Medically reviewed by Jessica Swirble, PharmD
Last updated on 5/24/2024

Drug Information | Side Effects | Use & Dosage | Request a Prescription

The use of ondansetron can lead to various side effects in some individuals.

Common mild side effects of ondansetron use include:

• Headaches
  
• Constipation
  
• Diarrhea
  
• Drowsiness
  
• Fatigue
  
• Anxiety or agitation
  
  

More severe side effects of ondansetron use can include:

• Fast, slow, or irregular heartbeats
  
• Blurred vision or vision loss
  
• Chest pain
  
• Dizziness or lightheadedness
  
• Allergic reactions like skin rash, difficulty breathing, itching, or swelling
  
• Jaundice symptoms like the yellowing of skin or eyes
  
• Agitation, hallucinations, fever, loss of coordination from excessive levels of serotonin in the body
  
• Seizures
  
• Loss of consciousness
  
  

If you experience any severe or concerning side effects while taking ondansetron, contact your healthcare provider right away.

Inform your healthcare provider about any existing medical conditions, allergies, or other medications you are taking before starting treatment with ondansetron. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with ondansetron.

Tell your provider if you are taking these medications or supplements:

• Anticonvulsant medication
  
• Anticoagulant medications
  
• Antiplatelet medications
  
• Antibiotics
  
• Analgesics (pain relievers)
  
• Heart rhythm medications
  
• Opioids
  
• Other medications for nausea
  
• Lithium
  
• Antidepressants (including SSRIs, SNRIs, and MAOIs)
  
• Mood stabilizing medications
  
• Migraine medication
  
  

You should also mention medical conditions such as:

• A history of electrolyte imbalances
  
• A history of heart conditions like heart failure or irregular heartbeats
  
• A family history of long QT syndrome
  
• Liver disease
  
• Intestinal disorders
  
  

If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential risks and benefits of using ondansetron with your healthcare provider.

Take ondansetron exactly as prescribed by your healthcare provider. Do not exceed the recommended dose or length of treatment.

Ondansetron can be taken with or without food. It's important to complete the full course of treatment, especially if it's part of a scheduled regimen around chemotherapy or surgery, to ensure the medication's effectiveness in managing nausea and vomiting.

In case of an ondansetron overdose, seek medical attention immediately. Symptoms of overdose may include severe constipation, vision changes, fainting, or severe dizziness. If you suspect an overdose, contact the poison control helpline at 1-800-222-1222 or call emergency services.