Trimethoprim is a broad use antibiotic, which comes in tablet format. It can be used to treat a wide range of bacterial infections and is often used to treat cystitis, a common UTI.
Cystitis is an infection which causes inflammation of the bladder that is generally caused by bacteria. It mostly affects women, with about half suffering from this at some point in their lives, but it can also affect men (it’s a lot less common though). It can clear up on its own but for persistent and severe symptoms it may require antibiotics, such as Trimethoprim.
How does Trimethoprim work?
Trimethoprim is a type of antibiotic which prevents the growth of bacteria. Bacteria requires the substance folate in order to grow. Trimethoprim stops bacteria from producing folate, and this prevents the bacterial cells from duplicating themselves as they cannot produce DNA.
Because the bacteria can no longer grow and increase in number, this allows the body’s own immune system to clear up the remaining infection by destroying any infection that’s left.
What doses of Trimethoprim are there?
Trimethoprim can be supplied in two doses, either 100mg or 200mg. Any dosage prescribed will depend on the severity and nature of your symptoms, together with your age and how well your kidneys work.
How to take Trimethoprim
For instructions on specific dosages, you should always refer to the package information leaflet or the advice of your clinician. Please note Trimethoprim is not suitable for children under 6.
Usually, your doses will be as follows:
For 100mg tablets:
Women: two tablets, twice daily for 3 days.
Men: two tablets, twice daily for 7 days.
For oral solution:
Women: Take four 5ml spoonfuls twice daily for 3 days.
Men: Take four 5ml spoonfuls twice daily for 7 days.
How long does it take Trimethoprim to work?
If it’s taken correctly, you should see an improvement in your symptoms within 24 hours, and your infection should continue to clear up during the remaining course of your Trimethoprim. But if you see no improvement after the initial 48 hours of starting your medication, you should send our clinician a message and speak to them about the next steps.
An important factor is to always continue the course of treatment as advised, even if you start to feel better before it’s finished. Although it may appear that the treatment has fully worked, there may be some residual bacteria remaining, which can become resistant to the antibiotic and cause problems further down the line.
What should I do if I make a mistake when taking Trimethoprim?
As with all medications, in order for them to have the desired effect they should be taken in the prescribed quantities and at the prescribed times given. If for some reason a dose is accidently missed at the correct time, then it can be taken when remembered as long as it is not too close to your next dose. If it is, then that dose should be missed and taken at the end of the full course. Never attempt to ‘double up’ on doses to make up for a missed dose.
If your day to day activities keep you very busy, it may be helpful to set an alarm on your phone or alarm clock to remind you to take your medication.
If you take too much Trimethoprim, you should seek medical assistance immediately.
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How is Trimethoprim different from other treatments for cystitis?
Trimethoprim is not generally used as a first line of defense for cystitis as resistance to it has been shown to be increasing, so other antibiotics such as MacroBID and Nitrofurantoin are often prescribed at the onset of symptoms.
If these are not suitable, then Trimethoprim may be prescribed initially. Examples of this could be where there is a known allergy to them or they have been previously prescribed and proven ineffective.
Is Trimethoprim similar to any other treatments?
There are other treatments available which use the active ingredient Trimethoprim that will work in a similar way. But they may come in a different form, with different packaging, and be manufactured by different pharmaceutical companies.
Which dose of Trimethoprim should I use?
Our clinician will prescribe a dosage according to the severity of your symptoms, and take your gender into account when deciding on the quantity and duration of your treatment. Age will also be a key consideration along with your general health condition, particularly anything relating to kidney function. For children aged 6 -12 a lower dosage will normally be suggested.
Do I need a prescription for Trimethoprim?
As with all other antibiotics, Trimethoprim is no different and requires a prescription, so that our clinician can ensure it’s safe and suitable for you to use. Your gender, age and any underlying health conditions can also factor into whether it’s an appropriate treatment for you.
Why should I buy Trimethoprim online with Treated?
Your health, wellbeing and happiness is at the forefront of everything we do here at Treated. That means empowering you to take control of your own healthcare and make the right choice for you. We’ll recommend the right medications for you, and you can choose which option you’d like from there.
Once you receive your chosen treatment, a member of our clinical team will get in touch to check in with you and make sure your medication is working the way that it should.
Why did some practices not implement new antibiotic prescribing guidelines on urinary tract infection? A cohort study and survey in NHS England primary care. The Journal of antimicrobial chemotherapy, 74(4), 1125–1132.
Disclaimer: The information provided on this page is not a substitute for professional medical advice, diagnosis, or treatment. If you have any questions or concerns about your health, please talk to a doctor.
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