Zofran Side Effects

Generic Name: ondansetron

Note: This page contains side effects data for the generic drug ondansetron. It is possible that some of the dosage forms included below may not apply to the brand name Zofran.

It is possible that some side effects of Zofran may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

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

Other dosage forms:

As well as its needed effects, ondansetron (the active ingredient contained in Zofran) may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking ondansetron, check with your doctor immediately:

More common
  • Confusion
  • dizziness
  • fast heartbeat
  • fever
  • headache
  • shortness of breath
  • weakness
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 ondansetron side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned 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


In general, headache is the most common adverse effect reported. Transient dizziness during or shortly after the IV infusion has also been reported during postmarketing experience.


A causal relationship between intestinal obstruction and ondansetron (the active ingredient contained in Zofran) has not been established.

Gastrointestinal side effects including constipation (up to 15%) and diarrhea have been reported. Several cases of intestinal obstruction have been reported. Nausea and vomiting have been reported with the use of intravenous ondansetron during postmarketing experience.


Hepatic side effects have included mild elevations of liver function tests. The clinical significance of these elevations is unknown. Cases of jaundice have also been reported rarely. One case of pancreatitis was reported in a patient using ondansetron (the active ingredient contained in Zofran) long-term. Liver failure and death have been reported in patients with cancer receiving concurrent medications, including potentially hepatotoxic cytotoxic chemotherapy and antibiotics, and intravenous ondansetron during postmarketing experience.


Cardiovascular side effects have rarely included angina and acute myocardial ischemia. Arrhythmias (including ventricular and supraventricular tachycardia, premature ventricular contractions, and atrial fibrillation), bradycardia, electrocardiographic alterations (including second-degree heart block, QT interval prolongation, and ST segment depression), palpitations, syncope, Torsade de points, ventricular fibrillation, and chest discomfort have been reported with the use of intravenous ondansetron (the active ingredient contained in Zofran) during postmarketing experience.

One study has suggested that prolongation of the QTc interval may occur in many patients treated with cisplatin and ondansetron simultaneously. In that study QTc prolongation occurred in 6 of 8 patients who received a combination of ondansetron and cisplatin. Five of the patients had prolongations of the QTc interval which were greater than 5%. However, no episodes of arrhythmia, hypotension, ischemia, congestive heart failure or other cardiovascular events were observed.

Similarly, results of a review of the cardiovascular effects of the drug class 5-hydroxytryptamine 3 receptor antagonists in the literature reported that electrocardiographic (ECG) changes were so small to be considered clinically insignificant. ECG changes were most noticeable between 1 to 2 hours after a dose of ondansetron and returned to baseline within 24 hours. To date, no serious cardiac side effects (including torsades de pointes) triggered by ECG interval changes have been connected with the use of 5-HT 3 receptor antagonists.


Hypersensitivity side effects have rarely included rashes. Twenty-four reports of anaphylactoid-anaphylactic reactions following intravenous administration of ondansetron (the active ingredient contained in Zofran) have been reported in postmarketing experience. One report suggests hypersensitivity reactions with 5-HT 3-antagonists may be a class effect and cross-reactive.


Psychiatric side effects have rarely included depression.

A brief episode of ondansetron-induced depression has been reported in one woman whose depression was controlled with fluoxetine. A 41-year-old woman became suicidally depressed seven days after receiving ondansetron prior to arthroscopy. The depression was controlled with fluvoxamine, alprazolam, and flunitrazepam.


Dermatologic side effects have included pruritus (5%) and rash (1%). A suspected fixed drug eruption with the lesions appearing macular and pruritic has also been reported. Rechallenge lead to regression of the lesions. Urticaria, hyperhidrosis, pruritus, and purpura have been reported with the use of intravenous ondansetron (the active ingredient contained in Zofran) during postmarketing experience.
Postmarketing reports: Stevens-Johnson syndrome and toxic epidermal necrolysis

Nervous system

Nervous system side effects have included dizziness (18%) and extrapyramidal reactions, including twitching tremors, opisthotonos, severe jerking movements, and numbness. In many of these cases, diphenhydramine (25 mg to 50 mg) was effective for treatment or prevention. Chills, lethargy, and oculogyric crisis, appearing alone, as well as with other dystonic reactions have also been reported with the use of intravenous ondansetron (the active ingredient contained in Zofran) during postmarketing experience.

Rechallenge with ondansetron lead to a reoccurrence of the opisthotonos in one patient. Patients with a history of drug-induced dystonic reactions may have a similar response after ondansetron therapy.


Ocular side effects have rarely included blurred vision, in some cases associated with abnormalities of accommodation. Rare cases of transient blindness have also been reported, predominantly during intravenous administration.

Transient blindness (a duration of 2 to 3 minutes) generally resolved within 20 minutes up to 48 hours.


Respiratory side effects have included hiccups with the use of intravenous ondansetron (the active ingredient contained in Zofran) during postmarketing experience.


Local side effects have included pain, redness, and burning at injection site with the use of intravenous ondansetron (the active ingredient contained in Zofran) during postmarketing experience.


Musculoskeletal side effects have included arthralgia reported with the use of intravenous ondansetron (the active ingredient contained in Zofran) during postmarketing experience.

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