Triméthoprime pour les infections
Révision par Sid DajaniDernière mise à jour par Michael Stewart, MRPharmSDernière mise à jour le 5 mai 2025
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Trimethoprim is an antibacterial medicine prescribed for treating infections, mainly chest or urine infections. It is sometimes prescribed to prevent an infection.
Space out your doses evenly throughout the day, and remember to finish the full course of treatment.
The most common side-effects are feeling sick (nausea), and a mild itchy rash.
Dans cet article :
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About trimethoprim
Type de médicament | Un médicament antibactérien |
Utilisé pour | Bacterial infections (in adults and children) |
Disponible en | Comprimés et médicaments liquides oraux |
Trimethoprim is given to treat a bacterial infection. It is mainly prescribed for urine infections, but it is also prescribed for chest infections and some other types of infection. It works by killing the germs (bacteria) responsible for the infection.
A urine infection is often called a urinary tract infection (UTI) by doctors. Most urine infections are caused by bacteria that come from your own bowel. They are usually easily treated with a short course of trimethoprim. Occasionally, longer-term treatment may be needed to prevent the infection from recurring.
Before taking trimethoprim
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking trimethoprim it is important that your doctor knows:
Si vous êtes enceinte, si vous essayez d'avoir un enfant ou si vous allaitez.
If you know you have low amounts of the vitamin folic acid.
Si vous avez des problèmes de fonctionnement des reins.
Si vous avez des problèmes de fonctionnement du foie.
If you have a blood disorder, or if you have a rare inherited blood disorder called porphyria.
Si vous prenez d'autres médicaments. Cela inclut tous les médicaments disponibles sans ordonnance, ainsi que les médicaments à base de plantes et les médicaments complémentaires.
Si vous avez déjà eu une réaction allergique à un médicament.
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How to take trimethoprim
Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about trimethoprim and will provide you with a full list of the side-effects which you could experience from taking it.
Take trimethoprim tablets exactly as your doctor tells you to. Your dose will depend upon whether you are being treated because you have an infection, or to prevent an infection. As a guide, the dose for adults with an infection is 200 mg twice daily, taken morning and evening. The adult dose to prevent an infection is 100 mg at night. If trimethoprim has been prescribed for a child, it is likely that you will be supplied a liquid medicine - the dose will depend upon the age of the child, so read the directions on the label carefully to make sure you give the correct dose.
Space your doses out evenly throughout the day - this means that tablets/medicine prescribed twice daily should be taken every 12 hours. Swallow the tablet with a drink of water. You can take trimethoprim either with or without food.
Even if you feel your infection has cleared up, keep taking trimethoprim until the full course is finished (unless a doctor tells you to stop). This is to prevent the infection from coming back. A normal course of treatment is likely to last 3-14 days. The course will be for longer than this if you are taking trimethoprim to prevent recurrent infections.
If you forget to take a dose at the correct time, take one as soon as you remember. Try to take the correct number of doses each day. Do not take two doses at the same time to make up for a forgotten dose.
Tirer le meilleur parti de votre traitement
Most people improve within a few days of starting treatment. If your symptoms do not improve despite taking trimethoprim, go back to see your doctor, as you may need an alternative medicine. This is because some bacteria are resistant to some types of antibiotics.
If you are taking the contraceptive 'pill' at the same time as this antibacterial medicine, the effectiveness of the 'pill' can be reduced if you have a bout of being sick (vomiting) or diarrhoea which lasts for more than 24 hours. If this should happen, ask your doctor or pharmacist for advice about what additional contraceptive precautions to use over the following few days. There is no need to use additional precautions for any bouts of sickness or diarrhoea which last for less than 24 hours.
Trimethoprim can stop the oral typhoid vaccine from working. If you are due to have any vaccinations, make sure the person treating you knows that you are taking it.
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Can trimethoprim cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with trimethoprim. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
Very common trimethoprim side-effects (these affect more than 1 in 10 people) | Que puis-je faire si je suis confronté à cette situation ? |
Se sentir malade (nausées) ou être malade (vomissements) | Stick to simple foods - avoid fatty or spicy meals. If you are not already doing so, try taking trimethoprim after food |
Common trimethoprim side-effects (these affect fewer than 1 in 10 people) | Que puis-je faire si je suis confronté à cette situation ? |
Diarrhée | Drink plenty of water to replace lost fluids. Stick to simple foods |
Maux de tête | Buvez beaucoup d'eau et demandez à votre pharmacien de vous recommander un analgésique adapté. Si les maux de tête persistent, prévenez votre médecin |
Éruption cutanée avec démangeaisons | Try applying a gentle, fragrance-free skin moisturiser. If the rash becomes troublesome or severe, speak with your doctor |
Important: if trimethoprim is taken over a long period of time (such as when it is taken long-term to prevent an infection), it can occasionally cause problems. If you develop a high temperature (fever), sore throat, skin rash, mouth ulcers or any bruising or bleeding which you can't explain, you should let your doctor know about this straightaway. These may be signs of a blood disorder.
Si vous ressentez d'autres symptômes qui pourraient être dus à ce médicament, parlez-en à votre médecin ou à votre pharmacien.
How to store trimethoprim
Conservez tous les médicaments hors de la portée et de la vue des enfants.
Conserver dans un endroit frais et sec, à l'abri de la chaleur et de la lumière directes.
Informations importantes sur tous les médicaments
Informations importantes sur tous les médicaments
Ne dépassez jamais la dose prescrite. Si vous pensez que vous ou quelqu'un d'autre avez pris une dose excessive de ce médicament, rendez-vous immédiatement au service des accidents et des urgences de votre hôpital local. Emportez la boîte avec vous, même si elle est vide.
Ce médicament est pour vous. Ne le donnez jamais à d'autres personnes, même si leur état semble être le même que le vôtre.
Si vous achetez des médicaments, vérifiez auprès d'un pharmacien qu'ils peuvent être pris en même temps que vos autres médicaments.
Si vous devez subir une opération ou un traitement dentaire, indiquez à la personne chargée du traitement les médicaments que vous prenez.
Ne gardez pas les médicaments périmés ou dont vous ne voulez plus. Apportez-les à votre pharmacie locale qui les éliminera pour vous.
Si vous avez des questions sur ce médicament, demandez à votre pharmacien.
Signaler les effets secondaires d'un médicament ou d'un vaccin
Si vous ressentez des effets secondaires, vous pouvez les signaler en ligne sur le site web de la carte jaune.
Autres lectures et références
- Manufacturer's PIL, Trimethoprim 50 mg/5 ml Suspension; Pinewood Healthcare, The electronic Medicines Compendium. Dated June 2019.
- Médicaments Complet BNF 89ème éditionBritish Medical Association et Royal Pharmaceutical Society of Great Britain, Londres.
Historique de l'article
Les informations contenues dans cette page sont rédigées et évaluées par des cliniciens qualifiés.
Prochaine révision prévue : 5 mai 2028
5 mai 2025 | Dernière version

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