• Trimethoprim

Trimethoprim 200mg

Medication features

Trimethoprim 200mg is an antibiotic used to treat urinary tract infections by killing the bacteria causing the infection. It helps relieve symptoms like pain and burning during urination.

  • Twice daily dosage 
  • Three day course (200mg x 6)
  • NOT suitable in pregnancy


Trimethoprim 200mg Tablets Online

You can request to buy Trimethoprim online from our UK registered online pharmacy and doctor service. No prescription is required, however, you will need to complete an online assessment, so our doctors can issue a prescription to our UK pharmacy. If the doctors approve your order, a prescription is passed to our pharmacy, which will then dispense and dispatch your medication.

If our doctors feel a face to face consultation would be best for you, a notification is sent via e-mail and a full refund is issued.

What is Trimethoprim?

Trimethoprim is an antibiotic used to treat urinary tract infections. It is the most commonly the first treatment prescribed by doctors for uncomplicated lower urinary tract infections known as cystitis. This medication contains 200mg of the active ingredient which works to kill the bacteria which causes the infection.

Trimethoprim for UTIs

A urinary tract infection occurs when bacteria enters the urinary tract which is usually a bacteria-free environment. When the bacteria enters the lower urinary tract and causes inflammation, this is known as cystitis. The inflammation caused by the bacteria is what gives UTIs its characteristic symptoms of discomfort, urgently needing the bathroom, pain on urination and needing the bathroom frequently.

Bacteria can move further up the urinary tract and into the kidneys causing flank, back or side pain. If this happens seek medical attention immediately as it is a serious form of UTI known as an upper urinary tract infection.

When buying trimethoprim tablets online, only use the medicine for cystitis after an online assessment. 

Chronic Cystitis

How does Trimethoprim work?

Trimethoprim works directly on the affected area travelling to the bladder. Here trimethoprim attacks the bacteria, preventing them from multiplying. This allows the immune system to come and clear the remaining bacteria and infection.

This is why it is recommended to take trimethoprim at night. It allows the medicine to remain in the bladder longer where it works effectively before leaving the body through the urine.

Trimethoprim Dose

For urinary tract infections, the most common course is 3 days. One tablet is taken TWICE daily (every 12 hours). For more stubborn infections, it may also be prescribed for five days.

Trimethoprim will take start to relieve symptoms in as little as 24 hours although the full effect can take up to 3 days. If symptoms are still present after the 3-day course, consult your doctor as soon as possible for continued treatment or alternative antibiotics.

Even if symptoms go away before completing your course, you should make sure to finish the tablets prescribed. This is to make sure the infection has been completely cleared, reducing the risk of it coming back. Stopping your course early can lead to resistance to trimethoprim in the bacteria, known as antibiotic resistance.

Trimethoprim Summary

Type of medicine

Antibiotic - broad spectrum


One tablet TWICE daily for three days



Side Effects

Can include itching, diarrhoea, nausea, vomiting and stomach upset

Active Ingredient

Trimethoprim 200mg


Prevents UTI bacteria from multiplying

Side effects of Trimethoprim

As with all medications, there are some side effects, although not everybody gets them. Potential trimethoprim side effects can be:

  • Headaches
  • Rashes & hives
  • Nausea 
  • Stomach upset
  • Thrush

Serious side effects such as allergic reactions can cause difficulty breathing, severe rashes and swelling. While these are very rare, if experienced, seek medical attention immediately.

A full list of side effects can be seen in the patient information leaflet and it is always advised you read this prior to taking any medication.

Trimethoprim Alternatives

Aside from Trimethoprim, there are a number of other antibiotics that are used in the treatment of UTIs. Macrobid and the generic version, Nitrofurantoin, are also available via the online doctor service.

Apart from antibiotic treatments, there are a number of over the counter remedies for cystitis. These can help relieve the symptoms associated with cystitis like stinging upon urination. 

For relief from inflammation and pain with UTIs, basic pain killers such as ibuprofen and paracetamol may be used. If symptoms persist for more than 48 hours it is recommended to consult a doctor for prescription treatment


Can I take trimethoprim when pregnant?

No, trimethoprim can be harmful to the baby, particularly in the first trimester of pregnancy.

Does trimethoprim need to be taken with food?

Trimethoprim can be taken with or without food. It will have no effect on the effectiveness of the medicine, although taking the medicine with food may assist with lowering stomach upset.

Do I need to finish my trimethoprim course?

Yes, even if you start to feel better after 1-2 days of the 3-day course, complete the course. This is to prevent the infection from coming back if not completely cleared.

Why take trimethoprim at night before bed?

Taking the medicine before sleeping allows it to stay in the bladder longer. This is where the medicine is effective, allowing it to clear the infection faster.

How effective is trimethoprim for UTIs?

Trimethoprim is one of the most common antibiotics prescribed for UTIs. It is usually effective for most cases of uncomplicated UTIs. For more complex infections a doctor may consider alternative treatments.


Info Leaflet

Before using any treatment, you should read the associated information leaflet. You can read the patient information leaflet for Trimethoprim online, at


Warnings and precautions

As with all medicines, there are some patients trimethoprim may not be suitable for. Consult your doctor or pharmacist before you take the medicine if you:

  • Have kidney disease or problems
  • Are pregnant or trying to become pregnant
  • Have a folic acid deficiency
  • Have porphyria
  • Have blood disorders such as hyperkalemia

Trimethoprim may interact with other medicines, it is important when consulting a doctor online or in-person that you inform them of any other medicines you take.

Trimethoprim and alcohol

Drinking alcohol while taking trimethoprim 200mg is considered safe. It is recommended to avoid alcohol if possible as it may worsen cystitis symptoms and cause dehydration.

Trimethoprim in pregnancy and breastfeeding

If you are pregnant or trying to fall pregnant, trimethoprim is not suitable to use. It may cause harm to the baby, particularly during the first trimester. Consult your doctor about your alternative antibiotic options for UTIs while pregnant.

If you are breastfeeding, a small amount of the medicine will pass into the breastmilk, potentially causing side effects in the baby. Consult your doctor before using trimethoprim while breastfeeding.

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Trimethoprim 200mg

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