Trimethoprim

Buy Trimethoprim 200mg treatment for cystitis online from Dr Fox - for recurring infection. Be prepared with a standby antibiotic to keep for when needed.

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About Trimethoprim

General information about cystitis and standby treatment, and selecting the right antibiotic, can be found at the cystitis medical information page. The information below is about trimethoprim. There is a separate page about nitrofurantoin, which is the alternative antibiotic Dr Fox supplies for cystitis. Please also read the manufacturer's patient leaflet supplied with trimethoprim tablets.

Trimethoprim is an antibiotic commonly used to treat uncomplicated cystitis. In the past decade antibiotic resistance to trimethoprim has increased. About 30% of the bacteria which cause cystitis are now resistant to trimethoprim and it is no longer the first choice antibiotic in general practice. The antibiotic nitrofurantoin is now usually more effective and is usually the first choice, although trimethoprim is still widely prescribed and many women find it effective and prefer it.

For further information see NHS - trimethoprim.

Taking trimethoprim

Trimethoprim 200mg twice daily for 3 days is usually effective for cystitis. Improvement is usually seen within 24 hours and symptoms are usually completely resolved after 3 days.

Cautions and contraindications

Trimethoprim is not suitable for everyone. Patients with some medical conditions or who are taking interacting medicines cannot take it. Checks for suitability are carried out in the online consultation which is part of the ordering process.

DO NOT take trimethoprim tablets if the following apply unless discussed with your regular doctor beforehand.

• You are allergic (hypersensitive) to trimethoprim or to any of the other ingredient.
• You are pregnant or breastfeeding.
• Suffer from severe kidney or liver problems.
• Suffer from any blood disorders such as anaemia.

Talk to your doctor or pharmacist before taking trimethoprim tablets if you:

• Are pregnant.
• Suffer from kidney problems/kidney disease or are having dialysis treatment.
• Have a deficiency (are low) in folic acid (may cause anaemia).
• Are at greater risk of high levels of potassium in your blood (hyperkalaemia), e.g. the elderly or those on higher doses
• Are also taking repaglinide (medicine for treating diabetes).
• Suffer from porphyria (a disorder that causes skin sensitivity to light, pain attacks and muscle weakness).

Interactions

Trimethoprim should not be taken with the following medicines without the advice of a doctor who knows you.

• Repaglinide, used to treat diabetes.
• Procainamide, to treat abnormal heart rhythm.
• Digoxin, to treat certain heart conditions.
• Diuretics (e.g. water tablets such as frusemide or eplerenone).
• Rifampicin (antibiotic), used to treat TB.
• Anticoagulants (to prevent clots from forming in the blood e.g. warfarin).
• Phenytoin, to treat epilepsy.
• Pyrimethamine and dapsone, used to treat malaria.
• Immunosuppressant drugs - used in cancer treatment (e.g. methotrexate) or to treat organ rejection after transplant (e.g. azathioprine or ciclosporin).
• Bone marrow depressants.
• Spironolactone.

Side effects and severe reactions

Allergic reactions

Very occasionally a first dose of trimethoprim will trigger a severe allergic reaction, which is a medical emergency requiring emergency medical care. STOP taking Trimethoprim tablets and contact your doctor or go to your nearest hospital casualty department IMMEDIATELY if you notice any of the following symptoms:

• Difficulty breathing.
• Swelling of the face, lips, tongue and throat.
• Chest pain.
• Shock, fainting or collapse.
• Blistering/peeling of the skin.
• Pancreatitis (signs may include a sudden, severe upper abdominal pain).
• Skin eruptions/lesions.
• Deep swelling of the skin (angioedema).

Side effects (non-emergency)

As with any medicine side effects may occur although most patients do not experience them, or they may be mild and treatment does not always need to be stopped. The side effects listed below are not medical emergencies, but may require medical advice.

Common (may affect up to 1 in 10 people):

• Feeling and being sick, diarrhoea.
• Headache.
• Skin rashes.
• Urticaria (hives).
• Anaemia (may cause you to feel tired and look pale).
• Sore throats or mouth ulcers (due to a decrease in white blood cells).
• Thrush.

Very rare (may affect up to 1 in 10,000 people):

• Constipation, severe watery/bloody diarrhoea
• Cough
• Agitation
• Abnormal behaviour
• Aseptic meningitis can occur in some patients. This may show as a combination of symptoms such as headache, fever, stiff neck, tiredness, feeling ill, and your eyes become very sensitive to bright light.
• Jaundice (yellowing of the skin or whites of the eyes).
• Kidney problems (signs may include painful urination or blood in the urine).
• Dizziness, tiredness.
• Convulsions.
• Involuntary movements.
• Pins and needles, shakiness, tremors.
• Ringing in the ears, vertigo.
• Eye redness and pain.
• Increased sensitivity of the skin to the sun.
• Low blood sugar.
• Low levels of sodium in the blood (may cause nausea, tiredness, muscle cramping).
• Anorexia.
• Depression, anxiety, sleeping difficulties, and nightmares.
• Confusion, hallucinations.
• Elevation of serum transaminases, (an indication of liver damage).
• Elevation of bilirubin levels.
• Joint and muscle ache.
• Shortness of breath, wheezing, nosebleeds.
• Meningitis (signs may include stiff neck, fever and vomiting).
• Lupus erythematosus (an auto-immune disorder).
• Purple discolourations of the skin.
• Fever.
• Reduction in numbers of blood cells.
• Anaemia.

Unknown (frequency cannot be estimated):

• Sore tongue and mouth.
• Gastrointestinal disturbances.
• Pruritus (itching).
• Elevation of serum creatinine and blood urea nitrogen levels.

Pregnancy and breast-feeding

If you are pregnant or breast-feeding, think you may be pregnant or a planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine. Trimethoprim should not be used in pregnancy. DO NOT take trimethoprim tablets if you are pregnant. If you are breast-feeding, ask your doctor or pharmacist for advice before taking this medicine.

Patient Information Leaflet

The Patient Information Leaflet (PIL) is the leaflet included in the pack with a medicine and must be read before taking the medicine. It is written for patients and gives information about taking or using a medicine.

Trimethoprim patient leaflet

Authored 18 February 2010 by Dr Tony Steele
MB ChB Sheffield University 1983. Former hospital doctor and GP.

Reviewed by Dr B. Babor, Dr A. Wood, Dr P. Hunt
Last reviewed 01 March 2019
Last updated 18 October 2021