Zofran ODT (Ondansetron) - Oral

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What Is Zofran ODT?

Zofran ODT (ondansetron) is an antiemetic drug that helps prevent nausea and vomiting. This prescription medication dissolves on the top of your tongue and works by preventing a chemical called serotonin from reaching certain cells in the brain. 

Zofran ODT is available as an orally disintegrating tablet. Ondansetron hydrochloride is available in non-disintegrating tablets and an oral solution.

Drug Facts

  • Generic Name: Odansetron
  • Brand Name: Zofran ODT, Zofran, Zuplenz
  • Drug Availability: Prescription
  • Therapeutic Classification: Antiemetic
  • Available Generically: Yes
  • Controlled Substance: N/A
  • Administration Route: Oral
  • Active Ingredient: Odansetron
  • Dosage Form(s): Orally disintegrating tablet, tablet, solution, film

What Is Zofran ODT Used For?

The Food and Drug Administration (FDA) has approved Zofran ODT to prevent:

How to Take Zofran ODT

Zofran ODT comes in a bottle or a foil blister pack. It's important to only open the bottle or remove the tablet from the blister pack right before using it. Also, be sure that your hands are dry.

If you have a foil blister pack, do not push the tablet out of the foil. Instead, peel the foil backing off the blister and gently remove the tablet. Do not break or crush any tablets.

As soon as you remove the tablet from the bottle or foil blister pack, immediately place it on the top of your tongue and let it dissolve on its own. This will take seconds, at which point you can then swallow the rest of the tablet with your own saliva. You do not need to drink water and should not swallow the pill whole or try and chew it.

The timing of when to take your Zofran ODT depends on what it is being used for.

If you are undergoing chemotherapy, Zofran ODT is typically taken 30 minutes prior to the start of treatment.

On the other hand, if you are undergoing radiation, Zofran ODT is taken one to two hours beforehand. Your Zofran ODT dosing may then continue for one to two days after treatment is finished. To prevent nausea and vomiting after surgery, people usually take Zofran ODT one hour before the start of general anesthesia.

As with any drug, it’s essential to take Zofran ODT exactly as prescribed by your healthcare provider. If at any time you have questions about your Zofran ODT, or you feel like it isn't helping you, don't hesitate to reach out to your healthcare team.


Store the Zofran ODT bottle or foil blister pack at room temperature or in the refrigerator. Be sure to keep your medication out of reach of children and pets.

Off-Label Uses

Healthcare providers prescribe Zofran ODT off-label to treat certain health conditions not specified on the product label, such as:

Using a drug off-label means that a healthcare provider relies on their medical knowledge and insight to prescribe it for a patient even though it’s not technically FDA-approved for that condition.

How Long Does Zofran ODT Take to Work?

Zofran begins to work within 30 minutes of taking it and reaches peak blood levels within one to two hours.

What Are the Side Effects of Zofran ODT?

This is not a complete list of side effects, and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 1-800-FDA-1088.

Zofran ODT can cause mild or severe side effects.

Common Side Effects

The side effects of Zofran ODT may vary slightly depending on the reason the drug is being taken.

Common side effects of taking Zofran ODT for the prevention of nausea/vomiting caused by chemotherapy are:

  • Headache
  • Tiredness
  • Constipation
  • Diarrhea

Common side effects of taking Zofran ODT for the prevention of nausea and vomiting caused by radiation are:

  • Headache
  • Constipation
  • Diarrhea

Common side effects of taking Zofran ODT for the prevention of nausea and vomiting after surgery are headache and low oxygen levels in your bloodstream—what’s known as hypoxia.

Severe Side Effects

Contact your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening, or if you think you’re having a medical emergency.

Serious side effects are uncommon, but they may occur when taking Zofran ODT.

One serious side effect associated with Zofran ODT use is serotonin syndrome—a condition caused by elevated serotonin levels in your body.

Possible symptoms and signs of serotonin syndrome include:

  • Agitation 
  • Hallucinations
  • Rapid heart rate
  • Severe dizziness
  • Unusual sweating or flushing
  • Twitching or rigid muscles
  • Loss of balance
  • Seizure
  • Severe nausea/vomiting/diarrhea

Zofran ODT has also been associated with an electrical disturbance of the heart called QT prolongation. Seek medical attention immediately if you experience chest pain, an abnormal heartbeat (too slow, fast, or irregular), severe lightheadedness, or fainting. 

