Ondansetron

Ondansetron is an anti-sickness medicine (sometimes called an antiemetic) that is mainly used to help with nausea and vomiting associated with cancer treatments. The active ingredient ondansetron is a type of medicine called a 5HT3 (serotonin) antagonist. More information

A doctor will review your order and write you a prescription, if appropriate. This prescription is then forwarded to a pharmacy. The pharmacy will have your medicine delivered to you within one to three working days. Read more about this process here.

Service
Instruction costs (includes consult & service fee)
Service – Instruction costs (includes consult & service fee)
Patient Leaflet(s)

What is Ondansetron?

Ondansetron is an anti-sickness medicine (sometimes called an antiemetic) that is mainly used to help with nausea and vomiting associated with cancer treatments. The active ingredient ondansetron is a type of medicine called a 5HT3 (serotonin) antagonist. This medicine works by blocking the 5HT3 receptors that are found in the brain and gut. This stops nausea messages being sent from these areas to the vomiting centre in the brain, thereby preventing or reducing nausea. Ondansetron comes in tablet form. Ondansetron is available at your local pharmacy or we can order it on your behalf from a registered pharmacy in the EU. For prescription medicines we can also arrange a consultation with a registered EU doctor.

What is this medicine used for?

Some medical treatments, such as chemotherapy or radiation therapy, can cause severe nausea and vomiting. Also, nausea occurring after chemotherapy or radiation, referred to as ‘delayed nausea’, is a widespread problem for cancer patients. Ondansetron is typically used to prevent these symptoms. Ondansetron takes one to two hours to become effective and provides six to eight hours of relief.

How to use Ondansetron

Ondansetron is available in tablet form. The tablets should be taken with water, preferably one to two hours before chemotherapy or radiotherapy. This will allow the medicine to be absorbed. Continue to take Ondansetron for several days after the last dose of chemotherapy or radiotherapy to prevent delayed sickness.

Dosage

Unless otherwise prescribed by a doctor, the usual dose is:

  • Adults: one 8-mg dose, one to two hours before the chemotherapy or radiotherapy is started, followed by a second 8-mg dose after 12 hours. For the remaining days: one 8-mg dose twice daily up to a maximum of five days.

Children require a different dose. See the package leaflet for more information on the use of this medicine.

Side effects

Treatment with Ondansetron may cause side effects. The following are some of the side effects that are known to be associated with this medicine:

  • Headache.
  • Constipation or diarrhoea.
  • Hot flashes.
  • Hepatic impairment.

For a complete list of side effects, see the package leaflet. Consult a doctor if the side effects are severe or if you experience side effects that are not listed on the package leaflet.

When not to use this medicine

Ondansetron is not suitable for everyone and should not be used if:

  • You are allergic to ondansetron or any other ingredient in this medicine.
  • You are currently taking apomorphine (a medicine used to treat Parkinson’s disease).

People with intestinal obstruction or constipation, heart disease, or abnormal levels of electrolytes in their blood should use this medicine with caution. This also applies to people who have had recent surgery on their adenoids or tonsils. Ondansetron may interact with certain medicines. Be sure to inform the doctor of any medicines you are currently taking to make sure that the combination is safe. See the package leaflet for more information about contraindications and interactions.

Pregnancy/driving ability/alcohol

If you are pregnant you should not use Ondansetron without consulting a doctor first. Ondansetron should not be used while breastfeeding. This medicine does not affect your ability to drive or interact with alcohol.