Explanation

Co-trimoxazole (also called Setrin®) is a medicine that helps your body to fight infections.

It is used to fight all sorts of infections all around your body, including lung, bladder, ear and skin infections.

How does it work?

Co-trimoxazole is a type of medicine called an antibiotic. It actually contains TWO antibiotics! One is called sulfamethoxazole and the other is called trimethoprim.

These two antibiotics work by stopping bacteria from multiplying. This gives your immune system help to fight off infections caused by bacteria.

What does it look like?

Co-trimoxazole comes as a small white tablet that you swallow with a glass of water.

It also comes as a liquid for very young children, or if you find it hard to swallow tablets. You swallow the liquid from a spoon that comes with it.

If you are in hospital, you may also be given co-trimoxazole intravenously. This means you get it through a tube into a vein in your arm. This lets the medicine go straight into your bloodstream and get to work very quickly.

When do I have to take it?

If you are having your co-trimoxazole in hospital, your doctor or nurse will decide when to give it to you.

If you are taking tablets or the liquid, you will probably take it two times a day, once in the morning and again in the evening. Your doctor will tell you when to take it.

You should take your co-trimoxazole before a meal or at the start of one.

But what if I don't feel like taking it?

Taking your co-trimoxazole is important as it will help you to fight off your infection. If you are having it in hospital your doctor will make sure you get the right amount.

If you are taking your co-trimoxazole at home, it's important to take all of the medicine that your doctor gives you. Your doctor will tell you to take it for at least 5 days. Don't stop taking it before it's all gone, even if you feel better, because if you do some bacteria may survive and the infection could come back.

What should I do if I forget to take it?

If you are having your co-trimoxazole in hospital, your doctor or nurse will make sure you have your treatment at the right time.

If you are taking co-trimoxazole at home and you forget to take a dose, take it as soon as you remember. Don't take twice as much next time to catch up. Remember the three Ds: Don't Double Dose!

How much should I take?

If you are having your co-trimoxazole in hospital your doctor or nurse will give you the right amount.

If you are taking co-trimoxazole at home, your doctor will tell you much to take. You will probably need to take one tablet, or two spoonfuls, twice a day.

How much you take depends on how serious your infection is, and how old you are.

What are the most likely side effects I might get?

The side effects you are mostly to get while taking co-trimoxazole are:

Feeling your heart beat differently from normal

Feeling sick

Having diarrhoea (runny poo)

Oral thrush

Headache

A rash on your skin

If these side effects make you feel unwell, tell your doctor or pharmacist about them.

What other side effects might I get?

Some other side effects you might get from co-trimoxazole include:

Being sick

Having an allergic reaction (signs of this are a skin rash, a swollen face, lips or tongue, and problems breathing)

Are there any other side effects you haven't mentioned?

There are some other very unusual side effects that you could get from co-trimoxazole. These include:

Having a fever (very high temperature)

Lumps or bumps on your skin

Wheezing or finding it difficult to breathe

Ulcers in your mouth

Blisters in your mouth, nose, your bottom or private parts

Red and painful eyes

Being very sensitive to sunlight and burning easily

Feeling tired or weak

Changes to the results of blood tests

Problems with your heart

Yellowish skin

A sore tummy

Blood in your poo

Painful muscles or joints

A stiff neck or sudden headaches

Feeling dizzy

Tingling or numbness in your hands or feet

Seizures

Feeling sad or empty

Seeing lights or things that aren't there

Cloudy wee

If these side effects make you feel unwell, tell your doctor or pharmacist about them.

Is it safe for me to be taking it?

Don't take your co-trimoxazole if you:

Have ever had any blood problems

Have a problem with your kidneys or liver

are allergic to sulfamethoxazole or trimethoprim

You should tell your doctor if:

You have ever had an allergic reaction that has caused blisters around your eyes, mouth and private parts

You have yellowish skin and eyes caused by liver problems

You don't have enough folic acid

You have phenylketonuria

You are very underweight

Your doctor has told you that you have lots of potassium in your blood

Is it ok for me to be taking it if I'm already taking other medicines?

You should tell your doctor about any other medicines that you are taking, or have taken, recently, including herbal medicines.

It's especially important to mention if you are taking:

Medicines that make you wee more

Medicines to treat diarrhoea (runny poo) or malaria

Medicines to help your body accept a transplanted organ

Medicines to help stop your blood clotting

Anything to help treat problems with how your heart beats

Anything to treat flu, shingles or multiple sclerosis

A medicine called methotrexate used to treat cancer

Do I need to know anything else about it?

If you are having any blood tests done, or tests of your wee, make sure you tell your doctor or nurse that you are taking co-trimoxazole.

What if I have any more questions?

If you have any other questions, you can ask your doctor, or chat to other people about co-trimoxazole in the Medikidz forums and virtual world, Mediland.