Ondansetron is a commonly prescribed anti-nausea medication available as tablets and oral solutions. It's also sold under the brand name Zofran ODT and is available in generic forms.
It is widely used to prevent nausea and vomiting caused by chemotherapy, radiation therapy, and surgery.
What Are the Uses of Ondansetron Tablets?
Ondansetron tablets are used for preventing nausea and vomiting caused due to some medical treatment. If your symptoms are related to digestive issues, consult our medical gastroenterologists for expert evaluation and personalized treatment.
Off-label use in viral gastroenteritis (doctor-supervised)
How Does Ondansetron Tablet Work?
Ondansetron works by blocking serotonin, a natural chemical in the body that can trigger vomiting and nausea.
This medication is part of a class called serotonin 5-HT3 receptor antagonists. It acts on the nervous system by blocking signals that cause you to feel sick.
Dosage of Ondansetron
Ondansetron is available in various dosage forms to suit different age groups and medical needs, from tablets and oral solutions to fast-acting injections.
Dosage Form
Strengths Available
Common Use
Oral Tablet
4 mg, 8 mg
Nausea and vomiting due to chemotherapy, radiation, or surgery
Orally Disintegrating Tablet (ODT)
4 mg, 8 mg
Easy to take without water, for quick relief
Oral Solution
4 mg/5 mL
Suitable for children or those who can't swallow tablets
Injection (IV/IM)
2 mg/mL (in 2 mL and 4 mL vials)
Used in hospitals for rapid control of nausea and vomiting
Your doctor will determine the right dosage based on your condition, treatment type, and response to the medicine.
Ondansetron Dosage for Child
The dosage of ondansetron for children depends on age and weight, usually 0.15 mg/kg per dose.
Ondansetron Dosage for Adults
Adults are usually prescribed 4-8 mg of ondansetron, taken 1 to 3 times daily to prevent or treat nausea and vomiting.
Typical Dosage Guidelines
Chemotherapy-Induced Nausea
24 mg once, 30 minutes before chemotherapy
8 mg dose before mild chemo
Radiation-Induced Nausea
8 mg taken 1-2 hours before treatment, followed by 8 mg every 8 hours
Surgery-Related Nausea
16 mg dose, 1 hour before receiving anesthesia
Always follow your doctor's exact instructions and do not self-medicate.
How to Take Ondansetron?
The first dosage of Ondansetron is usually taken 30 minutes before starting chemotherapy, 1 to 2 hours before beginning radiation therapy and 1 hour before the surgery.
Some of the additional doses should be taken one or three times a day during the chemo and radiation therapy. It should be continued for 1 to 2 days after the end of the treatment.
Follow the prescription label carefully, and also try to follow the doctor's advice before taking any medicine.
What Should I Do If I Miss a Dose of Ondansetron?
Missing one or two doses won't show any effect on your body.
If you miss a dose some sudden chemical change may affect your body. In some cases, your doctor would advise you to take the prescribed medicine as soon as possible if you have missed the dose.
If it's almost time for your next dose, skip the missed one. Do not double the dose to make up for it. Skipping frequently may reduce effectiveness. In case of overdose or severe side effects, visit your nearest Medicover Hospital for immediate medical care.
What Happens If I Overdose on Ondansetron?
Overdose of a drug can be accidental. If you have taken more than the prescribed Ondansetron tablets there is a chance of getting a harmful effect on your body's functions. Overdose of a medicine can lead to some medical emergency.
Symptoms of Overdose:
Sudden dizziness or fainting
Irregular heartbeat
Blurred vision
Seizures
What to Avoid While Taking Ondansetron
Some habits or substances may reduce the medicine's effect or increase the risk of side effects.
Avoid the Following:
Taking alcohol with the medication
Skipping meals (if advised by your doctor)
Self-medicating with other nausea medicines unless prescribed
Get a second opinion from trusted experts and makeconfident, informed decisions.