Also, seek emergency medical help if you have symptoms or signs of a serious allergic reaction called anaphylaxis to Zofran ODT:

  • Rash such as hives
  • Wheezing or trouble breathing 
  • Swelling of your face, lips, tongue, or throat 
  • Severe lightheadedness
  • Fever
  • Chills

Lastly, if you have just had abdominal surgery or are taking chemotherapy, Zofran ODT may mask the signs and symptoms of a bowel obstruction. Speak to your healthcare team if you experience stomach cramping or swelling after taking Zofran ODT.

Report Side Effects

Zofran ODT may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting Program or by phone (1-800-332-1088).

Dosage: How Much Zofran ODT Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

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

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

  • Adults, 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:

  • Adults, 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:

  • Adults—At first, 8 milligrams (mg) taken 1 to 2 hours before radiation treatment. Then, the dose is 8 mg every 8 hours.
  • Children—Use and dose must be determined by your doctor.

For prevention of nausea and vomiting after surgery:

  • Adults—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.
  • Children—Use and dose must be determined by your doctor.

For prevention of nausea and vomiting after radiation treatment:

  • Adults—One 8-milligram (mg) film three times a day.
  • Children—Use and dose must be determined by your doctor.

For prevention of nausea and vomiting after surgery:

  • Adults—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.
  • Children—Use and dose must be determined by your doctor.


There are no specific Zofran ODT dosing adjustments for older patients.

For children, Zofran ODT dosing is slightly different than for adults. For example, the manufacturer recommends that young children between the ages of 4 and 11 take a 4-mg Zofran ODT tablet before starting chemotherapy (instead of an 8-mg tablet, which adults take).

Young children are advised to take 4 mg of Zofran ODT three times a day for one to two days after chemotherapy is finished. This is slightly different from adults, who are advised to take 8 mg two times a day for one to two days after completing chemotherapy.

If you are pregnant, it’s important to talk to your healthcare provider before taking Zofran ODT. It hasn’t been confirmed yet whether Zofran ODT can cause harm to an unborn baby.

Until the medical community knows more, Zofran ODT is generally recommended only for severe cases of nausea/vomiting in pregnancy and when other therapies have failed.

Be sure to also tell your provider if you are breastfeeding. It’s not known if Zofran ODT passes into breast milk. You and your provider should carefully review the risks and benefits of taking Zofran ODT while breastfeeding.

Missed Dose

If you miss a dose of Zofran ODT, take it as soon as you remember, unless it is almost time for your next dose. In that case, skip your missed dose and take your Zofran ODT at your regularly scheduled time.

As a reminder, don’t take two doses simultaneously or an extra dose to make up for the missed dose. If you find that you are missing doses often, consider using a pill container or setting an alarm on your phone or watch.

Overdose: What Happens If I Take Too Much Zofran ODT?

Cases of accidental Zofran overdose in children have been reported. Their symptoms were consistent with serotonin syndrome.

While not an exhaustive list, these symptoms include:

  • Sleepiness
  • Agitation
  • Fast heartbeat
  • Unusual flushing
  • Sweating

One Zofran overdose was reported in an adult who experienced low blood pressure and felt faint.

What Happens If I Overdose On Zofran ODT?

If you think you or someone else may have overdosed on Zofran ODT (ondansetron), call a healthcare provider or the Poison Control Center (1-800-222-1222).

If someone collapses or isn't breathing after taking ondansetron, call 911 immediately.


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Check with your doctor if severe nausea and vomiting continue after leaving the hospital or cancer treatment center.

Do not use this medicine if you are receiving apomorphine (Apokyn®). Using these medicines together may increase risk for more serious problems.

This medicine may cause serious allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem such as QT prolongation.

Check with your doctor right away if you start to have pain or swelling in your stomach area. These may be signs of a serious stomach or bowel problem.

This medicine may make you dizzy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Zofran ODT?

You should not take Zofran ODT if you have a known allergy or sensitivity to the medication or any of its ingredients.

Patients with a genetic condition called phenylketonuria (PKU) should be cautious taking Zofran ODT. Zofran ODT contains phenylalanine (a chemical in the artificial sweetener aspartame). 

You should not take Zofran ODT if you take a medication used to treat advanced Parkinson’s disease called Apokyn (apomorphine).

What Other Medications Interact With Zofran ODT?

When taken with Zofran ODT, several medications may increase your risk of developing serotonin syndrome. Along with Zofran ODT, if you are taking a medicine that increases serotonin levels in the body, your doctor may need to choose a different treatment or monitor you more closely.

