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Generic Name: trimethoprim
Product Name: Alprim

Indication: What Alprim is used for

Alprim is used to treat infections of the urinary tract caused by bacteria.

Use Alprim only as directed and consult a healthcare professional if pain or symptoms persist.

Ask your doctor if you have any questions about why Alprim has been prescribed for you.

Your doctor may have prescribed Alprim for another reason.

Alprim is available only with a doctor’s prescription.

Alprim is not recommended for use in children under 6 years of age, as the safety and effectiveness of Alprim in this age group have not been established.

Action: How Alprim works

Alprim belongs to a group of medicines called antibiotics. It works by stopping the growth of the bacteria that is causing your infection.

Alprim will not work against infections caused by viruses, such as colds or flu.

The active ingredient in Alprim is trimethoprim. Each Alprim tablet contains 300 mg of trimethoprim.

The tablets also contain the following inactive ingredients lactose, povidone, sodium starch glycollate, purified talc, magnesium stearate.

Dose advice: How to use Alprim

Before you take Alprim

When you must not take it

Do not take Alprim if you are allergic to any other medicines containing trimethoprim or any of the ingredients listed here.

Some of the symptoms of an allergic reaction may include red, itchy skin rashes, itching or hives; swelling of the face, lips or tongue which may cause difficulty in swallowing or breathing; wheezing or shortness of breath.

Do not take Alprim if you have:

  • A severe blood disorder or anaemia;
  • Severe kidney problems.

Do not take Alprim after the expiry date (EXP) printed on the pack.

If you take this medicine after the expiry date, it may not work as well.

Do not take Alprim if the packaging is torn or shows signs of tampering or the tablets do not look quite right.

If you are not sure whether you should start taking this medicine, talk to your doctor.

Before you start to take it

Tell your doctor if you are allergic to any other medicines, foods, dyes or preservatives.

Tell your doctor if you are pregnant or plan to become pregnant.

Alprim is rated in Australia as a Category B3 drug for use in pregnancy. Ask your doctor about the risks and benefits of taking Alprim during pregnancy.

Tell your doctor if you are breastfeeding or wish to breastfeed.

Alprim passes into breast milk and may affect your baby. Alprim is not recommended during breastfeeding.

Tell your doctor if you have, or have had, any medical conditions, especially the following:

  • Folate deficiency;
  • Kidney problems;
  • Liver problems;
  • Any type of blood disorder.

Your doctor may want to take special care if you have any of these conditions.

If you have not told your doctor about any of the above, tell him/ her before you start taking Alprim.

Taking other medicines

Tell your doctor if you are taking any other medicines, including any that you buy without a prescription from a pharmacy, supermarket or health food shop.

Some medicines may be affected by Alprim or may affect how well it works. These include:

  • Pyrimethamine, a medicine used to prevent malaria;
  • Warfarin, a medicine used to prevent blood clots;
  • Methotrexate, a medicine used to treat arthritis and some types of cancer;
  • Phenytoin, a medicine used to control epilepsy (fits or seizures);
  • Digoxin, a medicine used to treat heart failure or to control a fast irregular heartbeat;
  • Procainamide, a medicine used to correct an irregular heartbeat or to slow an overactive heart;
  • Zidovudine, zalcitabine or lamivudine; medicines used for certain viral infections;
  • Dapsone, a medicine used for leprosy or dermatitis herpetiformis;
  • Rifampicin, an antibiotic;
  • Cyclosporin, a medicine used to help prevent organ transplant rejection or to treat certain problems with the immune system;
  • Diuretics, also known as fluid or water tablets;
  • ACE inhibitors, medicines used to treat high blood pressure and some heart conditions.

Your doctor can tell you what to do if you are taking any of these medicines.

If you are not sure whether you are taking any of these medicines, check with your doctor or pharmacist.

This list is not exhaustive. Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking Alprim.

Talk to your doctor about the need for additional contraception while taking Alprim.

Some antibiotics may decrease the effectiveness of some birth control pills.

Tell your doctor or pharmacist that you are taking Alprim before you start taking any other medicine.

How to take Alprim

Follow all directions given to you by your doctor and pharmacist carefully.

They may differ from the information contained here.

If you do not understand the instructions on the pack, ask your doctor or pharmacist.

How much to take

For adults and children over 12 years, the usual dose is one tablet daily.

For children 6 to 12 years, the usual dose is half a tablet daily.

Do not give Alprim to children under the age of 6 years.

There is no information concerning the right dose for children under the age of 6 years.

The elderly and people with kidney problems may need smaller doses.

