Zofran Side Effects Center

Last updated on RxList: 11/2/2021
Zofran Side Effects Center

What Is Zofran?

Zofran (ondansetron) is an antiemetic and selective 5-HT3 receptor antagonist prescribed for the treatment of nausea and vomiting due to cancer chemotherapy and also used to prevent and treat nausea and vomiting after surgery. Zofran is available in generic form.

What Are Side Effects of Zofran?

Common side effects of Zofran include:

  • diarrhea,
  • headache,
  • fever,
  • lightheadedness,
  • dizziness,
  • weakness,
  • tiredness,
  • drowsiness, 
  • malaise/fatigue,
  • gynecologic disorder,
  • anxiety
  • Urinary retention,
  • severe itching,
  • elevated liver function test results
  • constipation,
  • rash,
  • blurred vision, and
  • muscle spasm.

Other side effects of Ondansetron include:



  • fainting (rarely and predominantly with intravenous ondansetron)
  • transient ECG changes including QT/QTc interval prolongation have been reported


  • nausea
  • vomiting


  • ECG alterations: heartbeat irregularities; prolongation of PR, QRS, and QT intervals


  • specific hepatic enzyme abnormalities
  • hepatic necrosis
  • abnormal hepatic function


  • flushing
  • rare cases of hypersensitivity reactions, sometimes severe (acute allergic reactions, rapid swelling, difficulty breathing, cardiopulmonary arrest, low blood pressurelaryngeal edema, laryngospasm, shock, shortness of breath, or stridor)

Local reactions

  • pain, redness, and burning at the injection site

Lower respiratory

  • involuntary intermittent or sustained deviation of the eyes, appearing alone, as well as with other dystonic reactions; transient dizziness during or shortly after intravenous infusion

Skin and subcutaneous tissue

Eye Disorders

  • Transient blindness (predominantly during IV administration) was reported to resolve within a few minutes up to 48 hr;
  • transient blurred vision

Musculoskeletal and connective tissue

  • joint pain

Dosage for Zofran

Zofran adult dose is 32-mg given as a single dose or divided in three 0.15-mg/kg divided doses infused over 15 minutes.

What Drugs, Substances, or Supplements Interact with Zofran?

Zofran may interact with arsenic trioxide, tacrolimus, tramadol, antibiotics, antidepressants, anti-malaria medications, heart rhythm medicines, medicine to prevent or treat nausea and vomiting, medicines to treat psychiatric disorders, migraine headache medicines, narcotics, or seizure medications. Tell your doctor all medications and supplements you use.

Zofran During Pregnancy and Breastfeeding

Zofran should not be used during pregnancy unless the benefits outweigh the risks. It is not known if Zofran is excreted in breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Zofran Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Skin Cancer Symptoms, Types, Images See Slideshow
Zofran Consumer Information

1 pharmacies near 75143 have coupons for Zofran (Brand Names:Zofran for 50ML of 4MG/5ML)

Heb Pharmacy
Heb Pharmacy

Est. Regular Price


with free coupon

View Coupon

Get emergency medical help if you have signs of an allergic reaction: rash, hives; fever, chills, difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • severe constipation, stomach pain, or bloating;
  • headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;
  • fast or pounding heartbeats;
  • jaundice (yellowing of the skin or eyes);
  • blurred vision or temporary vision loss (lasting from only a few minutes to several hours);
  • high levels of serotonin in the body--agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting.

Common side effects may include:

  • diarrhea or constipation;
  • headache;
  • drowsiness; or
  • tired feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Zofran Professional Information


The following clinically significant adverse reactions are described elsewhere in the labeling:

  • Hypersensitivity Reactions [see WARNINGS AND PRECAUTIONS]
  • QT Prolongation [see WARNINGS AND PRECAUTIONS]
  • Serotonin Syndrome [see WARNINGS AND PRECAUTIONS]
  • Myocardial Ischemia [see WARNINGS AND PRECAUTIONS]
  • Masking of Progressive Ileus and Gastric Distension [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The following adverse reactions have been reported in clinical trials of patients treated with ondansetron, the active ingredient of ZOFRAN. A causal relationship to therapy with ZOFRAN was unclear in many cases.

Prevention Of Chemotherapy-Induced Nausea And Vomiting

The most common adverse reactions reported in greater than or equal to 4% of 300 adults receiving a single 24mg dose of ZOFRAN orally in 2 trials for the prevention of nausea and vomiting associated with highly emetogenic chemotherapy (cisplatin greater than or equal to 50 mg/m2) were: headache (11%) and diarrhea (4%).

The most common adverse reactions reported in 4 trials in adults for the prevention of nausea and vomiting associated with moderately emetogenic chemotherapy (primarily cyclophosphamide-based regimens) are shown in Table 3.

Table 3: Most Common Adverse Reactions in Adultsa for the Prevention of Nausea and Vomiting Associated With Moderately Emetogenic Chemotherapy [Primarily Cyclophosphamide-based Regimens] Adverse Reaction

Adverse Reaction ZOFRAN 8 mg Twice Daily
(n = 242)
(n = 262)
Headache 58 (24%) 34 (13%)
Malaise/Fatigue 32 (13%) 6 (2%)
Constipation 22 (9%) 1 (< 1%)
Diarrhea 15 (6%) 10 (4%)
a Reported in greater than or equal to 5% of patients treated with ZOFRAN and at a rate that exceeded placebo.

Less Common Adverse Reactions

Central Nervous System

Extrapyramidal reactions (less than 1% of patients).


