Ondansetron

Description

Ondansetron is an antiemetic medicine used to treat and prevent nausea and vomiting caused by surgery, cancer medicines (chemotherapy) or radiation therapy. It works by blocking a natural substance called serotonin in the brain that causes nausea and vomiting. This medicine starts to work in 1 to 2 hours. Common side effects of Ondansetron are constipation, headache and dizziness. Do not use this medicine if you are previously allergic to it. Inform your doctor if you have any disease conditions like liver disease, heart failure, slow heartbeats, electrolyte imbalance, stomach or intestine blockage disorders before using this medicine. Always make sure that Ondansetron is safe for you to use. Ondansetron is available in many different forms like tablet, injection, syrup, films, oral drops and solution. Your doctor will decide an appropriate dosage form and dose based on your condition. You may have to take this medicine 30 minutes before the start of chemotherapy, 1-2 hours before the start of radiation therapy, or 1 hour before surgery. If you vomit this medicine within one hour of taking it, then you need to repeat the dose.

Side effects

Major & minor side effects for Ondansetron

  • Headache
  • Constipation
  • Fatigue
  • Fast or slow or irregular heartbeat
  • Chills
  • Dry mouth
  • Anxiety
  • Excessive sweating
  • Dizziness
  • Skin rash and hives
  • Injection site pain

Uses of Ondansetron

What is it prescribed for?

  • Chemotherapy induced nausea and vomiting
  • Post operative nausea and vomiting
  • Radiation induced nausea and vomiting
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Concerns

Commonly asked questions

  • Onset of action
    The onset of action for ondansetron can be observed within 30 minutes for injection and 2 hours for the oral forms. It stops you from feeling sick immediately.
  • Duration of effect
    The effect of ondansetron lasts for a duration of 12 to 28 hours.
  • Safe with alcohol?
    Interaction with alcohol is unknown. It is advisable to consult your doctor before consumption.
  • Is it habit forming?
    No habit-forming tendencies were reported for Ondansetron
  • Usage in pregnancy?
    Ondansetron is relatively safe to use in pregnant women. It is sometimes used to treat nausea and vomiting during the first trimester. But it is known to cause birth defects, particularly heart and kidney defects and therefore should only be used upon your doctor's recommendation.
  • Usage while breast-feeding?
    It is not known whether Ondansetron can be used in breastfeeding mothers or not. An alternate medication may be preferred, especially while nursing a newborn or preterm infant. However, your doctor may prescribe this medicine if the benefits outweigh the risks.

Allergy

Avoid taking Ondansetron if you are previously allergic to it. Allergic reactions to this medicine are rare. Seek immediate medical attention if you notice any symptoms of allergic reactions such as skin rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, breathing difficulties, etc.

Apomorphine

Apomorphine is used to treat symptoms of Parkinson's disease. The combined use of Ondansetron and apomorphine is not recommended due to the risk of lightheadedness, loss of consciousness, and low blood pressure.
Warnings for special population

Pregnancy

Ondansetron is relatively safe to use in pregnant women. It is sometimes used to treat nausea and vomiting during the first trimester. But it is known to cause birth defects, particularly heart and kidney defects and therefore should only be used upon your doctor's recommendation.

Breast-feeding

It is not known whether Ondansetron can be used in breastfeeding mothers or not. An alternate medication may be preferred, especially while nursing a newborn or preterm infant. However, your doctor may prescribe this medicine if the benefits outweigh the risks.
General warnings

Electrolyte imbalances

Low levels of potassium or magnesium in the blood should be corrected before starting treatment with Ondansetron.

Intestinal obstruction

Use Ondansetron cautiously in patients with intestinal obstruction diseases such as colon cancer, Crohn's disease or diverticulitis because this medicine can delay the time for food to move through the entire intestine (bowel transit time).

Serotonin syndrome

Serotonin syndrome is a condition where your body produces too much of a chemical called serotonin. This occurs when you take medicines that cause high levels of serotonin in your body. This chemical helps your brain cells and nerve cells to communicate with each other. But too much serotonin causes extreme nerve cell activity and serious symptoms. Caution should be taken when Ondansetron is used along with other same class of medications like granisetron, dolasetron, etc., as it may increase the risk of serotonin syndrome.

Overdose

Oral forms: Seek emergency medical attention or contact the doctor in case of overdose. Injection: Since ondansetron is administered in the hospital or clinical setting by a qualified healthcare professional, the chances of an overdose are very low. However, emergency medical treatment will be initiated by the doctor if an overdose is suspected.
All drugs interact differently for person to person. You should check all the possible interactions with your doctor before starting any medicine.
Interaction with Alcohol

Description

Interaction with alcohol is unknown. It is advisable to consult your doctor before consumption.

Instructions

Interaction with alcohol is unknown. It is advisable to consult your doctor before consumption.
Interaction with Medicine

Amitriptyline

Carbamazepine

Phenytoin

Tramadol

Amiodarone

Apomorphine

Disease interactions

QT Prolongation

Ondansetron may cause a heart rhythm problem called prolonged QT intervals (an electrical heartbeat disturbance) in some patients who are taking heart medications. It may result in fast, rapid, and irregular heartbeats.

Liver Disease

The primary conversion of Ondansetron to its active form happens in the liver. Therefore patients with liver diseases need special consideration while taking Ondansetron.
Food interactions
Information not available.
Lab interactions
Information not available.
Ondansetron uses for treating nausea and vomiting is widely accepted. Oral forms: Take ondansetron as instructed by your doctor. Avoid eating heavy meals before taking ondansetron. Eat small snacks or light foods and also drink water to avoid dehydration while taking this medicine. Injection: The medicine should be administered by a qualified healthcare professional in a clinic or hospital.
Miscelleneous

Can be taken with or without food, as advised by your doctor

To be taken as instructed by doctor

Does not cause sleepiness

How it works
Ondansetron works by blocking a natural substance called serotonin in the brain that causes nausea and vomiting.
Legal Status

Approved

Approved

Approved

Approved

Classification

Category

Antiemetics, 5HT3 receptor antagonists

Schedule

OTC

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https://medlineplus.gov/druginfo/meds/a601209.html>

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https://www.medicines.org.uk/emc/medicine/28489>

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https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/020103s035_020605s019_020781s019lbl.pdf>

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Information on this page was last updated on 22 Feb 2021

Disclaimer

We’ve made all possible efforts to ensure that the information provided here is accurate, up-to-date and complete, however, it should not be treated as a substitute for professional medical advice, diagnosis or treatment. Practo only provides reference source for common information on medicines and does not guarantee its accuracy or exhaustiveness. The absence of a warning for any drug or combination thereof, should not be assumed to indicate that the drug or combination is safe, effective, or appropriate for any given patient. Practo does not assume any responsibility for any aspect of healthcare administered with the aid of information provided above. If you have any doubts about your medication then we strongly recommend that you consult with your doctor, nurse or healthcare provider. See detailed T&C here.