Ondansetron (Injection)

Ondansetron is a medication that is used to treat the symptoms of nausea and vomiting for patients who are undergoing treatment for cancer, such as radiation therapy or chemotherapy, including the treatment of high-dose cisplatin.


This medication is also used to treat the symptoms of nausea and vomiting for those undergoing surgical procedures, as well as preventing shivering in those undergoing anesthesia. In some cases, a physician will prescribe this medication to prevent morning sickness in women who are pregnant.

This medication blocks serotonin, a natural substance found in the brain that contributes to vomiting and nausea symptoms. This medication is used for both adults and children under close supervision by medical personnel. This medication is only available by a physician's prescription. This drug was approved by the FDA in 1992 under the brand name of Zofran.

Conditions Treated

Type Of Medicine

  • Antiemetic
  • Competitive serotonin type 3 receptor antagonist

Side Effects

Many people taking this medication do not develop side effects from its use; however, there are a range of potential adverse reactions that can occur. If you have been prescribed this medication, your physician has determined that the benefits you may receive outweigh the risks of the potential side effects that you may experience.

Side effects can range from mild to severe. For those experiencing mild side effects, regular contact with your physician may be the only step you may require. If you are experiencing more severe side effects, never leave them unreported or untreated.

Patients should be aware of their condition, and if they experience any of the symptoms listed below, they are to contact their physician or health providers. In cases of severe symptoms, seek medical help immediately at your local hospital or by contacting emergency services on 911.

Potential side effects may include any of the following, as well as some side effects that have not been listed.

Common side effects:

Less common side effects:

  • Burning, prickling or tingling sensations
  • Drowsiness or tiredness
  • Feelings of being cold
  • Itching sensations
  • Cramps, abdominal, or stomach pain
  • Dryness of the mouth

Rare or infrequent side effects:

  • General weakness or weakness of legs and arms
  • Inability to move eyes
  • Eyelid spasms or increased blinking
  • No breathing
  • No pulse or blood pressure
  • Noisy breathing
  • Irregular or slow breathing
  • Pain in the jaw, back or neck
  • Sticking out of the tongue
  • Sweating
  • Welts or hives
  • Fixed position of the eyes
  • Confusion
  • Clammy, cold skin
  • Wheezing
  • Trouble with speaking, swallowing, or breathing
  • Unconsciousness
  • Uncontrolled twisting movements of arms, legs, neck, or trunk of body
  • Unusual facial expressions
  • Stopping of the heart
  • Blurring of vision
  • Rapid, weak pulse
  • Discomfort or chest pain
  • Burning, pain, or redness at injection site
  • Shortness of breath
  • Troubled breathing
  • Tightness in the chest
  • Hives, redness, itching or skin rash
  • Slow, pounding, or fast or Irregular pulse or heartbeat
  • Hive-like swelling of the sex organs, hands, legs, feet, lips, tongue, throat, or eyelids (large size)

If any of the more severe side effects occur, the patient should seek medical help without delay. Use of this medication should always be overseen by a physician and appropriate health professionals. Always use as directed by your physician and always follow the exact directions or instructions provided by your health professionals.

This medicine can cause serious side effects in older adults, such as QT prolongation. Children may develop heart rhythm problems as a result of taking this medication. If you or your child develop these symptoms, it is imperative that you talk to your doctor right away, as the most serious of these side effects can be life-threatening.

Side effects are usually milder, commonly, and the more severe types are usually rare. It is important for the patient to be fully aware and know what all of the potential side effects of this medication are, so that they know what to look for and can be prepared in the event that they do occur. A full briefing and consultation with their physician, as well as listing them for personal reference, is essential, especially the more serious side effects.

The list above is not a complete list of known or potential side effects, and some side effects may occur that are not listed. If you should experience any side effects from the use of this medication, you should report them to the FDA by phone at 1-800-FDA-1088 or by visiting the website at www.fda.gov/medwatch.


A physician may need to adjust the dosage of this medication at varying intervals along the course of its use. This medication in this form, injection, can only be administered by medical personnel. The dosages for adults and children are as follows:


Chemotherapy treatment

See labels for full instructions. Vials must be diluted before use. For patients over 18 years of age, infuse patient with a dose measuring 0.15mg/kg (a maximum of 0.16mg/kg) in IV form every four hours for a total of three doses for 30 minutes prior to chemotherapy. For patients with severe hepatic dysfunction, a maximum of 8mg a day can be used.

Perform infusions in not less than 30 seconds, preferably over durations lasting two to five minutes. A 4mg IV as a single dose is permitted before anesthesia, or immediately after post-op if vomiting or nausea develop. The use of 4mg, undiluted, in single dose form may be used.


Chemotherapy treatment

See labels for full instructions. Vials must be diluted before use. For children who are less than six months of age, infuse medication by IV over a period of 15 minutes. For children 6 to 18 months of age, infuse a dose of 0.15mg/kg over a period of four hours a total of three times, beginning 30 minutes prior to chemotherapy. For post-op infusion, do not dilute. Infuse in a time frame not less than 30 seconds, preferably over periods of two to five minutes.

For infants less than one month of age, see full label directions; for infants one month to 12 months of age, use 0.1mg/kg. Administer this medication as a single dose immediately prior to anesthesia induction, or after post-op vomiting or nausea develop.

Skipping doses is not likely to occur, as the administration of this medication occurs in a hospital setting and is performed by medical personnel. In the case of accidental overdose, check the patient and monitor for symptoms of a collapsed body or lack of breathing, and immediately alert the physician and other medical personnel. Seek immediate treatment if there are complications due to the dosage or other adverse reactions.

