cystitis treatment medicinal tablet with a little water without chewing it. The doctor determines how long you have to take this medicine in total. It is important that you complete the prescribed treatment. If the dose is stopped too soon, the infection may come back. If you are taking this medicine to treat cystitis, take the tablets when you go to bed. In this way, the medicine can act on the bladder overnight.

Its dosage

Trimethoprim is available in different strengths. The doctor determines which force best suits your symptoms. Unless the doctor directs otherwise, the generally recommended dose of trimethoprim is as follows:

  • Adults and children from 12 years: 200 mg twice a day. If you have a bladder infection, your doctor may recommend that you take 300 mg once a day.
  • A different dosage recommendation applies to children under the age of 12. Follow the recommended dose and read the package leaflet before taking it.

Side effects & precautions

Seek emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of the face, lips, tongue, or throat.

Call your doctor immediately if you have:

  • severe stomach pain, diarrhea that is watery or bloody (even if it occurs months after your last dose)
  • pale, gray, or bluish skin
  • fever, weakness
  • sore or swollen tongue
  • easy bruising, purple or red spots under the skin
  • rash, no matter how mild it is
  • high potassium level - nausea, weakness, tingling sensation, chest pain, irregular heartbeat, loss of movement.

Common side effects may include:

  • vomiting, diarrhea, stomach pain
  • rash, itching
  • swelling on your tongue


Antibiotics can react with other medications and affect their effectiveness. Inform your doctor during the consultation of any other medicine you are using. Never use more than one product or medication for cystitis unless your doctor tells you to.

If you are taking any of the following treatments, you may not be able to use Trimethoprim, or only be able to use it under medical supervision: repaglinide, procainamide, digoxin, diuretics, rifampin, anticoagulants, phenytoin, pyrimethamine, dapsone or immunosuppressant drugs.


Bacterial resistance to trimethoprim may be the result of a reduction in cell permeability, overproduction of the enzyme dihydrofolate reductase, or the production of a conformationally reduced reductase with decreased affinity for the antibiotic. Said forms of resistance can appear by mutation or, more frequently, by the intervention of resistant plasmid-encoded reductases.4 These reductase enzymes can be encoded within the transposons of conjugated plasmids, characterized by showing a wide range of microbial hosts. This would explain the rapid and extensive spread of resistance to trimethoprim among numerous bacterial species.

Buying Trimethoprim online.

You can buy Trimethoprim online through one of the UK’s leading online pharmacies, Pharmacy Planet. It's easy and convenient. You will need to fill out a short assessment and the item will be delivered directly to your door. If you want to buy Trimethoprim 200mg Tablets online, use Pharmacy Planet, a UK pharmacy you can trust.
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