Generic Name: Ondansetron Brand Name(s): Generics only. No brands available.

Uses

What is ondansetron used for?

Ondansetron is used alone or with other medications to prevent nausea and vomiting caused by cancer drug treatment (chemotherapy) and radiation therapy.

It is also used to prevent and treat nausea and vomiting after surgery. It works by blocking one of the body’s natural substances (serotonin) that cause vomiting.

Ondansetron belongs to a class of medications called 5-HT3 blockers.

How should I take ondansetron?

This medication is dissolved on top of the tongue. It is not meant to be chewed or swallowed like other tablet forms.

Dry your hands before using this medication. This medication may come in a bottle or a blister pack. If using the blister pack, peel back the foil on the blister pack to remove a tablet. Do not push the tablet through the foil. Immediately after removing the tablet, place it on the tongue. Allow it to dissolve completely, then swallow it with saliva. You do not need to take this product with water. Doing so may increase your chance of getting a headache.

To prevent nausea from chemotherapy, take this medication usually within 30 minutes before treatment begins. To prevent nausea from radiation treatment, take this medication 1 to 2 hours before the start of your treatment. To prevent nausea after surgery, take ondansetron 1 hour before the start of surgery. This medication may be taken with or without food. However, your doctor may tell you not to eat before chemotherapy, radiation, or surgery.

Take any other doses as directed by your doctor. Ondansetron may be taken up to 3 times a day for 1 to 2 days after your chemotherapy or radiation treatment is finished. If you are taking this medication on a prescribed schedule, take it regularly in order to get the most benefit from it. To help you remember, take it at the same times each day.

Dosage is based on your medical condition and response to therapy. The dosage for children may also be based on age and weight. In patients with severe liver problems, the usual maximum dose is 8 milligrams in 24 hours. Take this medication exactly as directed. Do not take more medication or take it more often than prescribed. Ask your doctor or pharmacist if you have questions.

Inform your doctor if your condition does not improve or if it worsens.

How do I store ondansetron?

Ondansetron is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store ondansetron in the bathroom or the freezer. There may be different brands of ondansetron that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush ondansetron down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using ondansetron?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of ondansetron or other medications.
  • You have any other illnesses, disorders, or medical conditions.

You should not use ondansetron if:

  • You are also using apomorphine (Apokyn).
  • You are allergic to ondansetron or similar medicines (dolasetron, granisetron, palonosetron).

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using ondansetron during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking ondansetron. Ondansetron is pregnancy risk category B, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from ondansetron?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

  • Blurred vision or temporary vision loss (lasting from only a few minutes to several hours)
  • Severe dizziness, feeling short of breath, fainting, fast or pounding heartbeats
  • Slow heart rate, trouble breathing
  • Anxiety, agitation, shivering
  • Feeling like you might pass out
  • Urinating less than usual or not at all

Less serious side effects may include:

  • Diarrhea or constipation
  • Weakness or tired feeling
  • Fever
  • Headache
  • Dizziness, drowsiness

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with ondansetron?

Ondansetron may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Products that may interact with this drug are:

  • Medicine to treat depression
  • Medicine to treat a psychiatric disorder
  • A narcotic (opioid) medication
  • Medicine to prevent nausea and vomiting

Does food or alcohol interact with ondansetron?

Ondansetron may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with ondansetron?

Ondansetron may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Health conditions that may interact with this drug are:

  • Allergy to other selective 5-HT3 receptor antagonists
  • Bowel blockage
  • Gastric distension (enlarged abdomen)
  • Congestive heart failure
  • Heart rhythm problems (e.g., prolonged QT interval, slow heartbeat)
  • Hypokalemia (low potassium in the blood)
  • Hypomagnesemia (low magnesium in the blood)
  • Heart rhythm problems (e.g., congenital long QT syndrome)
  • Liver disease
  • Phenylketonuria (PKU)

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using ondansetron.

