Ondansetron Side Effects

Medically reviewed by Drugs.com. Last updated on Jan 30, 2025.

Applies to ondansetron: film, solution, tablet, tablet disintegrating.

Other dosage forms:

• injection solution

Precautions

Check with your doctor if severe nausea and vomiting continue after leaving the hospital or cancer treatment center.

Do not use this medicine if you are receiving apomorphine (Apokyn®). Using these medicines together may increase risk for more serious problems.

This medicine may cause serious allergic reactions, including anaphylaxis, which can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem including QT prolongation.

Check with your doctor right away if you have anxiety, restlessness, a fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, or see or hear things that are not there. These may be symptoms of a serious condition called serotonin syndrome. Your risk may be higher if you also take certain other medicines that affect serotonin levels in your body.

This medicine may cause a serious heart problem called myocardial ischemia (low blood supply to the heart). Check with your doctor right away if you have chest pain or discomfort, nausea, pain or discomfort in the arms, jaw, back, or neck, sweating, trouble breathing, irregular heartbeat, or vomiting.

Check with your doctor right away if you start to have pain or swelling in your stomach area. These may be signs of a serious stomach or bowel problem.

This medicine may make you dizzy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of ondansetron

Along with its needed effects, ondansetron may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking ondansetron:

Other side effects of ondansetron

Some side effects of ondansetron may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to ondansetron: injectable solution, intravenous solution, oral disintegrating strip, oral solution, oral tablet, oral tablet disintegrating.

General adverse events

The most frequently reported side effects are headache, constipation, and diarrhea.^[Ref]

Nervous system

• Very common (10% or more): Headache (up to 27%), drowsiness/sedation (up to 23%)
• Common (1% to 10%): Dizziness, paresthesia
• Uncommon (0.1% to 1%): Seizures, movement disorders/extrapyramidal reactions (oculogyric crisis/dystonic reactions, dyskinesia)
• Rare (0.01% to 0.1%): Grand mal seizures^[Ref]

Dizziness occurred during rapid IV administration.

Headache occurred more often in the oral dissolving tablet formulation when taken with water.^[Ref]

Other

• Very common (10% or more): Wound problem (up to 28%), malaise/fatigue (up to 13%)
• Common (1% to 10%): Shivers, pyrexia/fever, cold sensation
• Frequency not reported: Pain, ear disorder^[Ref]

Wound problems occurred at the surgical site in patients given this drug for the treatment of postoperative nausea and vomiting.^[Ref]

Gastrointestinal

• Very common (10% or more): Diarrhea (up to 16%), constipation (up to 11%)
• Common (1% to 10%): Xerostomia, nausea, vomiting, localized anal/rectal burning sensation
• Uncommon (0.1% to 1%): Throat disorder
• Frequency not reported: Gastric symptoms, abdominal pain, flatulence^[Ref]

Localized anal/rectal burning occurred after insertion of the suppository formulation.^[Ref]

Ocular

• Very common (10% or more): Eye disorder (up to 19%)
• Common (1% to 10%): Visual disturbance/transient visual disturbances (e.g., blurred vision)
• Uncommon (0.1% to 1%): Oculogyric crisis
• Very rare (less than 0.01%): Transient blindness
• Frequency not reported: Swollen periocular area^[Ref]

Oculogyric crisis occurred alone and in combination with other dystonic reactions.

Transient visual disturbances, blurred vision, and transient blindness occurred predominantly during rapid IV administration. Many of the cases of blindness resolved from within a few minutes to approximately 28 hours. Most patients were receiving concomitant chemotherapy with cisplatin.^[Ref]

Cardiovascular

• Common (1% to 10%): Sensation of warmth/flushing, bradycardia, hypotension, arrhythmias
• Uncommon (0.1% to 1%): Chest pain with/without ST segment depression
• Rare (0.01% to 0.1%): Transient ECG changes including QT interval prolongation (Torsade de Pointes), angina/chest pain, vascular occlusive events, tachycardia
• Frequency not reported: Hemorrhage
• Postmarketing reports: Cardiopulmonary arrest, shock^[Ref]

Cardiopulmonary arrest and shock occurred during allergic reactions in patients given the IV formulation.^[Ref]

Respiratory

• Common (1% to 10%): Hypoxia, lower respiratory tract disease, expectoration, cough
• Uncommon (0.1% to 1%): Hiccups
• Rare (0.01% to 0.1%): Bronchospasm/asthma
• Postmarketing reports: Shortness of breath, laryngeal edema, stridor, laryngospasm^[Ref]

Laryngospasm occurred during allergic reactions in patients given the IV formulation.^[Ref]

Psychiatric

• Common (1% to 10%): Anxiety/agitation, disturbance in behavior/conduct, sleep disturbance^[Ref]

Genitourinary

• Common (1% to 10%): Gynecological disorder, urinary retention, urinary tract infection/dysuria^[Ref]

Dermatologic

• Common (1% to 10%): Rash, pruritus
• Very rare (less than 0.01%): Toxic skin eruption, toxic epidermal necrolysis^[Ref]

Hepatic

• Common (1% to 10%): Asymptomatic increases in AST/ALT
• Postmarketing reports: Liver failure and death^[Ref]

Transient, asymptomatic increases in AST/ALT 2 times the upper limit of normal commonly occurred in patients receiving chemotherapy with cisplatin, and did not appear to be related to dose/duration of treatment.

Liver failure and death have been reported in patients with cancer receiving potentially hepatotoxic/cytotoxic chemotherapy and antibiotics; however, the etiology of liver failure is unknown.^[Ref]

Local

• Common (1% to 10%): Injection site reactions^[Ref]

Hypersensitivity

• Rare (0.01% to 0.1%): Immediate hypersensitivity reactions (sometimes severe), anaphylaxis/anaphylactoid reactions
• Postmarketing reports: Angioedema^[Ref]

Metabolic

• Rare (0.01% to 0.1%): Hypokalemia
• Frequency not reported: Poor oral intake^[Ref]

See also:

Frequently asked questions

• Can you take ondansetron while pregnant?

Further information

Ondansetron side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer