Trimethoprim for bacterial infections
This leaflet is about the use of the antibiotic trimethoprim
for the treatment of infections.
If your child has ever had a reaction to any antibiotic, check with your doctor that your child can have trimethoprim, before giving it.
This leaflet has been written specifically about the use of this medicine in children. The information may differ from that provided by the manufacturer. Please read this leaflet carefully. Keep it somewhere safe so that you can read it again.
Name of drug
Trimethoprim
Common brands: Trimopan®, Proloprim®, Monotrim®
Why is it important for my child to take this medicine?
It is important that your child takes this medicine in the way that your doctor has told you to so that it kills all the bacteria and gets rid of the infection.
What is trimethoprim available as?
- Tablets: 100 mg, 200 mg
- Liquid medicine (suspension): 50 mg in 5 mL
When should I give trimethoprim?
Trimethoprim is usually given twice each day, once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example some time between 7 and 8 am, and between 7 and 8 pm.
Sometimes trimethoprim is given once a day to prevent infections.
How much should I give?
Your doctor will work out the amount of trimethoprim (the dose) that is right for your child. The dose will be shown on the medicine label.
- It is important that you follow your doctor’s instructions about how much to give.
How should I give trimethoprim?
This medicine works best when the stomach is empty, so try to give it to your child ½–1 hour before they eat. However, if your child has an upset stomach, you can give it with a small amount of food.
 | Tablets should be swallowed with a glass of water, milk or juice. Your child should not chew tablets. |
 | Liquid Medicine: Shake the medicine well. Measure out the right amount using a medicine spoon or oral syringe. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount. You can also dilute the right amount of medicine (measured with a spoon) in a small amount of water or milk. Make sure your child takes it all straight away. |
- It is important that you give your child the whole dose each time.
When should the medicine start working?
Your child should start to get better after taking the medicine for 2 days. It is important that they take the whole course of medicine that has been prescribed. Do not stop early.
What if my child is sick (vomits)?
- If your child is sick less than 30 minutes after having a dose of trimethoprim, give them the same dose again.
- If your child is sick more than 30 minutes after having a dose of trimethoprim, you do not need to give them another dose. Wait until the next normal dose.
What if I forget to give it?
If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7 am, you can give the missed dose at any time up to 11 am. If you remember after that time, do not give the missed dose. Wait until the next normal dose. Do not give any extra to make up for the missed dose.
Never give a double dose of trimethoprim.
What if I give too much?
Trimethoprim is normally a safe drug. It is unlikely to cause any problems if you give an extra dose by mistake.
If you think you may have given your child too much trimethoprim, contact your doctor or NHS Direct (0845 4647). Have the medicine container or packet with you if you telephone for advice.
Are there any possible side-effects?
We use medicines to make our children better, but sometimes they have other effects that we don’t want (side-effects).
Side-effects are rare with trimethoprim and do not usually last for long. They will get better after a day or two as your child’s body gets used to the medicine, and should go away when the treatment course is finished.
Side-effects that you must do something about
- If you child gets a skin rash or itching, has problems breathing or seems short of breath or is wheezing, or if their face, throat, lips or tongue start to swell, they may be allergic to trimethoprim. Take them to hospital or call an ambulance straight away.
- If your child has a bad skin rash, or itchy, peeling or blistering skin, contact your doctor straight away, as this may need treatment in hospital. Do not give your child any more trimethoprim.
Other side-effects you need to know about
- Your child may get diarrhoea, stomach pains and may feel sick or be sick (vomit) and may not feel like eating. The box overleaf gives advice about what to do.
- Contact your doctor if your child has diarrhoea that goes on for more than 4 days or if it is severe and watery, or contains blood.
Other side-effects you need to know about
- This medicine can make your child’s skin more sensitive to sunlight. Avoid bright sunlight and protect your child’s skin with clothes and high-factor sun cream.
Important things to know about taking antibiotics
- It is vital that your child completes the course of antibiotic. This means that they must take the medicine for the number of days that the doctor has told you, or until all the tablets or capsules have been taken. Your child will probably start to feel better soon after starting to take the antibiotic. However, it takes a few days for the antibiotic to kill all the bacteria. If you stop giving the antibiotic too soon, the bacteria that are left will start to multiply again, and may cause another infection. There is also a risk that these bacteria will be ‘resistant’ to the first antibiotic. This means that it might not work next time, and your child might need a stronger antibiotic.
- Children are sometimes sick (vomit) or get diarrhoea when taking antibiotics. Encourage them to drink water to replace the fluid they have lost. You can also buy oral rehydration fluid from your pharmacist.
- Do not give your child any medicine to stop the diarrhoea unless your doctor has told you to, as this can make things worse.
- Try to give the medicine at about the same times each day, to help you remember, and to make sure that there is the right amount of medicine in your child’s body to kill the bacteria.
- Only give this medicine to your child for their current infection.
- Never save medicine for future illnesses. Throw away any unused medicine or return it to the pharmacist.
- Only give the antibiotic to the child for whom it was prescribed. Never give it to anyone else, even if their condition appears to be the same, as this could do harm.
- If you think someone else may have taken the medicine by accident, contact your doctor for advice.
- Antibiotics only kill bacteria; they do not kill viruses. This means that they do not work against colds, sore throats, flu or other infections that are caused by viruses. Your doctor will not prescribe antibiotics for these illnesses.
Can other medicines be given at the same time as trimethoprim?
- You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
- Trimethoprim should not be taken with some common drugs that you get on prescription. If your child is taking any other drugs, tell your doctor and pharmacist.
- Check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal or complementary medicines.
Where should I keep this medicine?
- Keep the medicine in a cupboard, away from heat and direct sunlight.
- You may need to keep liquid medicine in the fridge – check the instructions on the bottle. Make sure that the medicine doesn’t freeze.
- Make sure that children cannot see or reach the medicine.
- Keep the medicine in the container it came in.
