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Ondansetron Side Effects

For the Consumer

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

Other dosage forms:

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:

More common
Less common
  • Decrease in the frequency of urination
  • decrease in the urine volume
  • difficulty with passing urine (dribbling)
  • painful urination
  • Arm, back, or jaw pain
  • chest pain or discomfort
  • chest tightness or heaviness
  • convulsions
  • cough
  • decreased urine
  • difficulty with breathing
  • difficulty with swallowing
  • dry mouth
  • fast, pounding, or irregular heartbeat or pulse
  • increased thirst
  • loss of appetite
  • loss of bladder control
  • loss of consciousness
  • mood changes
  • muscle pain or cramps
  • nausea or vomiting
  • noisy breathing
  • numbness or tingling in the hands, feet, or lips
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • skin rash, hives, or itching
  • sweating
  • tightness in the chest
  • total body jerking
  • unusual tiredness or weakness
  • wheezing
Incidence not known
  • Blurred vision
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • fixed position of the eye
  • heart stops
  • hoarseness
  • inability to move the eyes
  • increased blinking or spasms of the eyelid
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • no breathing
  • no pulse or blood pressure
  • noisy breathing
  • pounding heartbeat
  • slow or irregular breathing
  • sticking out of the tongue
  • sweating
  • trouble with speaking
  • unconscious
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unusual facial expressions

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:

More common
  • Anxiety
  • difficulty having a bowel movement (stool)
  • dry mouth
  • general feeling of discomfort or illness
  • hyperventilation
  • irritability
  • restlessness
  • shaking
  • trouble sleeping
  • Difficulty with speaking
  • drooling
  • loss of balance control
  • muscle trembling, jerking, or stiffness
  • shuffling walk
  • stiffness of the limbs
  • twisting movements of the body
  • uncontrolled movements, especially of the face, neck, and back
Incidence not known
  • Feeling of warmth
  • hiccups
  • redness of the face, neck, arms, and occasionally, upper chest
  • redness of the skin
  • welts

For Healthcare Professionals

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


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

Nervous system

Dizziness occurred during rapid IV administration.

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

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]


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

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]


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

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]


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]


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

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]


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]


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


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


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

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


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


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


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


1. "Product Information. Zofran (ondansetron)." Cerenex Pharmaceuticals, Research Triangle Pk, NC.

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

4. "Product Information. Zuplenz (ondansetron)." Strativa Pharmaceuticals, a Division of Par Pharmaceuticals, Inc., Woodcliff Lake, NJ.

Some side effects of ondansetron may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.