Aspartate transaminase (AST) and/or alanine transaminase (ALT) values exceeded twice the upper limit of normal in approximately 1% to 2% of 723 patients receiving ZOFRAN and cyclophosphamide-based chemotherapy in US clinical trials. The increases were transient and did not appear to be related to dose or duration of therapy. On repeat exposure, similar transient elevations in transaminase values occurred in some courses, but symptomatic hepatic disease did not occur. The role of cancer chemotherapy in these biochemical changes is unclear.

Liver failure and death has been reported in cancer patients receiving concurrent medications, including potentially hepatotoxic cytotoxic chemotherapy and antibiotics. The etiology of the liver failure is unclear.


Rash (approximately 1% of patients).

Other (less than 2%)

Anaphylaxis, bronchospasm, tachycardia, angina, hypokalemia, electrocardiographic alterations, vascular occlusive events, and grand mal seizures. Except for bronchospasm and anaphylaxis, the relationship to ZOFRAN is unclear.

Prevention Of Radiation-Induced Nausea And Vomiting

The most common adverse reactions (greater than or equal to 2%) reported in patients receiving ZOFRAN and concurrent radiotherapy were similar to those reported in patients receiving ZOFRAN and concurrent chemotherapy and were headache, constipation, and diarrhea.

Prevention Of Postoperative Nausea And/Or Vomiting

The most common adverse reactions reported in adults in trial(s) of prevention of postoperative nausea and vomiting are shown in Table 4. In these trial(s), patients were receiving multiple concomitant perioperative and postoperative medications in both treatment groups.

Table 4: Most Common Adverse Reactions in Adultsa for the Prevention of Postoperative Nausea and Vomiting

Adverse Reaction ZOFRAN 16 mg as a Single Dose
(n = 550)
(n = 531)
Headache 49 (9%) 27 (5%)
Hypoxia 49 (9%) 35 (7%)
Pyrexia 45 (8%) 34 (6%)
Dizziness 36 (7%) 34 (6%)
Gynecological disorder 36 (7%) 33 (6%)
Anxiety/Agitation 33 (6%) 29 (5%)
Urinary retention 28 (5%) 18 (3%)
Pruritus 27 (5%) 20 (4%)
a Reported in greater than or equal to 5% of patients treated with ZOFRAN and at a rate that exceeded placebo.

In a crossover study with 25 subjects, headache was reported in 6 subjects administered ZOFRAN ODT orally disintegrating tablet with water (24%) as compared with 2 subjects administered ZOFRAN ODT orally disintegrating tablet without water (8%).

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of ondansetron. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.


Arrhythmias (including ventricular and supraventricular tachycardia, premature ventricular contractions, and atrial fibrillation), bradycardia, electrocardiographic alterations (including second-degree heart block, QT/QTc interval prolongation, and ST segment depression), palpitations, and syncope. Rarely and predominantly with intravenous ondansetron, transient ECG changes, including QT interval prolongation have been reported.

Myocardial ischemia was reported predominately with intravenous administration [see WARNINGS AND PRECAUTIONS].



Rare cases of hypersensitivity reactions, sometimes severe (e.g., anaphylactic reactions, angioedema, bronchospasm, shortness of breath, hypotension, laryngeal edema, stridor) have also been reported.

Laryngospasm, shock, and cardiopulmonary arrest have occurred during allergic reactions in patients receiving injectable ondansetron.


Liver enzyme abnormalities.

Lower Respiratory



Oculogyric crisis, appearing alone, as well as with other dystonic reactions.


Urticaria, Stevens-Johnson syndrome, and toxic epidermal necrolysis.

Eye Disorders

Cases of transient blindness, predominantly during intravenous administration, have been reported. These cases of transient blindness were reported to resolve within a few minutes up to 48 hours.


Serotonergic Drugs

Serotonin syndrome (including altered mental status, autonomic instability, and neuromuscular symptoms) has been described following the concomitant use of 5-HT3 receptor antagonists and other serotonergic drugs, including SSRIs and SNRIs. Monitor for the emergence of serotonin syndrome. If symptoms occur, discontinue ZOFRAN and initiate supportive treatment [see WARNINGS AND PRECAUTIONS].

Drugs Affecting Cytochrome P-450 Enzymes

Ondansetron does not itself appear to induce or inhibit the cytochrome P-450 drug-metabolizing enzyme system of the liver [see CLINICAL PHARMACOLOGY]. Because ondansetron is metabolized by hepatic cytochrome P450 drug-metabolizing enzymes (CYP3A4, CYP2D6, CYP1A2), inducers or inhibitors of these enzymes may change the clearance and, hence, the half-life of ondansetron. In patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin), the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased. However, on the basis of available data, no dosage adjustment for ZOFRAN is recommended for patients on these drugs [see CLINICAL PHARMACOLOGY].


Although no pharmacokinetic drug interaction between ondansetron and tramadol has been observed, data from 2 small trials indicate that when used together, ZOFRAN may increase patient-controlled administration of tramadol. Monitor patients to ensure adequate pain control when ondansetron is administered with tramadol.


Carmustine, etoposide, and cisplatin do not affect the pharmacokinetics of ondansetron.

In a crossover trial in 76 pediatric patients, intravenous ondansetron did not increase systemic concentrations of high-dose methotrexate.

Alfentanil And Atracurium

ZOFRAN does not alter the respiratory depressant effects produced by alfentanil or the degree of neuromuscular blockade produced by atracurium. Interactions with general or local anesthetics have not been studied.

Drug Abuse And Dependence

Animal studies have shown that ondansetron is not discriminated as a benzodiazepine nor does it substitute for benzodiazepines in direct addiction studies.

Read the entire FDA prescribing information for Zofran (Ondansetron Hydrochloride Tablets and Solution)

© Zofran Patient Information is supplied by Cerner Multum, Inc. and Zofran Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

Health Solutions From Our Sponsors