Different people may respond differently to Alprim, so your doctor may tell you to take a different dose.

Some people may need to take folate supplements while taking Alprim. These people may include the elderly, people with folate deficiency and people taking certain medicines. Your doctor will tell you if this is necessary.

How to take Alprim

Swallow the tablets whole with a glass of water.

When to take Alprim

Alprim can be taken with or without food. Taking Alprim with food will help reduce the chance of a stomach upset.

Alprim tablets are best taken before bedtime.

How long to take Alprim for

Keep taking Alprim until you finish the pack, or for as long as your doctor recommends.

For most infections, Alprim is usually taken for 7 days.

Do not stop taking Alprim, even if you feel better after a few days unless advised by your doctor.

Your infection may not clear completely if you stop taking your medicine too soon.

If you forget to take Alprim

If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take the missed dose as soon as you remember, and then go back to taking your tablets as you would normally.

Do not take a double dose to make up for the dose you missed.

If you are not sure what to do or have any questions, ask your doctor or pharmacist.

If you take too much Alprim (overdose)

Immediately telephone your doctor, or the Poisons Information Centre (telephone 13 11 26), or go to Accident and Emergency at the nearest hospital, if you think you or anyone else may have taken too much Alprim.

Do this even if there are no signs of discomfort or poisoning.

You may need urgent medical attention.

If you take too much Alprim, you may experience the following: nausea, vomiting, dizziness, headaches, confusion or mental depression.

While you are taking Alprim

Things you must do

Immediately stop taking Alprim if skin rash or any other allergic reaction occurs.

Before starting any new medicine, tell your doctor or pharmacist that you are taking Alprim.

Tell all the doctors, dentists and pharmacists who are treating you that you are taking Alprim.

If you become pregnant while taking Alprim, tell your doctor immediately.

If your symptoms do not improve within a few days, or if they become worse, tell your doctor.

If you are taking Alprim for a long time, visit your doctor regularly so that they can check on your progress.

You may need to have regular blood tests.

Always discuss with your doctor any problems or difficulties during or after taking Alprim.

Things you must not do

Do not take any other medicines while you are taking Alprim without first telling your doctor.

Do not drive or operate machinery until you know how Alprim affects you.

Do not use Alprim to treat any other conditions unless your doctor tells you to.

Do not give Alprim to anyone else, even if they have the same condition as you.

After taking Alprim


Keep Alprim where children cannot reach it.

A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.

Keep your tablets in a cool dry place where the temperature stays below 30°C and protect from light.

Do not store Alprim or any other medicine in the bathroom or near a sink.

Do not leave Alprim in the car or on window sills.

Heat and dampness can destroy some medicines.


If your doctor tells you to stop taking Alprim, or your tablets have passed their expiry date, ask your pharmacist what to do with any that are left over.

Schedule of Alprim

Alprim is an S4 (Prescription Only Medicine).

Side effects of Alprim

Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking Alprim.

Alprim helps most people with urinary tract infections, but it may have unwanted side effects in some people.

All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.

Do not be alarmed by this list of possible side effects.

You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor if you notice any of the following and they worry you:

The above list includes the milder side effects of your medicine.

See your doctor immediately if you notice any of the following:

The above list includes serious side effects which may require medical attention.

See your doctor immediately or go to Accident and Emergency at the nearest hospital if you notice any of the following:

  • Signs of an allergic reaction such as itching or hives; swelling of the face, lips or tongue which may cause difficulty in swallowing or breathing; wheezing or shortness of breath;
  • Pink or red itchy spots on the skin which may blister and progress to form raised, red, pale-centred marks;
  • Redness, blistering, peeling or loosening of skin; bleeding of the lips, eyes, mouth, nose, and genitals;
  • Severe rash with skin peeling, fever, chills, and aching muscles.

The side effects listed above are rare but serious and require urgent medical attention or hospitalisation.

Tell your doctor if you notice anything that is making you feel unwell.

This is not a complete list of all possible side effects. Other side effects not listed above may also occur in some people.

Check with your doctor as soon as possible if you have any problems while taking Alprim even if you do not think the problems are connected with the medicine or are not listed here.

For further information talk to your doctor.


  1. Alprim Consumer Medicine Information (CMI). Millers Point, NSW: Alphapharm Pty Ltd. August 2013. [PDF]
  2. Alprim Product Information (PI). Millers Point, NSW: Alphapharm Pty Ltd. October 2016. [PDF]

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Posted On: 22 July, 2003
Modified On: 30 October, 2017
Reviewed On: 12 October, 2017

Created by: myVMC