Drugs that elevate serotonin levels include:

  • Selective serotonin reuptake inhibitors (SSRIs), such as Prozac (fluoxetine) or Zoloft (sertraline) 
  • Selective norepinephrine reuptake inhibitors (SNRIs), such as Cymbalta (duloxetine) or Effexor (venlafaxine)
  • Tricyclic antidepressants, such as Elavil (amitriptyline) and Pamelor (nortriptyline)
  • Triptans, such as Imitrex (sumatriptan)
  • Drugs of abuse, like cocaine, MDMA (“Ecstasy”), and LSD
  • St. John’s wort
  • Delsym (dextromethorphan)

The list above is not complete, so be sure to tell your healthcare provider of all the medications you are taking, including prescription and over-the-counter drugs, herbal products, supplements, vitamins, and recreational drugs.

Lastly, there is some evidence that Zofran ODT may decrease the effectiveness of the pain medication ConZip (tramadol) when taken together. Therefore, if you take Zofran ODT with tramadol, your provider may need to closely monitor your pain control.

What Medications Are Similar?

Besides Zofran ODT, other antiemetic medications may help prevent or treat your nausea and vomiting.

Two drugs that most closely resemble Zofran ODT are Anzemet (dolasetron) and the generic drug granisetron (the brand-name Kytril has been discontinued in the United States). These drugs also work by blocking the effects of serotonin in the body.

That said, only Zofran is available as an orally disintegrating tablet (ODT). Taking an ODT may be particularly appealing for patients who find it difficult to swallow a whole pill due to their upset stomach.

Moreover, only Zofran ODT is FDA-approved to prevent nausea and vomiting caused by chemotherapy, radiation, and surgery. The other antiemetics are approved for only one or two of these circumstances. 

Besides drugs that block the action of serotonin, other antiemetics include:

When choosing which antiemetic is best for you, your medical provider will consider several factors, such as the health problem/circumstance associated with your nausea/vomiting and the drug’s potential for side effects and interactions. The cost and availability of the drug also usually play a role.

Frequently Asked Questions

  • What is Zofran ODT used for?

    Zofran ODT is approved by the FDA to prevent nausea and vomiting in patients undergoing cancer drug treatment (chemotherapy) or radiation. Zofran ODT is also FDA-approved to prevent postoperative nausea and vomiting.

    Zofran ODT is also sometimes used off-label to treat diarrhea associated with carcinoid syndrome, gastroparesis, and nausea/vomiting associated with pregnancy or dizziness.

  • How does Zofran ODT work?

    Zofran ODT belongs to a class of drugs called 5-HT3 receptor antagonists. It works by preventing serotonin from binding and activating certain cells in your body that would normally trigger nausea and vomiting. These vomiting-inducing cells are located in your brain and your vagus nerve.

  • What are the side effects of Zofran ODT?

    The most common side effects associated with Zofran ODT are:

    • Headache
    • Feeling tired or under the weather
    • Constipation
    • Diarrhea

    Serious side effects of Zofran are not common but include serotonin syndrome, QT prolongation, and anaphylaxis.

  • What drugs should not be taken with Zofran ODT?

    You cannot take Zofran ODT if you are taking: 

    • Apokyn (apomorphine), which is a medication used to treat patients with advanced Parkinson's disease
    • One or more drugs that raise serotonin levels in your body

How Can I Stay Healthy While Taking Zofran ODT?

Staying healthy while taking Zofran ODT means sticking to a few essential principles.

When prescribed this medication, whether it's for an FDA-approved indication or off-label use (e.g., pregnancy or gastroparesis), be open and ask your healthcare provider specifically why it is safe and reasonable for you to take. During your discussion, be honest about your medical history and any medications/herbal products/recreational drugs you take.

In addition, take Zofran ODT only for the indication prescribed.

For example, let's say you were asked to take Zofran before and after your chemotherapy sessions. Once your sessions are complete, do not take any leftover Zofran tablets to ease nausea/vomiting associated with a different ailment, like motion sickness or seasickness. Zofran works in a specific way, so it may not be effective for that particular cause of your stomach sickness. Also, the pros of taking it for that indication may not outweigh the potential risks.

You also want to be sure to take Zofran exactly as prescribed by your provider, even if you are "feeling well" at that moment. Remember that Zofran is technically a preventive medication, so taking it before your stomach gets upset is key.

Lastly, be careful not to share your medication with anyone. It's not safe for certain people to take Zofran, and this determination can only be made after a medical history has been obtained by a healthcare professional.

Remain committed to feeling well, continue to use the resources you have available, and don’t be reluctant to reach out to loved ones for support and comfort during this trying time.

Medical Disclaimer

Verywell Health's drug information is meant for education purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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