Symptoms of overdose include the following:

  • Constipation
  • Irregular heartbeat
  • Short term vision loss
  • Fainting, lightheadedness or dizziness


These drugs interact negatively with this medication and can cause extremely harmful effects. In the case of extreme symptoms or acute problems, always contact your physician or call 911 immediately to treat symptoms. Do not wait for them to go away on their own; always seek medical help. Make your physician fully aware of all medications you take, and never take any of the following drugs when using this medication:

  • Inotuzumab Ozogamacin
  • Bepridil
  • Anagrelide
  • Pimozide
  • Amifampridine
  • Dronedarone
  • Halofantrine
  • Artemether Lumefantrine
  • Sparfloxacin
  • Disomyramide
  • Levomethdryl
  • Droperidol
  • Cisapride
  • Sertindole
  • Ziprasidone

These drugs cause moderate negative reactions when using this medication and should be avoided. Patients should consult with their physician when using this or any medication and physician should monitor medication use to reduce any potential interactions that may occur.

  • Efavirenz
  • Risperidone
  • Hydroxychloroquine
  • Dolasetron
  • Hydroxyzine
  • Propafenone
  • Pimavanserin
  • Formoterol
  • Lenvatinib
  • Gemifloxacin
  • Delamanid
  • Norfloxacin
  • Ceritinib
  • Nalidixic Acid
  • Trazodone >100 milligams
  • Amiodarone
  • Bedaquiline
  • Ivabradine
  • Pasireotide
  • Ranolazine
  • Sorafenib
  • Posaconazole
  • Quetiapine
  • Dasatinib
  • Crizotinib
  • Gadoxetate
  • Vemuravenib
  • Paliperidone
  • Ezogabine
  • Lapatinib
  • Rilpivirine
  • Nilotinib
  • Gadofosveset
  • Zuclopenthixol
  • Eribulin
  • Tetrabenazine
  • Romidepsin
  • Quinine
  • Saquinavir
  • Torimifene
  • Vinflunine
  • Asenapine
  • Iloperidone
  • Lopinavir
  • Tramadol
  • Telavancin
  • Pazopanib


Consult with your physician before taking this medication. This medication may cause dizziness or lightheadedness, so before operating heavy machinery, one should take precautions and be aware of whether they are in a safe condition to drive or work. If you experience these symptoms, avoid the operation of heavy machinery and find a safe alternative, even if it is inconvenient to do so, as putting yours or others' lives at risk is unacceptable.

If a child is less than four months of age, they must be monitored closely. This medication is not a substitute for intestinal peristalsis or nasogastric suction. This medication may mask gastric distention and progressive ileus. Those taking this medication must be monitored for decreased bowel activity, GI obstruction risks and hepatic dysfunction.

Those who are pregnant, planning to become pregnant or nursing mothers should consult with a physician and make them aware of their condition before using this medication. It is not known whether using this medication causes and undesirable effects in infants when used by mothers who breastfeed.

Those using apomorphine should take precautions when using this medication, as profound hypertension and loss of consciousness may occur. Those using concomitant serotonergic drugs, such as MAOIs, SNRIs or SSRIs, run the risk of developing serotonin syndrome. Your physician should be made aware of the use of any of these drugs prior to use of this medication.

Whether you have a pre-existing allergy to this medication should be determined before you use it. Do not use this medication if you are allergic to it, as life-threatening reactions can occur. If you are allergic to any other anti-nausea serotonin blockers, make sure your physician is fully aware of this before you use or continue to use this medication.

Low levels of magnesium or potassium in your blood while using this medication may lead to an increased risk of QT prolongation. Make sure to alert your physician if you have certain medical conditions, such as slow heartbeat or a history of heart failure, or if there is a family history of cardiac arrest or QT prolongation in the EKG.

Make sure your physician is fully aware of your medical history and fill them in if you have a history of liver disease, stomach or intestinal problems, or irregular heartbeat. If you have had a recent abdominal surgery or swelling, or ileus, tell your doctor.

An extremely severe allergic reaction known as anaphylaxis can occur in some patients. This condition is life-threatening and should be reported immediately to 911 or hospital personnel. Symptoms of anaphylaxis include hoarseness, trouble breathing, rash, itching, and swelling of your hands, mouth or face. Do not hesitate to report these symptoms and seek medical intervention without delay, as this condition can be fatal if left untreated.


Ondansetron injection has a shelf life over three years when stored at temperatures below 30 degrees. This medication should be stored in safe, secure areas. Storage should be conducted out of exposure to direct light for extended periods of time.


This medication is highly effective in treating the symptoms of vomiting and nausea in adults and children undergoing treatment for cancer, such as chemotherapy and radiation therapy. This medication can also be used to effectively prevent symptoms of shivering in those undergoing anesthesia, and for pregnant women who suffer from symptoms of morning sickness. The risk of severe side effects is generally quite low and most people do not develop adverse reactions when taking this medication.

This medication is well tolerated and does not present any health risks beyond the potential for side effects. When side effects do occur, patients can often be seen by physicians and medical personnel and adequately treated before there are any serious health risks. In all cases, physicians and other medical personnel should oversee the use of this medication and should be made aware of all drugs used by you or the patient.

In some rare cases, there are conditions and side effects that may be serious, even though this medication is safe for most people and approved for use by the FDA. A physician is the only one who can prescribe this medicine, and since this medication in taken through the route of injection, only medical personnel are authorized to administer it.

There are a wide number of medications that create serious interactions with this medication, and care should be taken to avoid concurrent use. Many over the counter medications also present interaction risks, and the patient should always consult with their physician at length before using this medication or going home from the hospital and using any medication or herbal supplements or vitamins.

Physicians treating patients with this medication need to be fully aware of the medical condition of the patient, the medical history of the patient and the medical history of the family of the patient. Those who have had certain medical conditions should make their physicians aware of them before they are treated with this medication.