Trimethoprim - oral

Patient Medicine Information
Why do I need this medicine?
Trimethoprim is an antibiotic. It is used on its own or together with other medicines to treat certain bacterial infections of the urinary tract, lungs, ears and stomach.
How do I take this medicine?
Take Trimethoprim exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.

This medicine is best taken with food to minimise any stomach discomfort that it may cause. Try to take it same time each day.

Take Trimethoprim at regular intervals as instructed. Do not skip any doses. Continue to take it even when you feel better. You must complete the entire course of antibiotic. If you don't, the infection will not clear completely.
What should I do if I have forgotten to take this medicine?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.

DO NOT double a dose under any circumstances.

If you often forget to take your medicine, let your doctor and pharmacist know.
When should I not use this medicine?
Alert your doctor if you have a blood disorder known as megaloblastic anaemia caused by folic acid deficiency as Trimethoprim may not be suitable for you.
What should I take note of while using this medicine?
Inform your doctor if you have kidney or liver disease.

Let your doctor know if you are pregnant or breastfeeding.

For as long as you are taking this medicine, you may need to have regular blood tests to check your body’s response to Trimethoprim. Your doctor will advise you about how often you need to have blood tests.
What side effects could I experience?
Trimethoprim may cause any of the following side effects: headache, rash, itch, nausea, stomach discomfort and vomiting.

Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Can I take this with other medicines?
Inform your doctor and pharmacist if you are taking any of these medicines:

- medicines for epilepsy (fits or seizures) e.g. phenytoin
- medicines used in organ transplant or certain immune disorders e.g. azathioprine, mercaptopurine
- pyrimethamine (medicine for malaria)
- medicines for heart disease e.g. digoxin, procainamide,
- antibiotic e.g. rifampicin, dapsone,
- water pills e.g. hydrochlorothiazide
- medicines for diabetes e.g. repaglinide
- blood-thinning medicines e.g. warfarin

This list does not include all medicines that may interact with Trimethoprim.

Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
What special dietary instructions should I follow?
Avoid alcohol.
How should I store this medicine?
Store in a cool, dry place away from the reach of children.

Medicines must not be used past the expiry date.
This information is independently developed by MIMS based on trimethoprim - oral and is provided for your reference only. It is not a replacement for and should only be used in conjunction with full consultation with a licensed healthcare professional, the information provided by your pharmacist and/or the manufacturer of the medication. It may not contain all the available information you require and cannot substitute professional medical care, nor does it take into account all individual circumstances. Although great effort has been made to ensure content accuracy, we shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2021 MIMS. All rights reserved. Powered by
  • Trimethop
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Sign up for free
Already a member? Sign in