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Trimetoprim för infektioner

Granskad av Sid DajaniSenast uppdaterad av Michael Stewart, MRPharmSSenast uppdaterad 5 May 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.

Överblick

  • Trimethoprim is an antibacterial medicine used to treat bacterial infections.

  • It is mainly prescribed for urine infections, but also for chest infections and other types.

  • Take trimethoprim exactly as your doctor tells you, usually for 3-14 days.

  • It can be taken with or without food, and is available as tablets or oral liquid medicine.

  • If you develop a high temperature, sore throat, or unusual bruising, contact your doctor immediately.

Denna sammanfattning har automatiskt genererats från artikelns innehåll för att hjälpa läsarna att snabbt förstå huvudpunkterna.

About trimethoprim

Typ av medicin

An antibacterial medicine

Används för

Bacterial infections (in adults and children)

Tillgänglig som

Tabletter och flytande medicin för oral användning

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:

  • Om du är gravid, försöker bli gravid eller ammar.

  • If you know you have low amounts of the vitamin folic acid.

  • If you have problems with the way your kidneys work.

  • If you have problems with the way your liver works.

  • If you have a blood disorder, or if you have a rare inherited blood disorder called porphyria.

  • Om du tar några andra läkemedel. Detta inkluderar alla läkemedel som kan köpas utan recept, samt växtbaserade och komplementära läkemedel.

  • Om du någonsin har haft en allergisk reaktion mot en medicin.

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.

Få ut det mesta av din behandling

  • 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.

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)

Vad kan jag göra om jag upplever detta?

Feeling sick (nausea) or being sick (vomiting)

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)

Vad kan jag göra om jag upplever detta?

Diarré

Drink plenty of water to replace lost fluids. Stick to simple foods

Huvudvärk

Drick mycket vatten och be din apotekare rekommendera en lämplig smärtstillande. Om huvudvärken fortsätter, informera din läkare

Itchy skin rash

Try applying a gentle, fragrance-free skin moisturiser. If the rash becomes troublesome or severe, speak with your doctor

Viktigt: 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.

Om du upplever några andra symtom som du tror kan bero på denna medicin, tala med din läkare eller apotekare.

How to store trimethoprim

  • Förvara alla läkemedel utom räckhåll och synhåll för barn.

  • Förvara på en sval, torr plats, borta från direkt värme och ljus.

Viktig information om alla läkemedel

Viktig information om alla läkemedel

Ta aldrig mer än den föreskrivna dosen. Om du misstänker att du eller någon annan kan ha tagit en överdos av denna medicin, gå omedelbart till akutmottagningen på ditt lokala sjukhus. Ta med behållaren, även om den är tom.

Denna medicin är för dig. Ge den aldrig till andra människor även om deras tillstånd verkar vara detsamma som ditt.

Om du köper några mediciner, kontrollera med en apotekare att de är säkra att ta tillsammans med dina andra mediciner.

Om du ska genomgå en operation eller någon tandbehandling, informera den som utför behandlingen om vilka mediciner du tar.

Behåll inte föråldrade eller oönskade mediciner. Ta dem till ditt lokala apotek som kommer att ta hand om dem åt dig.

Om du har några frågor om denna medicin, fråga din apotekare.

Rapportera biverkningar av ett läkemedel eller vaccin

Om du upplever biverkningar kan du rapportera dem online via Yellow Card webbplats.

symptomkontroll

Osäker på att blanda mediciner?

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Vanliga frågor

Can trimethoprim be used for conditions other than urine infections?

Yes, while trimethoprim is mainly prescribed for urine infections (also known as UTIs), it can also be prescribed for chest infections and certain other types of bacterial infections.

How long does a typical course of trimethoprim treatment last?

A normal course of treatment for an infection is likely to last between 3 and 14 days. If you are taking trimethoprim to prevent recurrent infections, the course will be longer than this.

What should I do if my symptoms don't improve after starting trimethoprim?

If your symptoms do not improve within a few days of starting treatment, you should go back to see your doctor. This is important because you might need an alternative medicine, as some bacteria can be resistant to certain types of antibiotics.

Why is it important to complete the entire course of trimethoprim even if I feel better?

Even if you feel your infection has cleared up, it's crucial to keep taking trimethoprim until the full course is finished, unless your doctor tells you to stop. This is done to prevent the infection from returning.

Are there any specific symptoms I should watch out for if I'm taking trimethoprim for a long time?

If you are taking trimethoprim over a long period, you should be aware that it can occasionally cause problems. If you develop a high temperature (fever), a sore throat, a skin rash, mouth ulcers, or any unexplained bruising or bleeding, you should contact your doctor straight away. These could be signs of a blood disorder.

Dessa frågor och svar har genererats från informationen i denna artikel.

Vidare läsning och referenser

Om författarenVisa fullständig biografi

Författarbild

Michael Stewart, MRPharmS

Ansvarig för granskning av medicinbroschyrer – Konsult, Apotekare

BPharm (Hons), MRPharmS

Michael är en apotekare som arbetar i Midlands och South Yorkshire med mer än 20 års erfarenhet av att ge råd om läkemedel och medicinska tillstånd. Han har en stark bakgrund inom vårdutbildning och har producerat och levererat utbildningskurser för apoteksteam och personal inom vårdboenden, inklusive sjuksköterskor. Han har också bidragit till apoteksrådgivande styrelser för hantering av mindre allvarliga tillstånd i samhället.

Om recensenten

Författarbild

Sid Dajani

Sultan Dajani tog examen vid London School of Pharmacy 1994 och blev den yngsta valda medlemmen i Royal Pharmaceutical Society-rådet sedan dess grundande 1842.

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