Explanation

Ondansetron (also called Ondemet and Zofran®) is a medicine that you take with chemotherapy or radiotherapy to stop you feeling sick or being sick.

It's called an anti-emetic drug.

It belongs to a family of medicines called selective 5HT-3 receptor antagonists. This just means that it blocks only the activity of a neurotransmitter called 5HT-3.

What does it do?

Ondansetron works by blocking the chemicals in your stomach and brain that make you feel sick.

What does it look like?

You can get ondansetron as an injection, tablet or melt. A melt is a tablet that dissolves on your tongue.

Ondansetron also comes as a suppository

When do I have to take it?

Your doctor will tell you exactly when you need to take ondansetron and how often. It depends on your age, how much you weigh, and what other types of treatment you're having.

If you are getting ondansetron as an injection, it will be given to you through a tube into one of your veins. This is called an intravenous infusion and takes about 15 minutes.

If you take the tablet, you can just swallow it with a glass of water.

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

If you don't take your ondansetron, then the chemotherapy or radiotherapy you are taking will most likely make you feel sick.

If you don't want to feel sick, then you need to take your ondansetron!

What should I do if I forget to take it?

If you are getting ondansetron in hospital, then your doctor or nurse will make sure you get the right amount at the right time, so you don't have to worry about remembering when to take it.

If you are taking tablets, your doctor will tell you when you need to take it. If you do forget to take your ondansetron and you feel sick, just take it when you remember and carry on taking it as usual.

If you don't feel sick, just take it when you next would usually. Don't take twice as much next time to catch up. Remember the three Ds: Don't Double Dose!

How much do I take?

That depends on how much you weigh and the type of chemotherapy or radiotherapy you are having. Your doctor will decide the perfect dose for you.

The right dose is important. It's the best way to help you feel better, without getting side effects.

What are the most likely side effects I might get if I take ondansetron?

The side effects you are most likely to get with ondansetron are:

Constipation (finding it hard to have a poo, or not having poos very often)

Your skin feeling warm

Headache

Hiccups

What other side effects might I get?

Some less likely side effects that you might get from ondansetron are:

A pain in your chest

Changes in how your heart beats, or feeling it beating heavily

Making twitchy or jerky movement

Having seizures

Getting an itchy rash at the place where it has been injected

Changes in how your liver is working (shown by blood tests)

If you notice any of these side effects tell your doctor immediately.

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

There are some other side effects that you could get, although these are rare. They include:

Anaphylaxis. This need to be treated straight away. Tell your doctor or hospital immediately if your face, arms or legs suddenly start to swell up, or you start finding it hard to breathe

Dizziness if you are having ondansetron at hospital as an injection

Tell your doctor if any of the side effects become really bad or troublesome, or if you notice any other side effects not listed here.

Is it safe for me to be taking ondansetron?

Before you take ondansetron, tell your doctor if you are allergic to it or any of its ingredients.

You should also tell your doctor about any other medical problems that you know you have, especially if you:

Have a blockage in your gut or are really constipated (find it hard to do a poo)

Have had an allergic reaction to other types of medicines that stop you feeling sick or being sick

Have a problem with your heart

Have a problem with your liver

Is it ok for me to be taking ondansetron if I am taking other medicines?

Make sure you tell your doctor about all the other medicines you're taking.

You should also mention things you're taking for other medical problems, including drugs, special foods or herbal remedies.

It's especially important to tell your doctor if you're taking:

tramadol (a painkiller)

any medicines for epilepsy

an antibiotic called rifampicin

Do I need to know anything else about ondansetron?

Ondanstron may affect the results of blood tests that check how well your liver is working.

What if I have any more questions?

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