Skip to content
My WebMD Sign In, Sign Up

ondansetron HCl oral

Important Note

Warnings
Uses
Side Effects
Precautions
Interactions
Overdose
ondansetron HCl oral Uses

This medication 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 causes vomiting.

How to use ondansetron HCl oral

To prevent nausea from chemotherapy, take this medication by mouth usually within 30 minutes before treatment begins. To prevent nausea from radiation treatment, take this medication by mouth 1 to 2 hours before the start of your treatment. To prevent nausea after surgery, take ondansetron by mouth 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.

If you are using the liquid form of this medication, use a special measuring spoon or device to measure out your prescribed dose. Do not use a household spoon because you may not get the correct dose.

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. The usual maximum dose in patients with severe liver problems 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.

ondansetron HCl oral Side Effects

Headache, lightheadedness, dizziness, drowsiness, tiredness, or constipation may occur. If these effects persist or worsen, notify your doctor promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: stomach pain, muscle spasm/stiffness, vision changes (e.g., temporary loss of vision, blurred vision).

Get medical help right away if any of these rare but very serious side effects occur: chest pain, slow/fast/irregular heartbeat, severe dizziness, fainting.

A very serious allergic reaction to this drug is unlikely, but stop taking this medication and seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

ondansetron HCl oral Precautions

Before taking ondansetron, tell your doctor or pharmacist if you are allergic to it; or to other serotonin blockers (e.g., granisetron); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: irregular heartbeat, liver disease, stomach/intestinal problems (e.g., recent abdominal surgery, ileus, swelling).

Ondansetron may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using ondansetron, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using ondansetron safely.

This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

To minimize dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.

It is not known whether this drug passes into breast milk. Consult your doctor before breast-feeding.

ondansetron HCl oral Interactions

Your healthcare professionals (e.g., doctor or pharmacist) may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop or change the dosage of any medicine before checking with them first.

This drug should not be used with the following medication because a very serious interaction may occur: apomorphine.

If you are currently using the medication listed above, tell your doctor or pharmacist before starting ondansetron.

Before using this medication, tell your doctor of all nonprescription and prescription medication you may use, especially of: tramadol.

Ask your doctor or pharmacist for more details.

Many drugs besides ondansetron may affect the heart rhythm (QT prolongation), including dofetilide, pimozide, procainamide, amiodarone, quinidine, sotalol, macrolide antibiotics (such as erythromycin), among others. Therefore, before using ondansetron, report all medications you are currently using to your doctor or pharmacist.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

ondansetron HCl oral Overdose

If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

NOTES:

Do not share this product with others.

Laboratory and/or medical tests (such as EKG) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

MISSED DOSE:

Try to take each dose at the scheduled time. If you miss a dose, take it as soon as remembered unless it is near the time for the next dose. In that case, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE:

Tablets may be stored in the refrigerator or at room temperature between 36-86 degrees F (2-30 degrees C). Store the liquid form at room temperature between 59-86 degrees F (15-30 degrees C).

Store away from light and moisture. Do not store in the bathroom. Keep all medicines out of reach of children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

Information last revised March 2013. Copyright(c) 2013 First Databank, Inc.

See 66 Reviews for this Drug. - OR -

Review this Treatment

Find a Drug:

by name or medical condition or shape/color (Pill Identifier)

(for example: aspirin)

(for example: diabetes)

Report Problems to the Food and Drug Administration
 
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Ask the pharmacist

Questions about medications? Get expert answers by video or live chat about allergies, pregnancy, sleep, and more.
See the Ask the Pharmacist event schedule.

Ask a Question

Popular Slideshows & Tools on WebMD

hands on abdomen
Can you catch one?
Woman sitting in front of UV lights
Is yours working?
woman using breath spray
What's causing yours?
womans hand on abdomen
Are you ready for baby?
MS Overview
Recognizing symptoms.
bowl of yogurt with heart shape
Eat for a healthy heart.
woman doing pushups
To help you get fit.
Colored x-ray of tooth decay
Know what to look for.
Woman sitting with child
Do you know the symptoms?
mosquito
Stings, bites, burns, and more.
Allentown, PA
Are you living in one?
Thyroid exam
See how much you know.

Women's Health Newsletter

Find out what women really need.

WebMD the app

Get trusted health information. Whenever. Wherever... with your iPhone, iPad or Android.

Find Out More

IMPORTANT: About This Section and Other User-Generated Content on WebMD

The opinions expressed in WebMD User-generated content areas like communities, reviews, ratings, or blogs are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. User-generated content areas are not reviewed by a WebMD physician or any member of the WebMD editorial staff for accuracy, balance, objectivity, or any other reason except for compliance with our Terms and Conditions. Some of these opinions may contain information about treatment or uses of drug products that have not been approved by the U.S. Food and Drug Administration. WebMD does not endorse any specific product, service, or treatment.

Do not consider WebMD User-generated content as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare provider because of something you have read on WebMD. You should always speak with your doctor before you start, stop, or change any prescribed part of your care plan or treatment. WebMD understands that reading individual, real-life experiences can be a helpful resource but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified health care provider. If you think you may have a medical emergency, call your doctor or dial 911 immediately.