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Trimethoprim 200mg tablets are one of the two first-choice antibiotics for cystitis and other uncomplicated UTIs in UK guidance. For women aged 18 to 64, prescribed after an online consultation with a GPhC-registered pharmacist independent prescriber.
Order before 3pm — same-day dispatch (MON - FRI)
~5 min consultation
Secure & confidential · Reviewed by a UK prescriber
Suitable age
18 Years +
Max per order
1 pack
Consultation
✓ Yes — online consultation
Trimethoprim is an antibiotic used to treat cystitis, the most common type of urinary tract infection (UTI) in women. It stops the bacteria that cause most UTIs, such as E. coli, from making folic acid, which they need to grow and multiply. NICE recommends it, alongside nitrofurantoin, as a first choice for women with cystitis, as long as the risk of resistance is low. That’s why we ask whether you’ve taken it recently.
The usual course is one 200mg tablet twice a day for 3 days. Our trimethoprim guide explains how it works and how quickly it starts to help, and our guide to trimethoprim side effects covers what to expect. To compare it with other options, see UTI antibiotics in the UK or our cystitis treatment online page.
| Medicine type | Antibiotic |
| Active ingredient | Trimethoprim 200mg |
| Recommended use | Cystitis (uncomplicated lower urinary tract infection) in women |
| Course length | Usually 3 days (6 tablets); 7 days (14 tablets) only if your prescriber decides it’s needed |
| Prescription status | Prescription Only Medicine (POM) |
| Dosing | One tablet twice a day, with or without food |
| Suitable for | Women aged 18 to 64, not pregnant or breastfeeding |
| Generic available | Yes - generic trimethoprim 200mg tablets |
| UK guidance | NICE NG109 (first choice, if resistance risk is low) |
| Prescription status | Prescription-only medicine (POM) |
Trimethoprim may be suitable if you: - are a woman aged 18 to 64; - have typical cystitis symptoms: burning when you pee, needing to pee often or urgently, or pain low in your tummy; - haven’t taken trimethoprim in the last 3 months; - aren’t pregnant or breastfeeding.
This service isn’t suitable if you: - are a man, under 18 or aged 65 or over; - are pregnant, might be pregnant, or are breastfeeding; - have back or side pain, a high temperature, shivering or vomiting (signs of a kidney infection); - can see blood in your urine; - have had 2 urine infections in the last 6 months, or 3 in the last year. Your GP can arrange a urine culture; - have a catheter, a weakened immune system, or severe kidney or liver disease; - have unusual vaginal discharge or itching, which may be thrush or an STI.
Tell the prescriber if you: - have kidney problems, diabetes, a blood disorder, low folate or porphyria; - take any of these medicines: - methotrexate; - warfarin; - phenytoin; - digoxin; - ciclosporin; - azathioprine; - repaglinide; - medicines that raise potassium, such as ACE inhibitors (for example ramipril), ARBs (for example losartan), spironolactone, potassium supplements or salt substitutes.
If trimethoprim isn’t right for you, nitrofurantoin is the other first-choice antibiotic. See our nitrofurantoin guide.
Trimethoprim is a prescription antibiotic. It blocks an enzyme that bacteria need to make folic acid, so they can’t grow and multiply, and your body can clear the infection. It’s one of the two first-choice antibiotics for cystitis in women in UK guidance. Our trimethoprim guide explains more.
Many women start to feel better within a day or two. Keep taking it for the full course, even if you feel better sooner. If your symptoms haven’t started to improve within 48 hours, or they get worse, contact your GP or NHS 111, as you may need a urine test and a different antibiotic.
Take one 200mg tablet twice a day, about 12 hours apart, with a glass of water. You can take it with or without food. The usual course for cystitis is 3 days. Your prescriber may give a 7-day course if it’s needed, and you should finish whichever course you’re given.
The most common are feeling sick, diarrhoea, headache, itching, a mild rash and thrush. It can also raise potassium levels, which matters if you take certain heart or blood pressure medicines. Stop taking it and get urgent help for a severe or blistering rash, swelling of the face or throat, unusual bruising or bleeding, or a fever with a sore throat. See our trimethoprim side effects guide.
Alcohol doesn’t stop trimethoprim working, but it can irritate the bladder, make cystitis symptoms worse and add to sickness. It’s best to avoid it, or keep it to a minimum, until you’ve finished the course and feel better.
No. Trimethoprim doesn’t reduce the effect of the combined pill, the mini pill or other hormonal contraception. If you’re sick or have severe diarrhoea, the pill may not be absorbed properly. In that case, follow the missed-pill advice in your pill’s leaflet.
Not through our online service. Trimethoprim must not be used in the first 3 months of pregnancy, and urine infections in pregnancy need a urine test and a specific treatment plan. Please contact your GP or midwife the same day. If you’re breastfeeding, see your GP or a pharmacist.
Trimethoprim comes in two packs: 6 tablets (a 3-day course, £12.99) and 14 tablets (a 7-day course, £16.99). The 3-day course is the usual treatment for cystitis in women, as UK guidance recommends. The prescriber supplies the 14-tablet pack if they decide a longer course is needed, so you don’t need to choose: just complete the consultation and they’ll pick the right course.
Both are first-choice antibiotics in UK guidance and work well. Nitrofurantoin is often preferred because resistance to it is less common, but it isn’t suitable if your kidneys don’t work well. Trimethoprim is a good choice if you haven’t taken it in the last 3 months. Our UTI antibiotics guide compares them.
Yes. Like other antibiotics, it can upset the natural balance of the vagina and trigger thrush in some women. If you get itching and thick white discharge during or after the course, a pharmacist can recommend an antifungal treatment. See our guide to thrush after antibiotics.
Helpful articles and clinical guides related to this treatment category.
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