What is the dose of ondansetron for an adult?

For oral dosage forms (oral disintegrating tablets, solution, or tablets):

For prevention of moderate nausea and vomiting after treatment with cancer medicines:

  • At first, 8 milligrams (mg) taken 30 minutes before starting cancer treatment. The 8-mg dose is taken again 8 hours after the first dose. Then, the dose is 8 mg every 12 hours for 1 to 2 days.

For prevention of more severe nausea and vomiting after treatment with cancer medicines:

  • One 24-milligram (mg) tablet taken 30 minutes before starting cancer treatment.

For prevention of nausea and vomiting after radiation treatment:

  • At first, 8 milligrams (mg) taken 1 to 2 hours before radiation treatment. Then, the dose is 8 mg every 8 hours.

For prevention of nausea and vomiting after surgery:

  • 16 milligrams (mg) one hour before anesthesia is given.

For oral dosage form (soluble film):

For prevention of moderate nausea and vomiting after treatment with cancer medicines:

  • At first, one 8-milligram (mg) film taken 30 minutes before starting cancer treatment. The second 8-mg film is taken 8 hours after the first dose. Then, one 8-mg film is taken two times a day (every 12 hours) for 1 to 2 days.

For prevention of more severe nausea and vomiting after treatment with cancer medicines:

  • 24 milligrams (mg) or three 8-mg films taken 30 minutes before starting cancer treatment. Each film should be dissolved in the tongue before taking the next film.

For prevention of nausea and vomiting after radiation treatment:

  • One 8-milligram (mg) film three times a day.

For prevention of nausea and vomiting after surgery:

  • 16 milligrams (mg) or two 8-mg films taken 1 hour before anesthesia is given. Each film should be dissolved in the tongue before taking the next film.

What is the dose of ondansetron for a child?

For oral dosage forms (oral disintegrating tablets, solution, or tablets):

For prevention of moderate nausea and vomiting after treatment with cancer medicines:

  • Teenagers and children 12 years of age—At first, 8 milligrams (mg) taken 30 minutes before starting cancer treatment. The 8-mg dose is taken again 8 hours after the first dose. Then, the dose is 8 mg every 12 hours for 1 to 2 days.
  • Children 4 to 11 years of age—At first, 4 mg taken 30 minutes before starting cancer treatment. The 4-mg dose is taken again 4 and 8 hours after the first dose. Then, the dose is 4 mg every 8 hours for 1 to 2 days.
  • Children younger than 4 years of age—Use and dose must be determined by your doctor.

For prevention of more severe nausea and vomiting after treatment with cancer medicines:

  • Teenagers and children 12 years of age—One 24-milligram (mg) tablet taken 30 minutes before starting cancer treatment.
  • Children younger than 12 years of age—Use and dose must be determined by your doctor.

For prevention of nausea and vomiting after radiation treatment:

  • Use and dose must be determined by your doctor.

For prevention of nausea and vomiting after surgery:

  • Use and dose must be determined by your doctor.

For oral dosage form (soluble film):

For prevention of moderate nausea and vomiting after treatment with cancer medicines:

  • Teenagers, and children 12 years of age—At first, one 8-milligram (mg) film taken 30 minutes before starting cancer treatment. The second 8-mg film is taken 8 hours after the first dose. Then, one 8-mg film is taken two times a day (every 12 hours) for 1 to 2 days.
  • Children 4 to 11 years of age—At first, one 4-milligram (mg) film taken 30 minutes before starting cancer treatment. The second and third 4-mg films are taken 4 and 8 hours after the first dose. Then, one 4-mg film is taken three times a day (every 8 hours) for 1 to 2 days.

How is ondansetron available?

Ondansetron is available in the following dosage forms and strengths:

  • Tablet 4 mg; 8 mg
  • Solution: Injection

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of ondansetron, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: July 25, 2017 | Last Modified: July 25, 2017

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