Ondansetron

What is ondansetron?

Ondansetron is a medicine that is used to treat or prevent nausea (feeling sick, upset stomach) and vomiting (throwing up). Nausea and vomiting may be due to cancer medicines (chemotherapy), radiation treatments, medicines used for operations (surgery) or other reasons.

Ondansetron may also be used for acute gastroenteritis (stomach virus) or cyclic vomiting syndrome.

You may also hear ondansetron called by its brand names, Zofran or Ondissolve ODF. Ondansetron comes as a liquid, a tablet, an orally disintegrating tablet (ODT), an oral disintegrating film (ODF) and an injection.

Before giving ondansetron to your child:

Tell your child's health-care provider if your child:

• is allergic to ondansetron or any ingredient in the formulation, or other medications in the same drug class such as granisetron or palonosetron

Talk with your child's health-care provider if your child has any of the following conditions. Precautions may need to be taken with this medicine if your child has:

• heart problems, including irregular heart rhythms or heartbeats
• liver disease
• a history of serotonin syndrome

How should you give your child ondansetron?

Follow these instructions when giving your child ondansetron:

• Give ondansetron by mouth exactly as your child's health-care provider tells you.
• Talk to your child's health-care provider before you stop giving ondansetron for any reason.
• If your child needs ondansetron on an as-needed basis only, speak to your child's health-care provider about when you should give it to your child.
• You may be asked to give a dose of ondansetron to your child before going to clinic. If so, give your child ondansetron 30 to 60 minutes before they are given chemotherapy.
• Your child may take ondansetron with or without food. Give ondansetron with food if it upsets your child's stomach.
• If your child is taking the regular tablet, the tablet should be swallowed whole with water. If your child is not able to swallow tablets, the tablets may also be crushed and mixed with liquid or a small amount of food immediately before giving to your child.
• If your child takes the oral disintegrating tablet (ODT) or the oral disintegrating film (ODF):
1. Tear the package along the dotted holes (perforations) to make one dose.
2. Keep the tablet/film in the package until your child is ready to take ondansetron.
3. When your child is ready to take ondansetron, peel back the foil on one of the doses.
4. Remove the tablet/film with dry fingers.
5. Place the tablet or film on top of your child's tongue. It will melt in a few seconds, and then your child should swallow.
• If your child is taking part of an ondansetron tablet, a pill splitter will help. You can buy a pill splitter at your pharmacy.
• If your child is taking the liquid, measure the dose of liquid with the special spoon or syringe that the pharmacist gave you. You may mix the liquid with a small amount of water or milk.
• If your child is prescribed ondansetron injection, a nurse will give it by needle into your child’s vein in the hospital clinic or nursing unit.

What should you do if your child misses a dose of ondansetron?

• Give it as soon as you remember, if your child is feeling sick.
• If it is almost time for the next dose and your child is feeling well, skip the missed dose. Give the next dose at the regular time.
• If you gave the dose late, wait at least four hours after ondansetron before you give the next dose. For example, suppose your child's dose times are 8 a.m., 4 p.m. and midnight. If you miss the 8 a.m. dose and remember to give it at 2 p.m. because your child is feeling sick, then wait until 6 p.m. (four hours later) to give the next dose. Then, go back to the regular dose time.
• Give your child only one dose at a time. However, if your child vomits (throws up) less than 30 minutes after you gave a dose, you may give another dose.

What are the possible side effects of ondansetron?

Your child may have some side effects while they take ondansetron. Check with your child's health-care provider if your child continues to have any of these side effects, if they do not go away, or if they bother your child: 

• Headache
  
• Dizziness
• Constipation
• Diarrhea (loose, watery stools)
• Feeling of warmth or flushing in the face

Call your child's health-care provider as soon as possible, during office hours, if your child has any of these signs:

• Rash, hives (raised, red, itchy areas on the skin) or itching

Most of the following side effects are not common, but they may be a sign of a serious problem. Call your child's health-care provider right away or take your child to the Emergency Department if your child has any of these side effects:

• Allergic reaction (difficulty breathing, swelling of the mouth or throat, increased heart rate, rash, hives)
• Agitation, confusion, hallucinations, poor balance, muscle twitching, shivering, sweating, seizures
• Yellow eyes or skin
• Chest pain, heart pounding or racing (rapid or irregular heart rate), feeling faint

What safety measures should you take when your child is using ondansetron?

There are some medicines that should not be taken together with ondansetron, or, in some cases, the dose of ondansetron or the other medicine may need to be adjusted. It is important that you tell your child's health-care providers if your child takes any other medications (prescription, over the counter or herbal), including:

• antiepileptic medicines, including carbamazepine and phenytoin
• heart medicines, including amiodarone and sotalol
• medicines used to treat mood disorders, including citalopram and sertraline
• certain antibiotics, such as clarithromycin
• antifungals, such as fluconazole or voriconazole
• cisapride
• domperidone
• tramadol
• certain over-the-counter supplements (e.g., St. John's Wort)

This is not a complete list of medications that may interact with ondansetron. Check with your child's health-care provider to start, stop or change the dose of any of your child's drugs (prescription, over-the-counter, vitamin, supplements or natural products).

What other important information should you know about ondansetron?

• If you do not think that ondansetron is working for your child, talk to your child's health-care provider.
• Oral disintegrating tablets (ODT) contain aspartame. Children with phenylketonuria (often called PKU) should not receive aspartame.
• Some ODTs contain gelatin. Some diets do not allow gelatin.
• Keep a list of all medications your child is on and show the list to the health-care provider.
• Do not share your child's medicine with others and do not give anyone else's medicine to your child.
• Make sure you always have enough ondansetron to last through weekends, holidays and vacations. Call your pharmacy at least two days before your child runs out of medicine to order refills.
• Keep ondansetron (regular tablets, ODT, ODF and liquid) at room temperature in a cool, dry place away from sunlight. Do NOT store it in the bathroom or kitchen.
• Do not keep any medicines that are out of date. Check with your pharmacist about the best way to throw away outdated or leftover medicines.
  

Keep ondansetron out of your child’s sight and reach and locked up in a safe place. If your child takes too much ondansetron, call your local Poison Information Centre at one of these numbers. These calls are free. 

• Call 1-844 POISON-X, or 1-844-764-7669, from anywhere in Canada except Quebec.
• Call 1-800-463-5060 if you live in Quebec.