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Ondansetron: Side Effects, Uses and Interactions

Ondansetron: Side Effects, Uses, Dosage and Interactions

GENERIC NAME: Ondansetron (oral)
BRAND NAME: Zuplenz, Zofran, Zofran ODT
DRUG CLASS: 5HT3 Receptor Antagonists


Ondansetron is a medication used to prevent vomiting and nausea caused by cancer radiation therapy, chemotherapy or surgery. It can also be effective for treating gastroenteritis but ineffective for treating vomiting caused by the motion sickness (travel sickness). It can be taken by mouth or can be injected into a muscle or a vein.


Ondansetron can be taken with or without meal. Take ondansetron exactly as prescribed by your doctor or health care provider. Follow all the instructions written on your prescription label. Do not take Ondansetron medication in smaller or larger amounts or for longer than recommended.

Store at room temperature, away from heat and direct light. Do not freeze. Keep out of the reach of children.


Ondansetron Side Effects

Common Ondansetron side effects may include:

  • Diarrhea
  • Headache
  • Sleepiness
  • Constipation
  • Itchiness

Call your doctor immediately if you have:

  • Stomach pain
  • Bloating
  • QT prolongation
  • Severe allergic reaction
  • Severe constipation
  • Irregular heartbeat
  • Blurred vision
  • Headache with chest pain and severe dizziness
  • Jaundice (yellowing of the skin or eyes)
  • High levels of serotonin in the body (hallucinations, fever, agitation, overactive reflexes, fast heart rate, nausea, vomiting, diarrhea, fainting and loss of coordination)

Some of the rare side-effects of Ondansetron may include:

  • Chest tightness or heaviness
  • Convulsions
  • Cough
  • Decreased urine
  • Arm, back, or jaw pain
  • Difficulty with swallowing
  • Loss of bladder control
  • Chest pain or discomfort
  • Sweating
  • Dry mouth
  • Fast, pounding, or irregular heartbeat or pulse
  • Increased thirst
  • Loss of consciousness
  • Noisy breathing
  • Difficulty with breathing
  • Tightness in the chest
  • Muscle pain or cramps
  • Loss of appetite
  • Wheezing
  • Nausea or vomiting
  • Mood changes
  • Skin rash, hives, or itching
  • Total body jerking
  • Unusual tiredness or weakness
  • Numbness or tingling in the hands, feet, or lips
  • Puffiness or swelling of the eyelids or around the face, eyes, lips, or tongue


Taking  Ondansetron with some other medicines may change its effectiveness or may lead to the risk of serious health side-effects. Do not start or stop taking any medicine immediately or don not change the dosage of any medicine without the approval of your doctor or health care provider. Take all medicines under the supervision or guidance of your doctor.

Some drugs that may interact with Ondansetron include:

  • Apomorphine
  • Dronedarone
  • Cyclophosphamide
  • Cisapride
  • Fluconazole
  • Ketoconazole
  • Mesoridazine
  • Bepridil
  • Piperaquine
  • Ziprasidone
  • Nelfinavir
  • Terfenadine
  • Pimozide
  • Posaconazole
  • Saquinavir
  • Thioridazine
  • Sparfloxacin


You shouldn’t use this medicine if:

  • You’re also using Apomorphine (Apokyn).
  • You’re allergic to ondansetron or similar medicines such as Granisetron, Dolasetron, Palonosetron.

Before taking Ondansetron medication, tell your doctor about the medical history; especially of:

  • Liver disease
  • Bowel blockage
  • Low levels of potassium in the blood (hypokalemia)
  • Low levels of magnesium in the blood (hypomagnesemia)
  • Congestive heart failure, slow heartbeats
  • A personal or family history of long QT syndrome

This medicine is not approved for use by anyone younger than 4 yrs old.

Ondansetron is not expected to harm an unborn baby. However, tell your doctor if you are pregnant or planning to get pregnant.

It is not known whether this medicine passes into the breast milk or if it could harm a nursing baby. Tell your doctor or health care provider if you are breast-feeding.


Take the missed dose of Ondansetron as soon as you remember. Skip the missed dose if it is almost the time for next scheduled dose. Do not take extra medicine to make up the missed dose.


Ondansetron overdose symptoms may include:

  • Fainting
  • Sudden loss of vision
  • Severe constipation
  • Feeling light-headed

In case of overdose, seek emergency medical help or see your doctor immediately.



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