If you have any of these serious symptoms, immediately contact your doctor for further assistance. In any case, if you experience any reaction in your body due to Ondansetron, try to avoid it.
What Are the Precautions for Ondansetron?
The product may contain some inactive ingredients that can cause some serious allergic reactions or other serious problems.
Before using the Ondansetron talk with your doctor if you have any medical history, such as:
It can cause a condition that affects the heart rhythm, i.e., QT prolongation. QT prolongation rarely causes serious and irregular heartbeats.
The risk of QT prolongation can be increased if you have a serious medical condition or if you are taking certain medications that can cause QT prolongations.
Warnings for some serious health conditions
For People with Risk Factors for Cardiac Arrhythmias
If you have conditions such as heart failure or congenital long QT syndrome, this drug may increase your risk of arrhythmias.
For People with Phenylketonuria
Ondansetron orally disintegrating tablet contains phenylalanine. Do not take the orally disintegrating tablet if you have phenylketonuria
Pregnant Women
There is no study on humans whether Ondansetron will interact or not. Before taking Ondansetron talk to your doctor.
Breastfeeding
Ondansetron can pass into the breastmilk. So before taking Ondansetron consult with your doctor.
Drug Interactions of Ondansetron
Taking Ondansetron with certain medications or supplements may increase side effects or reduce its effectiveness.
Possible Interactions:
Other drugs that affect heart rhythm (e.g., amiodarone, quinidine)
Medicines that increase serotonin (e.g., SSRIs, SNRIs)
Herbal products like St. John's Wort
Always share your full medication list with your doctor.
How to Store Ondansetron Medicine?
Direct contact with heat, air, and light may damage your medicines.
Expotore of medicine may cause some harmful effects.
The medicine must be kept in a safe place and out of children's reach.
Mainly, the drug should be kept at room temperature between 68ºF and 77ºF (20ºC and 25ºC).
Before taking Ondansetron, consult your Doctor. If you face any problems or get any side effects after taking Ondansetron, rush immediately to your nearby hospital or consult your doctor for better treatment.
Ondansetron vs Metoclopramide
Ondansetron
Metoclopramide
Ondansetron is a prescription drug which comes in the form of tablet and solution. The medication is also available in an intravenous form which is given by the healthcare provider.
Metoclopramide is a prescription drug used for treating gastroesophageal reflux disease, which causes symptoms.
Ondansetron tablets are used for preventing nausea and vomiting caused due to some medical treatment. The treatment includes:
Chemotherapy
Radiation treatment
Surgery
Metoclopramide is used for treating conditions of stomach and intestines. The medication is also used as a short-term treatment for the ongoing heartburn.
Some of the common side effects of Ondansetron are:
Headache
Constipation
Weakness
Tiredness
Chills
Drowsiness
Some of the common side effects of Metoclopramide are
Ondansetron is used for the treatment of pain and nausea. Specifically, Ondansetron is used for the treatment of nausea and vomiting
No, ondansetron is not a narcotic. It’s an anti-nausea medicine that works by blocking serotonin, a chemical that causes vomiting.
Ondansetron may be used during pregnancy if prescribed. Doctors weigh the benefits and risks, especially in early pregnancy.
Ondansetron blocks serotonin, while promethazine works as an antihistamine. Ondansetron causes fewer drowsy side effects.
Yes, ondansetron and Tylenol (acetaminophen) can usually be taken together. Always confirm with your doctor if you’re unsure.
Ondansetron doesn't treat migraines directly but may help reduce nausea often linked to migraine attacks.
Disclaimer: The information provided is accurate and up-to-date to the best of our knowledge. However, it should not be considered a substitute for medical advice or consultation. We do not guarantee its completeness or accuracy. The absence of specific warnings does not mean a medicine is safe for all users. We are not responsible for any outcomes based on this information and strongly recommend consulting a doctor for any medical concerns or questions.
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